JOO 



MUSEUM OF ANIMATED NATURE. 



[TeCTIBRA NCUI ATA. 



hibiU the animal teen from above ; b, leen from 

 below. 



2G47.— TnK RosEATK Milide 



(MtliOe roMo). In this >ea-slug, which approxi- 

 mate* to Tethyt, the body i« oomewhat limacilurm, 

 gelatinou*. and trantparent ; tlie head is I'urniithed 

 with a Ciinnel-like vfiI, beset interiorly with cirrhi, 

 directed outwardly, and leading to a mouth termi- 

 nating a small proboscis. Two long slender ten- 

 tacles rise from the base of the veil, each terminated 

 by a small capsule, from the centre of which rises a 

 snort retractile filament. Foot as long as the ani- 

 mal, but narrow, and in the form of a furrow. 

 Branchiie constisting of two series of club-like pro- 

 cesses, which are rounded at their summit, pedicu- 

 lated at their base, and covered with small tubercles. 

 This animal was observed by M. Rang living upon 

 various floating; plants in the seas near the Cape of 

 Good Hope. It swims well by agitating the pos- 

 terior paits of the body from siile to side. A slight 

 touch IS sufficient to cause disengagement of the 

 branchiie, as in the Glaucus. Kel'erring to the 

 figure; b is the veil around the mouth; e, the 

 tentacles; </, the branchial club-shaped processes; 

 A and I, arious orilices ; I, the foot ; «, the caudal 

 extremity. 



2647.* — TuE Pelagic Sctujka 



(Scy/laa pehffica). In this genus the head is not 

 very distinct, and of a horseshoe shape ; and there 

 arc two large tentacles somewhat club-shaped, but 

 flattened, and split anteriorly, and open at the 

 summit, for giving passage to a small retractile 

 pointed body. The mouth terminates a minute 

 proboscis, and is furnished with an apparatus for 

 mastication. The foot is long, narrow, and furrow- [ 

 like ; the branchiie are in the form of small tufted 

 pencils scattered over the inner surface of several i 

 appendages of skin, rising from the middle ridge of 

 the back. The Scyllapa is extensively spread through 

 the w armer seas, and is to be found among the fronds 

 of the Fucus natans, to which its channeled foot, 

 acting as an efficient grasper, enables it to cling ! 

 with ease. I 



2G48. — Hombebg's Tritonia [ 



(Tiilonia Hombergiiy This genus approaches i 

 Scylliea. The head is surrounded by two retractile I 

 , tentacles; the frontal veil is but little developed, ! 

 and the branchisD are in the form of branching tufts I 

 ranged down each side of the back : the mouth is 1 

 furnished with two lateral horny jaws like shears, ] 

 trenchant and denticulated at the edges. Foot long I 

 and l^urrowed. These animals attach them.selve8 to 

 floating sea-weed. Several species exist along the i 

 coasts of France, among which is the Tritonia Hom- | 

 bergii ; it is of a copper colour. 



2649. — The Oceixatkd Pi.acodkanchus 

 {PlacnbiancUus oceUatus). The Placobranchus is 

 oblong in figure, with a mantle on each side, in the 

 form of two membranous semicircular fins, extending 

 from the neck to the end of the body, capable of 

 being elevated and folded on each other over the 

 back so as to form a sort of tube or canal through 

 which the water circulates, laving the branchiK. 

 The branchiK, resembling delicate close-set longi- 

 tudinal Limellae, cover the back and lobes. Head 

 depressed, with two small approximated eyes and two 

 pairs of short conical tentacles. The sea-slug on 

 which M. Rang founded this genus was discovered 

 \yf Van Hasselt on the coast of Java. Referring to 

 Fig. 2649; c shows the upper tentacles; d, the 

 lower ; b, the lobes of the mantle ; /, the branchite 

 The sea-slugs are oviparous. Mr. Darwin thus 

 writes respecting the Doris:— "While at the Falk- 

 lands during the autumn of the southern hemisphere 

 most of the lower marine animals were breeding' 

 1 was surprised while counting the eggs of a lar|e 

 white Dons (this sea-slug was three and a half inches 

 Jong) to find how extraordinarily numerous they 

 were. From two to five eggs (each three-thou- 

 sandths of an inch in diameter) were contained in a 

 spherical little case; these were arranged two deep 

 in transverse rows forming a ribbon. The ribbon 

 adhered by its edge to the rock in an oval spire • 

 one which I found measured nearly twenty inches 

 in length, and half in breadth. By counting how 

 many balls were cont»ined in a length of an inch 

 in the row, and how many rows in an equal length 

 of the nbbon, on the most moderate computation 

 there were six hundred thousand eggs. Yet this 

 Dons was not very common : although I was often 

 searching under the stones, I only saw seven indi- 

 viduals. 



ORDER INFEROBRANCHIATA. 



The Inferobranchiata have very nearly the same ' 

 organization as the animals of the previous order- 

 but their branchiffi, instead of being sealed on the 

 baek, are in the form of two long series of foliations 



down each side of the body underneath the extended 

 edge of the mantle. 



2650. — The Pustulab Phtluoia 



{Phyllidla jnatulosd). This singular sea-slug, with 

 various allied species, is found in the Indian seas. 

 The mouth is tubular, and there arc four small re- ; 

 tractile tentacles. i 



2GS1. — BauGMAMs's Dipiitllipia i 



{Dinlii/Uidia Brvt/matuii, Ciiv.), I.inguella Elfortii, i 

 De HIainville. The genus Dipliyllidia of Cuvier, or ! 

 Linguella of De Blainville, differs little from the 

 preceding, excepting that the mantle is more pointed 

 Lwhind. The exact locality of the present species 

 is not ascertained, but an allied sea-slug has been i 

 found by M. Otto off the coast of Naples. 



The above are the only two forms of the Infero- 

 branchiata given by Cuvier in his ' Rdgne Animal,' 

 and of these little is known. It cannot, however, 

 be doubted but that other genera will be added from 

 time to time ; yet after all there is little in the his- 

 tory of these animals to interest the general reader, 

 though their anatomy maybe important to the phy- 

 siologist. 



ORDER TECTIBRANCHIATA. 



In this order the branchiae, in the form of leaflets 

 more or less divided, aie attached along the right 

 side, or seated on the back. The mantle covers 

 them more or less, and contains almost always in 

 its substance a small shell. In some the shell is 

 more fully developed, as in Ancylus, Bulla, &c. 



2652.— The Depilatobt Apltsia 



{Aplysia devi'tans). In this genus the body pre- 

 sents a single solt fleshy mass; there are four dis- 

 tinct flattened tentacular appendages : the mouth is 

 in the form of a vertical tissure, with two lateral 

 and somewhat horny labial plates, and a cordiform 

 tongue beset with dentacles ; eyes sessile between the 

 two pair of tentacles ; branchiae covered by a sort 

 of operculum ; shell wanting or incomplete : from 

 the borders of the mantle is poured out abundantly 

 a deep purple liquor, with which the animal colours 

 the water around to a considerable distance, when 

 it perceives any danger. Many species are known ; 

 they feed on seaweed. The Aplysia depilans, with 

 two or three besides, is found in the European seas; 

 it has been long known in the records of supersti- 

 tion as the Sca-H.ire, and was invested with noxious 

 properties ; it is indeed extremely fetid, and exudes 

 an acrid humour, which was supposed to occasion 

 the loss of the hair. This sea-slug is often captured 

 by fishermen in their nets, when it suddenly stains 

 the water around it, to their astonishment. The di- 

 gestive apparatus consists of an enormous crop, 

 leading to a muscular gizzard, furnished with pyra- 

 midal cartilaginous teeth ; and a third stomach be- 

 set with pointed hooks, so as to form a carding ma- 

 chine for tearing the food in pieces, besides a fourth 

 sacculus. 



The Aplysia depilans is blackish, more or less 

 blotched with grey or brown, tinged with purple. 

 It adheres to rocks. 



2653.— The Dolaiieixa 



(Dolabella Hvniphii). The inside of the shell is 

 represented at o, the outside at b. 



The genus Dolabella, according to Cuvier, differs 

 from Aplysia principally in the position of the 

 branchiae, which are placed at the posterior part of 

 the body. The dorsal plate is a hard calcareous 

 shell. The Dolabella Kuniphii is a native of the 

 Indian seas ; other species are found in the Medi- 

 terranean. 



2654. — The Bi:rsateixa 

 (Bursatella Lencliii), This large and singular spe- 

 cies, which appears to be closely allied to Aplysia, 

 is a native of the Indian seas. The body is subglo- 

 bular, with an oval disc or foot below, and with a 

 symmetrical oval opening above, formed by the na- 

 tatory appendages of the mantle, and communicat- 

 ing with a cavity in which is a large free foliaceous 

 gill. There are four branched tentacles, and two 

 labial appendages. 



2655. — Cuvikr's Notarchus 

 (Notnrchus Cuvieti). The Notarchus is a scaslug 

 allied to the former, having the lateral crests united 

 and covering the back, excepting a longitudinal 

 fissure which conducts to the branchiae. The foot 

 is elongated. Shell wanting. 



2666. — ^TnK Porous Bebthklxa 

 (Berthella porosn). This marine slug, which was 

 first described by M. de Blainville (from a specimen 

 sent to him by Dr. I.each), as the type of a distinct 

 genus, is noticed bv Donovan as a species of Bulla 

 (Bulla plumula). The body is oval, convex above, 

 with a delicate shell in the mantle ; the foot is oval ; 



two tentacles are seated on the head, at the root of 

 which are placet the eyes. There is a single pecti- 

 niform branchia on the right side, attached, anteri- 

 orly, but in a great measure free behind. The ani- 

 mal does not appear to be common. Referring to 

 Fig. 2&')C, a represents a side view of this sea-slug • 

 b, a view of the back, to show the internal shell. ' 



2657. — The Freckleo A^ctlus 



{Ancylut irroratui). The ancyli are little fresh- 

 water slugs, covered with a shell much like that of 

 a limpet, but more compressed, and with the apex 

 placed more backward ; like the marine limpets, with 

 , which they have been associated by some naturalists, 

 , they are found adhering to stones and leaves in 

 fresh-water springs and streams, and creep with a 

 slow motion. We have specimens now Ijefore ui 

 of a British species, which we found under stones,' 

 in a clear stream near Reading. 

 I In this molhisk, the head is distinct, the mouth 

 large, the tentacles two and retractile, with the eyes 

 at their base ; the branchia; are in a sort of cavity 

 in the middle of the left side, between the foot and 

 mantle, the animal being, as Rang considers, sinis- 

 trorsal. 



The Ancylusirroratus is found in abundance on the 

 island of St. Vincent, inhabiting the fresh-water 

 streams and ditches. The shell is concentrically 

 plaited, and covered by a dark green epidermis 

 I sprinkled with black: themollusk is pale yellowish, 

 obscurely sprinkled wiih black; the foot spotless 

 and pallid. Length of shell three lines. 

 I Referring to Fig. 2657, a represents the animal 

 creeping, magnified ; ft, the animal reversed ; c and 

 d, the shell ; e, the fieure of the foot, with /, the 

 branchia; in situ ; g, the animal with the shell re- 

 moved. 



2658. — The Radiated Akcti.cs 



{Ancylus radiatus). The Radiated Ancylus is found 

 with the preceding species. The shell is glassy, 

 diaphanous, with slight concentric plaits, and stri- 

 ated radially. The moJlusk is yellowish, sprinkled 

 with black, and with three or four pale marks on 

 the back. 



Referring to Fig. 2658, a represents the animal 

 creeping, magnified; ft, the natural length of the 

 shell; c, the shell magnified. 



2659. — Meckel's Plelbobra>ch^a 



(Plewobranchtra Mecheli). Pleurobranchidium 

 Meckeh, Blainv. This species, the type of the 

 genus I'leurobranchffia, is a slug-like animal found 

 in the Mediterranean. The head is large, with the 

 mouth prolonged in the form of a proboscis; there 

 are two pairs of tentacles, separated considerably 

 from each other. The foot is very large ; the man- 

 tle, almost obliterated, shows itself along the right 

 side only in a narrow expension of skin, below 

 which is a pectinilorm bianchial foliation. There 

 is no trace of a shell. 



2660. — The Pleirobranchcs 



(^Pleurobranchus). In this genus the general form 

 is slug-like, convex above, with a large spreading 

 mantle, often with a thin calcareous shell developed 

 in its substance. The foot is large and outspread- 

 ing; the head distinct, with a membranous veil, and 

 two tubular tentacles. The mouth is at the ex- 

 tremity of a proboscis, and the branchia;, composed 

 of a double row of lamella?, form a plume along the 

 posterior part of the right side. 



Referring to Fig. 2660, ft is the veil ; c, the mouth 

 at the extremity of the proboscis ; e, the tentacles ; 

 g, the branchial lamellns ; h and i, two apertures ; *, 

 the mantle ; /, the loot. 



Many species, some of large size and beautiful 

 tints, are found in the Mediterranean and the open 

 ocean. Ihey have been taken at depths varying 

 from the surlace to thirty fathoms on rocky coasts, 

 stony beds, and masses of sea-weed. Fig. 2C61 re- 

 presents the Pleurobranchus reticulatus seen from 

 above, showing the reticulations of the mantle, and 

 the bianchial lamella; beneath the posterior edge 

 of the mantle on the right side. Fig. 2662 repre- 

 sents, n, the shell of the Pleurobranchus membrana- 

 ceus, external view; ft, the same, infernal view. It 

 reminds us of the shell of Ancylus. 



2663. — The Mediterranean Umheei.la 



{Umbrella Mediterranea). The genus Umbrella is 

 closely allied to Pleuiobranchus. The slug is 

 oblong, much depressed, convex .ibove, very fleshy 

 below; the head is not distinct; the mouth is 

 situated in a deep narrow notch in front of the foot, 

 which has thick edges and is raised all round, and 

 is large and spreading, with a smooth and flat uiider- 

 surface; there are four tentacles ; the branchiae are 

 foliaceous, disposed along the right side ; the 

 mantle supports an external calcareous shell, 

 irregularly circular, slightly convex above, con- 

 centrically striated, with a conical apex, reminding 



