MOLLUSCA. 



21 



over each side of the shell, and acting as oars, the animal fre- 

 quently sails on the surface of the water, like a little vessel. 



Division III. Cephalopoda Pu'.ythalama. 

 FAMILT I. AMMONACEA. 



Septa sinuous, lobed and rut at the margin, meeting together 

 , upon the inner wall of the shell, and articulated by jagged 

 sutures. 



Shell multilocular, partly or entirely internal, and inserted 

 in the posterior part of the body. 



All the species of this division are fossil, for the generic char, 

 ucters see Organic Remains. 



FAMILY II. NAUTILACBA. 



Shell discifortn, with a central spine, and short cells, which do 

 not extend from the centre of the circumference. 



Nautilut Pompiliiu. PI. 17. f. 3, and pi. 60. f. 63. The ani. 

 inal, according to Rumphius, is partly contained within the last 

 cell, has the sac, eyes, parrot-beak, and funnel of the other 

 Cephalopoda; but the mouth, in place of having their large 

 feet and arms, is surrounded by several circles of numerous 

 small tentacula, which are destitute of cups ; a ligament arising 

 from the back traverses the whole siphon and fastens it there". 

 The other genera are fossil. See Organic Remains. 



FAMILY III. RADIOLACEA. 

 All the genera are fossil. See Organic Remains. 

 FAMILY IV. SPBERULACBA. 



Fossil, except one species found near Corsica, which is so 

 minute that the animal has not been ascertained. See Organic 

 Remains, plate 66. 



FAMILY V. CRISTACEA. 

 All the species are fossil. See Organic Remains, pi. 66. 



FAMILY VI. LITUOLACEA. 



Shell partially spiral ; the last volution continued in a 

 straight line. 



Spirttla Peronii. PI. 17. f. 4. Animal a cephalopode, pi. CO. 

 f. 2. The body or that part which inhabits the shell, a. 



FAMILY VII. ORTHOCERATA. 



Animals of the genera unknown. See Conchology, Vol. II. 

 p. 376. 



ORDER III. TRACHELIPODA. 



Body usually spirally convoluted, and separated from the 

 foot, which is free, flat, and attached to the neck at its base for 

 the purpose of locomotion ; the body always enveloped by a 

 spiral shell. 



SECTION I. ZOOPHAGOUS TRACHELIPODA. 

 FAMILY I. INTOLUTA. 



Shell destitute of a canal, but with the base of its aperture 

 notched or effuse, and its volutions broad, compressed, and 

 rolled up in such a manner, that the last nearly covers all the 

 others. 



('onus generalii. PI. 60. f. 3. The thinness of the animal is 

 proportioned to the narrowness of the aperture through which it 

 passes ; its tentacula and proboscis are highly protractile ; the 

 eyes are situated on the outer side of the former, and near the 

 point ; the operculum placed obliquely on the hind part of the 

 foot, is too narrow and short to close the whole of the aper- 

 ture. It has a narrow mantle and tube situated above the 

 head, by which the water gains admittance to the respiratory 

 organ. 



Cypr&a Europea. PI. 60. f. 8. The proboscis is deep ver- 

 milion coloured ; the tentacula yellowish red, spotted with 

 yellow ; the upper part of the foot streaked longitudinally with 

 yellow and brown ; and the mantle greenish brown, edged 

 with brownish red. 



Buccinum undatum. PI. 60. f. 19, 20. The extracted ani- 

 mal ; a a, the foot ; />, the head ; r, a kind of platform raised 

 above the thoracic cavity, on which the point of the boring 

 trunk rests. This organ is represented at f. 31, 32, and 33, 

 d, d; f. 34 is a magnified view of the stomach and alimentary 

 tubes; d, the cavity of the thorax; e, the mantle;/, the rectum; 

 g, the stomach; h, the heart, thrown below, and to the right 

 side of its natural situation, to allow the opening of the tube 

 to be seen ; , the respiratory trunk ; k, the organs of the 

 muscles of the boring trur.k; I, the course of the tube by which 

 the foot is supplied with water ; m, its termination. 



FAMILY II. COLCMELLARIA. 



No canal at the base of the aperture, but a subdorsal notch 

 more or less apparent, and fold upon the columella. 



Valuta Scapha. PI. 17. f. 14. The animal has a large thick 

 and fleshy foot, and the head is provided with a vail from the 

 sides of which issue the tentacula ; the proboscis is rather long, 

 and there is an appendage on each hide of the base of the 



siphon. When the probosclt is extended, it can bend in all 

 directions, by means of the retractor muscles, acting with 

 opposing forces. This interesting mechanism is illustrated by 

 fig. 32, pi. 60. the proboscis is represented retracted about a 

 half; the external cylinder, a, is seen enveloping a portion of 

 the inner one, b, the point of which c is the termination of the 

 proboscis ; the muscles which draw it within the body, dd, arc 

 in a state of contraction, and at e is represented the great an- 

 nular muscle, which pushes forward the inner cylinder, and 

 consequently lengthens the organ. 



FAMILY III. PURPURIFERA. 



Shell with a short canal ascending posteriorly, or with an 

 oblique notch at the base of its aperture, directed backwards. 

 They are all operculate. 



Purpura lapillut. With two slender retractile tentacula, 

 on which are placed the eyes. A vascular reservoir near the 

 stomach yields a colour similar to the famous Tyrian purple. 



FAMILY IV. ALATA. 



Shell with a greater or less canal at the base of the aperture, 

 of which the right lip changes its form as the animal advances 

 in age, and has a sinus at the lower part. 



Strombus Succinctut. PI. 17. f. 28. 



FAMILY V. CANALIFERA. 



Shell with a canal more or less long at the base of the aper- 

 ture, and of which the right margin does not change its form 

 as the animal advances in age. 



Murex acanthopterut. PI. 17. f. 32. The animals of each 

 sub-genus are furnished with a proboscis ; long approximate 

 tentacula, on the external side of which are the eyes ; and a 

 horny operculum ; they are destitute of the veil on the head ; 

 and the want of the siphon excepted, resemble the animals 

 of the Buccina. 



SECTION II. PHYTIPHAGA. 



Destitute of projecting siphon, and respiring generally by an 

 orifice ; furnished with jaws, and feeding on vegetables, shell 

 with the aperture entire, and without any notch or canal. 

 Many of the species live upon land, and respire air, while 

 others inhabit fresh water, either stagnant or running. Many 

 are marine. Some families are furnished with an operculum 

 attached to the foot of the animal. 



FAMILY I. TURBINACEA. 



Shell turreted or conoid, having an oblong or rounded aper 

 ture, not widened, and the margin disunited. 



Turbo tmaragdut. PI. 17. f. 45. The animal has two long 

 tentacula ; and the eyes placed on peduncles at their external 

 base; the sides of the foot are provided with membranous 

 wings, sometimes simple, at others fringed, and occasionally 

 furnished with one or two filaments. 



Turbo littoreus. PI. 60. f. 13. Animal striped with black ; 

 provided with two tentacula, which are setaceous, not quite 

 round, with black annulations ; eyes prominent, situate at the 

 base of the tentacula. 



FAMILY II. SCALARIDES. 



Shell devoid of plicae or folds on the columella; the margins 

 of the aperture are united in circular forms. 



Scalaria coronata. PI. 17. f. 51. The tentacular organs of 

 generation are long and slender, terminating in a setaceous 

 filament ; the eyes are situate at the base of these filaments. 



FAMILY III. PLICACEA. 



Shell with the aperture not widened, and folds on the colu- 

 mella. 



Tornatellaflammid. PI. 17. f. 54. 



FAMILY IV. MACHOSTOMA. 



Shell auriform, with the aperture very wide, and the mar- 

 gins disunited; destitute of columella and operculum. 



Haliotii tuberculata. PI. 17. f. 55, and pi. 60. f. 12. The 

 animal is one of the most highly ornamented ol its order. A 

 double membrane, cut into bands and provided with a double 

 range of filaments, extends, at least in the more commonly 

 known species, round (lie foot and on the mouth ; outside its 

 long tentacula are cylindrical pedicles which support the eyes. 

 The mantle is deeply cleft on the right side, aud the water 

 which passes through the shell, penetrates this canal into the 

 branchial cavity ; along its edges three or four filaments are 

 observable, which the animal has tfce power of protruding 

 through these holes ; the mouth is in the form of a short pro- 

 boscis. 



Sigaretus Haliotoideus. PI. 60. f. 42. Shell concealed in the 

 mantle ; in, the membranous shield under which the shell is 

 concealed ; n, a sinus through which an nrm is sometimes pro- 

 truded ; o, the tentacula, at the base of which the eyes are 

 placed. 



FAMILY V. IANTHENIA. 

 Shell gibbous, conoidal, thin, transparent ; aperture triangu- 



