ANJMAL TO ITS SHELL IX SOME FOSSIL CEPHALOPODA, 89 



Cardioceras sj). — Indications of the muscular attachment are well displayed in a small 

 Ammonite from the Upper Jurassic of Kintradwell, Sutherland, which forms part of the 

 British Museum Collection (No. C. 4389). Although the specimen is fairly well pre- 

 served, I have not been able satisfactorily to determine the species, but it seems to be 

 referable to the genus Cardioceras (PI. 19. figs. 3, 4). Its dimensions are as follows : — 

 diameter of shell 235 mm. ; greatest thickness 8'5 mm. ; width of umbilicvis 7 mm. ; 

 height of outer whorl 8 mm. The last two-fifths of the outer whorl are occvipied by the 

 body-chamber ; the test having been removed from the left side and from the periphery 

 of this portion of the whorl, the internal cast is weU displayed. Unfortunately only a 

 small portion of the last suture-line can be made out, the rest being obscured by the 

 test. The portion of the last septum adjacent to the suture of the shell is obscured, but 

 on the internal cast of the body-chamber, at a short distance anterior to the last septum, 

 a very fine incised line arises from the suture of the shell, passes inward in an almost 

 radial direction for about 2'5 mm., then turns I^ackward for about 0-5 mm., and again 

 resumes its radial direction across the whorl, being feebly depressed as it passes over each 

 lobe, and slightly raised in passing over each saddle; it is about 0"5 mm. above the 

 lateral saddle and almost touches the most anterior portion of the external saddle. As it 

 approaches the periphery it lu^rns forward to join a somewhat peculiar-shaped roughened 

 scar represented in fig. 4, the posterior inflated portion of which is rather rougher than 

 the rest. Unfortunately the opposite side is obscured by matrix. The perijihery of the 

 posterior portion of the body-chamber seems to be somewhat deformed, and to possess a 

 feeble keel with a shallow sulcus on either side ; this deformation may account for the 

 median division of this scar, which probably was originally horseshoe-shaped, as observed 

 in several otlier Ammonoids. 



The portion of the incised line near the suture of the shell doubtless represents the 

 position of the anterior border of one of the shell-muscles, the rest of the line indicating 

 the position of the anterior boundary of the annulus, there having been, in addition, a 

 firm attachment at the centre of the 2:)eriphery. 



Neumaykia, Xikitiu. 

 Nenmayria catenulata, Fischer, sp. — In the British Museum Collection there is an 

 example of this species exhibiting the form of the muscular attachment. It is a badly- 

 cruslied internal cast from the Portlandian of Choroschowo, near Moscow, Russia. The 

 specimen is 119 mm. in diameter, the width of the umbilicus (from suture to suture) being 

 18 mm., the height of the outer whorl 58 mm., and its thickness 26 mm. The inner area 

 of the whorl slopes towards the umbilicus and at the base of the body-chamber is 6 mm. 

 wide, the height of the whorl here being 43"5 mm., and its greatest thickness, which is at 

 a short distance from the umbilical margin, 15-5 mm. Tlie last two-thirds of the outer 

 whorl are occupied by the body-chamber. The whorl is sagittate in cross section. The 

 muscular impression is well shown on one side, but tlie crushed condition of the specimen 

 has obliterated it on the other side. Arising from the suture at about 7 mm. from the 

 base of the l)ody-chamber, the boundary of the impression, in the form of a faintly-indented 



13* 



