440 



extante spiruli fortiori, anfr. circiter xii. defin&ente, nucleum 



casus obsoleta ; intus umbone satis prominente, superjicie stri- 

 u/is minimis concentricis ornata. 



Variat apice parum seu valde elevato. 



Test, adult, gibbosa, long. "063, lat. "013 — •022 ; div. sept, et 

 apert. 130°. 



Test, adult, normalis, long. "067, lat. *013 — *02 ; div. sept, et 

 apert. 105°. 



Test, adult, elongata, long. -082, lat. -016 — '022 ; div. sept, et 

 apert. 105°. 



About 240 specimens have been examined, of which three pos- 

 sessed their opercula. In one, the spiral raised bar is distinctly 

 traceable to the very apex ; in another it is only seen for about eight 

 whorls. The same difference is recorded under Brochina glabra*. 

 The shells go through the same changes of form as in the last 

 species ; and many specimens display the same "crinoline" pattern 

 in the transparent and opake banding. It is in general easily 

 distinguished by the shape of the plug, which, even when the apex 

 is but slightly raised, is still somewhat tumid, while in M. cornucopia 

 the lateral outline is concave. Aberrant specimens exist in all the 

 species which cannot be discriminated with confidence. It is possible 

 that the forms with the high pointed plug belong to a fourth species, 

 perhaps a Fartulum, allied to C. teres ; but they have here been 

 distributed among the rest according to the balance of characters. 



Genus Strebloceras-)-. 



Testa hand decollata ; vertice nucleoso orbiculari, plana tuber- 

 culari perpendiculariter affixo. Habitus increscentis plerum- 

 que orbicularis, seu subtortuosus. 



This earliest known Csecid preserves in its adult state the first 

 stage of Cezcicm, — the whorls not being decollated, nor any plug 

 formed. The shells are too large and too numerous to be supposed 

 rudimentary, especially when the extreme rarity of the " Cornu- 

 oides " form even in recent Cceca is taken into consideration. It 

 bears the same relation to Ceecum that Rimula does to Glyphis\, and, 

 as far as the shell is concerned, forms an easy passage to Vermetus. 

 The plane of growth is generally flat, as in Ceecum ; but some spe- 

 cimens have a slight twist, forming an approach to Meioceras, In 



* Having succeeded in extracting one of the opercula, -018 in diameter (in 

 which the concavity was about -002, the inner boss about "001), I was surprised 

 to find, on the second day's examination, that it presented fewer whorls, and those 

 further apart, than before. On investigation, it appeared that the whole margin 

 had bent over inwards, giving the object the appearance of an elf's " wide-awake " 

 hat. The tiny article was then caused to balance on its reflected margin, in 

 which position the strong ribs presented much the appearance of the lost opercu- 

 lum described under Ceecum bimarginatum. 



+ <TTpcj3Xbs, twisted ; icepas, horn, 



X B.M. Maz. Cat. pp. 213, 220 = Lucapina, pars, II. & A. Ad., non Gray, = C'a- 

 piluna, Gray, Guide Moll. 1857, p. 1C6. The proof sheets of the Maz. Cat., bear- 

 ing date May 1856, were submitted to Dr. Gray's inspection. 



