220 Messrs. A. H. Foord and G. C. Crick on Muscular 



XXXI. — On the Muscular Impressions of some Species of Car- 

 boniferous and Jurassic Nautiloids compared with those of 

 the recent Nautilus. By Arthur H. Foord, F.G.S., and 



G. C. Crick, Assoc. R.S.M. 

 Museum (Natural History). 



F.G.S., of the British 



In the 'Geological Magazine* for November 1889 we 

 described and figured the impressions of the shell-muscles 

 of Coelonautilus cariniferus, J. de C Sowerby, sp.*, from 

 the Carboniferous Limestone of Ireland. We have since 

 had the good fortune to meet with other species in the 

 British Museum Collection, both of Carboniferous and Jurassic 

 Nautiloids, in which similar impressions are more or less 

 completely preserved. 



In the figures a indicates the anterior boundary of the mus- 

 cular impression, p the posterior, and s the last-formed 

 septum. 



The accompanying figure (fig. 1) f of a cast J of the 

 interior of the shell of a recent Nautilus (N. pompilius) is 



Fig-. 1. 



here introduced for comparison with the fossil forms to be 

 described below. Upon the side of the body-chamber is 

 seen the impression of the ear-shaped shell-muscle, together 

 with part of the " annulus " or band that connects it with 



* Min. Conch, vol. v. 1825, p. 130, pi. cccclxxxii. fig. 3 (excl. fig. 4). 



f Figs. 1-4 inclusive were all drawn on a reduced scale with the camera 

 from the original specimens. 



\ To obtain the cast, the shell having been longitudinally sectioned, 

 one half was filled with paraffin and then immersed in dilute hydrochloric 

 acid until the shell was completely dissolved. 



