96 ME. G. C. CRICK ON THE MUSCULAE ATTACHMENT OF THE 



The outline of the musculav impression is also well shown in another example of this 

 species from the Lower Lias, near Whitby, in the collection of F. L. Bradley, Esq., F.G.S., 

 of Alderley Edge, Cheshire, to whom I am greatly indebted for the loan of the specimen. 

 The impression has the same form and position as that already described in the example 

 from the Lias of Cheltenham, which is in the British Museum Collection (No. 67929). 

 The specimen is in the centre of a nodnlc ; its dimensions, so far as can be ascertained, 

 are as follows : — diameter of shell 65 mm. ; width of umbilicus 31 mm. ; height of 

 outer whorl 16 mm. ; ditto at base of body-chamber 13 mm. The last half-whorl is 

 occupied by the body-chamber, the exposed portion of which is almost completely 

 denuded of the test ; at its base and on the inner portion of the whorl the outline of the 

 muscular impression can be seen. The anterior convex boundary of the impression is 

 5"5 mm. in advance of the last septum, the width of the impression from the suture of 

 the shell being 2 mm. 



There is no trace of the annulus, and the perijiheral portion of the fossil is obscured 

 by matrix. 



JEgoceras laqueolum, Schloenbach, sp.* — In an example of this species from the 

 Lower Lias of Harbury, Warwickshire, in the British Museum Collection (No. C. 6619), 

 one of the muscular scars is well displayed. The specimen consists of about three-fourths 

 of a whorl 165 mm. in diameter, and is a natural cast of part of the body-chamber. 

 The base of the body-chamber is complete : it is 24 mm. high ; 30 mm. wide including 

 the ribs, or 29 mm. excluding the ribs. The muscular scar, which is clearly seen at the 

 base of the chamber, is situated partly on the lateral area and partly on the impressed 

 zone (PI. 20. figs. 3, 4). The faintly-incised line bounding the scar arises from the last 

 sejitiim at a point 4"5 mm. from the inner edge of the whorl ; then, passing forward for 

 a length of about 9 mm. nearly parallel to the inner edge of the whorl, it turns towards 

 the impressed zone, becomes much more distinct, and crosses the inner edge of the whorl 

 13 mm. in advance of the last septum ; passing on to the impressed zone with a rather 

 broad sweep, it gradually disappears, but the form of the scar is indicated by a difference 

 in colour, the impression being a little darker than the surrounding surface. The 

 impression did not quite reach the middle of the impressed zone ; it appears to have 

 been elliptical in form, about 15 mm. long and 11 mm. wide, the larger portion being 

 situated on the impressed zone. On the anterior portion of that part of the scar which 

 is situated on the imjjressed zone there is an exceedingly faint line, concentric with the 

 anterior border of the scar, which evidently marks a former attachment of the anterior 

 border of the shell-muscle. 



Only a very small portion of the other scar is visible ; this is on the impressed zone. 

 The greater part of the imjn-ession is obscured by matrix. 



There is no trace of the annulus. 



* raltcontogr. vol. xiii. pi. xxvi. f. \ = CaJoctras Uaskwn (d'Orbigny), _^c?e Hyatt, Geu. Arietida:, p. 139. 



