SUB-CLASS CIRR HO POD A. ORDER AC AMPTOSOMATA. SESSILE. 



137 



Type of the genus, P. vidaceus, Lamarck. Inhabits the European seas. 



Illustration : Pdydinum constellatum. 



SIGILLINA. Animal agglomerated, biforous, forming by their union a 

 common gelatinous body, elongate-conical, somewhat pedunculated, with 

 scattered tubercles ; animals not disposed in any particular or distinct 

 system ; tubercles of the surface with two pores ; mouth with six tentacula ; 

 anal orifice with six teeth. 



Type of the genus, S. Australis, Lamarck. Inhabits the coasts of New 

 Holland. 



Illustration : Sigulina Australis. 



DISTOMA. Body common, sessile, half cartilaginous, polymorphous ; 

 composed of many animals generally placed in a circular disposition ; animals 

 placed in one or two ranges, at a coequal distance from their common centre ; 

 the brachial mouth furnished with six regular equal rays, the anal aperture 

 similar; the thorax small, cylindrical, netted with a papillary brachial 

 surface ; abdomen below, longly pedicelled, longer than the thorax ; liver 

 none ; ovary unique, sessile, lateral, occupying the whole of one side of the 

 abdomen. 



Distoma ruhrum is the type. Distama varidosum was first found by 

 Gaertner on the stems of the Ficus Palmatus, on the coast of England. 



Illustration : Distoma ruhrum. 



SYNOICUM. Bodies long and vertical, united in small numbers, and 

 forming a kind of fluted cylinder, excavated at the extremity by a star-shaped 

 orifice, produced by the union of the anal orifices. 



The characters of this genus are, the two mouths of each animal opening 

 at the bottom of a cavity more or less deep, formed by the union of their 

 coverings, which has only one external aperture, commonly furnished with 

 six tentacular papilla. 



Illustration : Synaicum Turgens. 



SUB-CLASS CIERHOPODA. 



THE Cirrhopodous Molluscs are enclosed in valves, four in some kinds 

 and five in others, and they are either sessile (immoveably attached) or 

 peduncular (can swing like a clock pendulum when attached to a particular 

 spot). The Sessile family (Acamptosomata of Leach) have their four valves 

 contained in a short calcareous tube, upper end open, lower closed either 

 by membrane, as in Coronula (Plate 9, fig. 7), or by earthy matter, as in 

 Balanus (/&. fig. 12) : in either case this base is penetrated by little conical 

 chambers, side by side, into which processes of the mantle pass, and fix the 

 tube to the rock ; whilst the moveable valves are supported on the upper 

 part of the mantle. In the Peduncular family (Camptosomata of Leach), 

 a long pedicle or foot proceeds from the mantle as it shuts up the lower 

 aperture of the five valves, as in the Barnacle, Pentalasmis (Ib. fig. 3). 

 The pedicle is covered externally with a hard horny cuticle, and contains 

 within a mass of muscular fibres attached by one extremity to the bottom 

 of the mantle, and by the other to its own base, by which it fixes itself. 



ORDER PEDUNCULAR. CAMPTOSOMATA. 



ILLUSTRATIVE EXAMPLES. 

 PLATE 9. 



PENTALASMIS. Shell conical, subtriangular, composed of five valves ; 

 animal compressed, peduncle elongated. This genus of Cirrhopods are 

 found attached to wood floating on the sea; they are distinguished by 

 numerous valves, and by their very much elongated pedicle. They consti- 

 tute the genus Anatifera of Lamarck, and the fapas Anatifer of Linnaeus. 

 They are generally to be found in most seas, and are abundant off the coast 

 of Africa. They attach themselves to the bottoms of ships. 



Illustration : Pentalismus mdgaris. 



CINEP.AS. Body pednnculated, wholly enveloped in a membranaceous 

 tunic, which is turgid, and open in front beneath the apex ; arms numerous, 

 slender, articulated, ciliated, protruded at the aperture; shell consisting of 

 fivn testaceous oblong valves, which are separate, and do not wholly cover 

 the Ixxly ; two placed at the sides of the aperture, the others at the back. 



This genus was established by Dr. Leach, and, with the genus Otion, 

 to which it is somewhat allied, forms the family Clytidii. 



Illustration and type : Cineras vittata. 



OTION. Body supported on a tubular (xxluncle, enveloped in a mem- 

 branous tunic, ventricose above, with two tubes disposed in the form of 

 horns directed backwards, open at tlu-ir extremity, truncated and placed at 

 the summit of the tunic ; a lateral opening, with many articulnt' 

 arms ; shell with two small testaceous semilinear valves, adhering near the 

 lateral opening. 



Illustration and type : Otion Cuvieri. 



Inhabits the Northern Ocean, and has been found on the southern coast 

 of England. 



SCALPELLUM. Shell flat, quadrated, composed of thirteen valves, six on 

 each side and one dorsal ; pedicle short and scaly. 



The animal of this genus resembles that of IVntalasmis. There are two 

 species, one of which is found in the Straits of Magellan, and the other is 

 common in the European seas. 



Illustration : Scalpdlum vulgare. 



POLJJCIPES. Body supported on a long, tubular, tendinous, peduncle, 

 covered by a shell, composed of numerous unequal valvular plates, ihirtivii 

 or more in number, and the smallest placed low on tho sides ; the peduncle 

 itself dotted with rounded cimbriated scales. 



Illustration and type : Pollicipes cornucopia. 



Found in the seas of Europe and Britain ; not very abundant in the latter 

 country. 



ORDER SESSILE. Ac AMPTOSOMATA. 



ILLUSTRATIVE EXAMPLES. 



TOBICINELLA. Shell univalve, operculated, tubular, straight, slightly 

 attenuated towards the base ; banded circularly with transverse ribs, trun- 

 cated at both ends, open at the top and closed by a membrane at the base ; 

 opercule consisting of four unequal valves ; the inclosed animal projects from 

 the upper aperture; small, unequal, setaceous cirrhi. 



The shell of this genus differs from that of all the other Cirrhipeds; it 

 appears open at both extremities, but during the life of the animal its lower 

 extremity is closed by membrane. The valves of its opercule are trapezoid, 

 obtuse, and moveable, inserted in the upper part of the inner wall of tho 

 shell. The animal attaches itself to the bodies of whales, and as it grows 

 penetrates through the skin to the subjacent fat. 



Illustration and type : TubicineUa Lamarckii. 



CORONULA. "Shell subcylindrical or subconic, depressed; base much 

 wider than the apex ; lips of the operculum very prominent, with two large 

 shelly valves before, and one small one on each side of the legs." Leach. 



The opening of these shells is always regular, elliptical, slightly hexagonal ; 

 and the valves of the operculum, which rather belong to the animal than to 

 the shell, are inserted near the base of the internal parictes of the shell. 

 The substance of the shell is divided in the interior into a number of cells, 

 separated by their shelly plates, and arranged in a radiated position. The 

 base is not closed by a calcareous plate, but by a membrane formed by the 

 aatmaL 



The Coronula;, like others of the family, are generally found on the surface 

 of inurino animals, as Whales, Turtles, &c., and they partially bury the base 

 of the shell in tho skin of the animal to which they :\re fixed, when; it is 

 siillieiently soft. 



Illustration : Coronula diadema. 



PYROOMA. A single conical shell, compressed and thick ; hollow ] 

 with a small aperture, closed by an operculum of tw> v;il\. nf variable 

 form; supported by a cup-shaped base; grooved | rpm.lictilarly within. 



This genus has been established by S.-ivigny; it may be dist 

 from Creusia by the parietal cone, which is simple and not divided into 

 valves. It is found attached to Corals. 



Illustration : Pyrgama canceUata. 



CUKUSIA. Body sessile, subglobose, enclosed in an operculated shell; 

 three or four pairs of tentaculiform arms ; mouth at the upper and anterior 



