CYRTOCERAS. 105 



Siphuncle small, situated nearly but not quite close to the ventral margin. 

 Surface ornamented with between twenty-five and thirty low, blunt, longitudinal 

 ribs, separated by wider intervals, and crossed by regularly undulating mem- 

 branaceous frills or flounces, set nearly perpendicularly, advancing towards the apex 

 in the hollows and receding on the ribs. Ventral area marked by a wider (and 

 perhaps slightly convex) interval between the two central ridges, and by an extra 

 advance of the frills. 



Size. — The approximate measurements of a specimen, which wants the body- 

 whorl, are length, 60 mm; depth, 18 mm. ; width, 24 mm. 



Locality. — Wolborough. One of Phillips's figured specimens is in the British 

 Museum. There is a finely preserved portion of the upper part of the shell in 

 the Battersby Collection in the Torquay Museum, and three other specimens, one 

 of the oral and two of the apical portions, in the Museum of Practical Geology. 



Bernarls. — I have been unable to find the more distinctive specimen of the two 

 which Phillips figured ; but, although evidently somewhat roughly and mis- 

 leadingly drawn, there is no doubt of the present identification. The number of 

 longitudinal ribs is stated by Phillips as fifteen, but his figure shows that there 

 must have been between twenty and thirty upon his shell. ^ On the other hand, 

 Phillips states the section to be elliptic, although this would not have been 

 discovered from the figure. Of the figured specimen in the British Museum 

 Mr. Foord remarks that it is far too imperfect " for any comparison of it to be 

 made with other species. More than half of it is buried in the rock, and what is 

 visible has been much decomposed by weathering." It is, moreover, not 

 accurately represented by Phillips's figure, as the lamellae are not so elongate or 

 so perpendicular to the whorls as there shown, but agree with those of our other 

 specimens, and its curvature is also less. 



Comparing the specimens mentioned above, this species seems very variable, 

 and there would seem some reason for questioning whether it is really distinct 

 from G. quindecimale on account of the passage between them. It may therefore 

 be well to notice some specimens of the two species in detail. 



(1) The specimen of G. jimhriatum figured on PI. X, fig. 4, is altogether like 

 Phillips's fig. 214 b. Its apex is wanting. 



(2) The specimen of G. fimhriahmi figured on PI. X, fig. 3, is similar, but is 

 much worn. Its frills are as coarse, and it shows the apical end and the rate of 

 tapering. Its section is much more circular, and thus approaches that of 

 G. quindecimale. 



(3) A large specimen of G. fimbriatum, showing the dorsal side of the oral 



^ It is probable that only a portion was exposed, and that thus he has under-estimated the number 

 of ribs, for if his figure is to be trusted both this species and C. quindecimale must have bad consider- 

 ably more than the number he states. (Eight or nine are shown on the exposed face of each.) 



