540 L. F. Spath — A iieiv Amnion if e froni Cliarraoidli. 



also shown in specimen C 18836. Fig. Ih is a restored outline- 

 section. 



The umbilical edge is somewhat abrupt and the slope is flattened 

 where the costa; describe the peculiar bend shown in Fig. 4. The 

 involution is very slight, which character, together with the peculiar 

 costation, gives these forms a lytoceratid aspect. A specimen 

 from the Crumbly Bed. shown to the writer by Dr. Lang, is in fact 

 a (poorly preserved) Fimhrilytoceras. 



Owing to the difficulty of removing the (limonitic) remains of the 

 shell from the interstices between the ribs, the suture-line could not 

 be exposed satisfactorily. Fig. \c is composite, made up from 

 portions of several suture-lines at a diameter of 65 mm., i.e. about 

 a third of a whorl from the end of the shell. Since there are traces 

 of the suture-line still at the end, the specimen complete with its 

 body-chamber must have been over 120 mm. in diameter. 



Specimen 3770 (Coll. W. D. Lang), from the Pyritic Marls, 16 inches 

 below the Belemnite Stone at Westhay Water, 1| miles east of the 

 mouth of the River Char, is nearly complete, though crushed, and at 

 a diameter of 90 mm., has : — 



Height of the last whorl . . . 3.3 ""j^. 



Umbilicus ...... 44 j^. 



The thickness of the shell is 22 per cent in the one place where there 

 is no compression, so that there can be no doubt that the specimen is 

 specifically identical with the type. The costation is just a trifle 

 closer, however, since there are about 125 ribs on the last w^horl. 

 It may be added that, though the innermost whorls are not preserved, 

 the peculiar costation of the species is already shown at a diameter 

 of 15 mm. 



Since traces of what probably was the last suture-line are shown 

 at a diameter of 80 mm., the complete shell must have been con- 

 siderably larger than the preserved portion. At this spot also (just 

 before the commeiicemcnt of the crushed body-chamber) parts of 

 the shell are preserved on the periphery. The median row of 

 tubercles was much more distinct on the shell than on the pyritic 

 cast, and the rounded jirominences composing it alternate in position 

 with the thickened and forwardly-bent terminations of the lateral 

 ribs. A very indistinct ridge in the shape of a A seems to connect 

 the three lines of tubercles across the periphery. 



Si:)ecinien 3769 (Coll. W. D. Lang), from 12 inches below the 

 Belemnite Stone, Cliff Base, south-west of Golden Cap, consists of 

 half a whorl of an Ammonite about 47 mm. in diameter. The 

 specimen is partly crushed, but typical and extremely finely costate. 

 It clearly shows the prominent median line of tubercles on the 

 periphery, but the two lateral rows of tubercles are irregularly 

 crushed against it in places. The specimen is not pyritized, as the 

 others are, but preserved in the peculiar pyri tic-marly matrix of its 

 bed, and like other fragmentary fossils from this horizon suggests 

 disturbed deposition. 



