CEPHALOPHORA. 101 



paled in.) Order, Sessile Cirripedes, Lam. — Descr. Light prin- 

 cipal valves, cemented side by side in a circle ; eight small 

 pointed valves beneath, covering the joints of the upper circle, 

 and numerous still smaller valves forming the base of the shell ; 

 operculum, four valves. — Obs. This is the only genus of Sessile 

 Cirripedes, consisting of eight principal valves, excepting Octo- 

 meris, which is destitute of the accessary pieces from which the 

 genus derives its name. Fig. 23. C. imbricatus. South Africa. 



CAUDAL CANAL. The elongated hollow process which terminates 

 the aperture anteriorly of some univalve shells. For instance, 

 Murex Haustellum, fig. 396, has an elongated caudal canal. 



CELLANTHUS. Montf. Vorticialis, Bl. A genus of mi- 

 croscopic Foraminifera. 



CELLULACEA. Bl. The second order of Cephalophora, Bl. 

 consisting of doubtful microscopic bodies, with a number of 

 variously arranged shells, as distinguished from the true Poly- 

 thalamia, Bl. or chambered shells. See Foraminifera. 



CEMORIA Flemingii. Leach. A small patelliform shell, dif- 

 fering from Fissurella, in having the fissure placed behind the 

 apex, which is produced, pointed and incurved. It is the Patella 

 Fissurella, Mull. Patella Noachina, Chemn. F. Noachina, Sow. 

 Puncturella, Lowe. Fig. 244. Cemoria Flemingii. Scotland and 

 Tierra del Fuego. 



CENTRAL. A term used to indicate the position of the muscular 

 impression of a bivalve shell when it is near the centre of the 

 inner surface. It is also applied to the siphon perforating the 

 septum of a chambered shell when it is placed near the centre of 

 the plate. &«5-central is also used as a comparative term, to 

 indicate the position of the siphon, or of the muscular impres- 

 sion, is near the centre. Thus in Placuna(fig. 184), the muscular 

 impression is central : in Exogyra (fig. 183), it is sw6-central. 



CEPA. Humph. Anomia, Linn. 



CEPHALOPHORA. Bl. The first class of Malacozose, Bl. Di- 

 vided into: Order 1. Cryptodibranchiata ; 2. Cellulacea ; 3. 

 Polythalamacea. The first consisting of Cuttle-fish, &c. which 



