423 



resembles a Dumber of polygonal tint tiles piled <>iie on another. The 

 concentric sculpture is strongest in the young shell, the longitudinal 

 in the adult. Thirty-three specimens nave been Kamined. 



Sect. B. Anki.i.t if. 

 Cceca typiea; t. adulta annulata. 



That this is the typical condition of the genus is Bhown b) the 

 tendency that shells in the other groups have to assume the rii 



character, especially about the mouth. 



11. Cecum annulatum, Brown (diagn. auct.). 



C. (Anellum) t. mqjore, elongata, sol id a ; annuUs validu v 

 xxx., rotundatis, extantibus, eincta, plerumque distantioribut, 

 prcesertim aperturam versus; lirulis longitudinalibu 

 minimis, eztantibus, et interstitia et annulos trarweuntibtu . 

 si- j, to mucronato, margine laterali concavo ; n tbiter 



ascendente, valido, dactylifortni, subdextrorsvm sito ; t.ju\ 

 annulis acutioribus, lirulis obsoletis : operculo ? 



Test. jun. long. -053, lat. -008— '014. 



Test, adolesc. long. -108, lat. 016— -035. 



Test, adultse long. "122, lat. 022 — -035. 



Hab. [South Coast of England (Alder) ; Killough, Lough Str. 

 ford, Ireland (Brown)'] ; W.Indies, sponge of commerce ; Aden 

 (Bean, MS.). Mus. Brit. &c. 



Brochus annulatus, Brown, 111. Conch. Gr. Br. 18-14, p. 125. 

 pi. 56. f. 12. 



+ Brochus reticulata, Brown, loe. cit. p. 124, pi. 50. f. 11. 



Ceecum annulatum, Forbes & Ilanlev, Br. Moll. vol. iii. p. 181. 

 pi. 88. f. 7. 



Orthocera trachea (pars), Flem. Hist. Br. An. 1828, p. 237 

 [uon Dentalium trachea, Mont.]. 



The name reticulation would have been far more characteristic <>t 

 this beautiful species; but as it was given to the adolescent state, 

 and annulatum to the adult, which is well figured in the Br. Moll., 

 the latter is retained. Fifty-three specimens of various ages have 

 been examined from the W. Indian sponge, and have been carefully 

 compared with Mr. Alder's supposed British specimen. This has the 

 posterior rings much closer than usual. The characteristic longitu- 

 dinal threads, which reticulate both the rings and the hollows, are 

 scarcely seen in the young shell, which, even in the earliest - 

 found, is distinctly and somewhat sharply ringed. In this State it 

 is known from C. regulare by the very prominent finger-shaped 

 mucro. Many adult specimens were found having an additional 

 ring remaining beyond the plug; bul even then the mucro is con- 

 spicuous. 



The Aden specimens are too much rubbed to determine with • 

 fidence; but in the mosl perfect the characteristic fing 

 mucro, the reticulated sculpture, and the thickened distant 



