TROCHOCERAS. 85 



2. Trochoceeas Vicarii, Whidborne, sp. PI. IX, figs. 1, I a, lb. 



? ? 1844<. Ctetoceratites mtjltisteiatus, F. Bomer. Ehein. Ubergangsg., p. 81, 



pi. vi, figs. 3 a, h. 

 1889. Ctetocebas Vicakii, Whidh. Geol. Mag., dec. 3, vol. vi, p. 29. 



Description. — Shell medium-sized, very rapidly increasing, coiled in a little 

 more than a volution, leaving a wide, open, elliptic central space. Section 

 nearly circular, becoming subquadrate on the body-whorl. Chambers apparently 

 rather narrow ; surface ornamented with very numerous, fine, sharp, longitudinal 

 striae, which seem imbricated by much more numerous indistinct transverse strige, 

 and bearing on the side, just below the shoulder, a row of very distant large bluntly 

 conical nodules, which are elongated longitudinally, and point outwards, from 

 which very indistinct bulges cross the sides, tending rather forwards, and 

 becoming rather more prominent as they turn inwards to the dorsal side, where 

 they probably vanish. Apex very small. 



Size. — Length, 63 mm. ; width, 51 mm. ; depth, about 30 mm. 



Locality. — Wolborough. A single specimen is in Mr. Vicary's Collection. 



Bemarhs, — Mr. Roberts and I have come to the conclusion that this specimen 

 must be separated from the succeeding species, chiefly on account of the position 

 and fewness of its lateral tubercles. At the same time it is evidently very closely 

 allied to several of the adjacent forms. 



It comes so close to Gyrtoceratites multistriatus, F. Rom.,^ that I am in a little 

 doubt whether it may not prove ultimately to be only a variety of that shell. 

 The nodes, however, in the English form are fewer, being only four where the 

 German fossil has seven ; and the longitudinal stri« do not seem so numerous, and 

 are, moreover, crossed by much more frequent, though indistinct, transverse 

 striae. There are no marks corresponding to these transverse lineations in 

 Romer's figures, but it is possible that they may have been overlooked if his 

 specimens were not well preserved, as they can only be observed with difficulty 

 in ours. 



The shell described by Barrande under the name Troehoceras nodosum^ evidently 

 belongs to the same group, agreeing in a general way in the possession of nodes, 

 the fine ornamentation, the slight asymmetry, the sub-quadrilateral section, and 

 the position of the siphuncle. While, however, there is clearly a generic identity 

 between the two shells, there is as clearly a specific difi'erence. The spire of the 



1 1844, F. Eom., ' Rhein. Ubergaugsgebirges,' p. 81, pi. vi, figs. 3 a, b. 



2 1865, Barrande, ' Syst. Sil. Boheme,' vol. ii, p. 110, pi. xx, figs. 18— 23, and pi. xxv, tigs. 7—18, 

 fit. E. 



