CYRTOCERAS. 103 



1842. Cyetoceeatites lamellosus, D'Arch. and de Vern. G-eol. Trana., ser. 2, 



vol. vi, pt. 2, p. 348, pi. xxviii, figs. 4, 4 a, h. 



1849. Ctbtoceeas quindecimalis, (POrh. Prodrome, vol. i, p. 53. 



1850. — XTNDTTLATUM, F. A. Romer. Beitr., pt. 1, p. 18, pi. iii, figs. 



25 a — c. 

 1852 ? — LAMELLOSUM, Sandberger. Verst. Rbein. Nassau, p. 144, 



pi. XV, figs. 3 a, h. 

 1852. — QUiNDECiMALE, Qielel. Fauna Vorwelt, Band 3, Abth. 1, 



p. 205. 

 1879. — MOESTTM, fiaZ/. Pal. N, Y.,vo]. V, pt. 2, p.367,pl.xlvii,figs. 4,5. 



1888. — — Etheridge. Foss. Brit., vol. i. Pal., p. 167. 



1888. — ? — Foord. Cat.Foss.Ceph. Brit.Mus.,vol.i,p. 318. 



Bescription. — Shell more or less arched, tapering. Section elliptic ; ratio of 

 ventro-dorsal to transverse diameter as 15 : 18. Siphuncle close to ventral 

 margin. Body-chamber at least about one-third of the shell. Walls of chamber 

 definitely concave. Surface with twenty-five to thirty very indistinct longitudinal 

 ribs, crossed by numerous close and prominent frills or membranaceous flounced 

 ridges, which are divided occasionally by larger grooves so as to show a tendency 

 to fall into sets of four or five, or in some specimens have every third or fourth 

 ridge rather stronger. Ridges becoming obscured and apically deflected as they 

 cross the siphuncular area. 



Size. — Length, 55 mm. ; width, 18 mm. 



Locality. — Wolborough. There are two specimens in the Battersby Collection 

 in the Torquay Museum, a third in Mr. Vicary's Collection, a fourth, which is 

 supposed to be Phillips's type, in the Museum of Practical Geology, and one in 

 the Lee Collection in the British Museum. 



Remarks. — I do not feel certain whether the fossil in the Museum of Practical 

 Geology is really the type from which Phillips's figure of the species is drawn. In 

 the records of the Museum it is only treated interrogatively, and it certainly is 

 very different from both his figure and description, and in fact differs far more 

 from that than it does from G. lamellosus, d'Arch. and de Vern., especially in the 

 distinctive points to which the latter authors draw attention. I have, in fact, no 

 hesitation in regarding this German shell as belonging to the same species. The 

 only difference between it and the Jermyn- Street fossil is in size, in the rather 

 greater relative number and fineness of the frills, and in the presence of a still finer 

 series of stris3 between them. The state of preservation, however, of the English 

 specimens would not permit of the latter character being preserved, supposing it 

 to have been originally present in them. 



The species seems to be very variable, both as to the curvature of its 



profile and as to the number and coarseness of its markings. More than this, the 



Battersby fossil shows to how great an extent the latter character may change in 



a single specimen. This specimen, which is far more like Phillips's figure, 



14 



