136 PROCEEDINGS OF TUE MALACOLOGICAL SOCIETY. 



detached, the corresponding groove on the posterior surface of the 

 internal cast being most probably due to the thickening produced 

 where the septum meets, and is, as it were, fused to the shell-wall. 

 On the lower part of the dorsal surface of the internal cast of the 

 body-chamber, at about 6 mm. from the last septum and a little to 

 the left of the median line, a curved line {sm in Figs. 1 and 2) 

 originates ; this passes upwards and a little to the right, until it 

 is 12 mm. from the septum, when, continuing its upward course, it 

 bends slightly to the left until it is 32 mm. from the septum, when 

 it curves at first outwards and then backwards, until it is about 1 6 mm. 

 from the last septum ; then it appears to divide ; one part continues 

 on towards the last septum, for a short distance, and then disappears, 

 the other turns almost horizontally, and soon passes beneath a portion 

 of the test. This curved line, just described, thus forms part of the 

 boundary of an ellipse, of which the major and minor axes are 32 

 and 20 mm. respectively, the major axis being directed forwards and 

 inclined towards the median line of the dorsal surface. In a corre- 

 sponding position on the right side of this surface there appear to 

 be indications of a similar elliptical area,' meeting the one on the left 

 at a place a little to the right of the median line, but the fossil is 

 here so much weathered that the course of the boundary of the area 

 cannot be satisfactorily followed. These areas are believed to be the 

 muscle-scars, and the short horizontal branch proceeding from the one 

 on the left appears to be the anterior boundary of a part of the annulus. 

 I have not been able to find any record of a similar Nautiloid from 

 the Carboniferous rocks. It cannot possibly be referred to any of 

 the described species of Nautiloidea recorded on pp. 261 and 262 of 

 Mr. G. ^Y. Lamplugh's work on " The Geology of the Isle of Man " 

 (Mem. Geol. Surv.), published in 1903. In the list of Carboniferous 

 fossils (named by Count Keyserling) from the Isle of Man, given by 

 the Rev. J. G. Gumming on pp. 354-359 of his work on " The Isle 

 of Man," published in 1848, besides a number of Nautiloidea which 

 had already been described, the following new species are mentioned : — 

 Cyrtoceras Foohashi, from the Poolvash Limestone ; C. tessellatum, 

 from the Posidonomya Beds ; Orthoceras cMetes, from the Posidonomya 

 Beds; and 0. prolongatum, from the Poolvash Limestone and Posido- 

 nomya Beds. No descriptions of these fossils are given. The only 

 species which seems likely to have been the one here described is 

 Cyrtoceras Poolvashi. Possibly the examples of these new species 

 were in the Gumming Collection, which is still preserved in the 

 Museum of King William's College at Castletown, Isle of Man, but 

 Mr. Lamplugh states {op. cit., p. 251) that, when he saw the 

 collection, it had fallen into disorder, so that the majority of the 

 specimens were then either without labels or with labels insufficient 

 for their identification, and, further, it was suspected that the labels 

 had in some cases been shifted from their original specimens. Under 

 the circumstances, therefore, it appears to be now impossible to 

 identify these species, and the names must remain nomina nuda. 



' Indicated bv the dotted line in Fiff. I . 



