CECUM. 7.") 



In his ' History of British Animals ' Fleming placed 

 these shells in Orthocera (Orthoceras, a genus of fossil 

 testaceous Cephalopoda), along with recent Foraminifera; 

 and he thus drew on himself from Philippi perhaps the 

 most severe reproof that could be administered to a 

 naturalist, in the comment " horribile dictu." The censor 

 himself classed them among the Pteropods ! Montagu 

 called the adult Dentalium, and the young Vermiculum ; 

 Brown gave the name of Brochus to the former, and 

 Cornuoides to the latter. Other synonyms are Odou- 

 tina, Zborzewsky, Odontostoma, Cantraine, Odontidium, 

 Philippi, Corniculina, Minister, and Dentaliopsis, Clark. 

 The fry constitute Costa's genus Spirolidium. 



A. Solid and ringed ; operculum flat. 

 1. Cecum trachea * Montagu. 



Dentalium Trachea, Mont. Test. Br. p. 497, t. 14. f. 10. C. trachea, F. 

 & H. iii. p. 178, pi. Ixix. f. 4, and (animal) pi. KK. f. 1, a-c. 



Body white, minutely grained, with two frosted, pale-yellow- 

 ish-white contiguous raised lines on the upper part, forming a 

 canal or groove, the points of which terminate anteriorly at 

 the immediate base of the eyes, and posteriorly at the furthest 

 end of the neck : mantle very thick and fleshy : neck slender, 

 ridged lengthwise : snout long, flat, and cloven, witji fine, close, 

 contractile annular ridges ; it is always in advance of the foot, 

 and appears to assist in locomotion : tentacles frosted-white, 

 rather long, divergent, at the extremities thickened, setose, 

 and slightly clavate : eyes very minute and black ; they " have 

 decidedly an external bias " (relatively to the position of the 

 tentacles) : foot narrow, truncated in front when in .action, 

 sloping behind to an obtusely pointed or rather a rounded ter- 

 mination. (Clark.) 



Shell of nearly equal breadth throughout, solid, opaque, 

 and somewhat glossy : sculpture, numerous fine, regular, and 



* From its being marked with rings like a windpipe ; the Latin word 

 is properly trachia. 



E 2 



