ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 97 



JEgoceras Portlocli'd, Wright. — An example of tliis species from the Boulder Clay of 

 Ireland (exact locality iinkuown) was sent to me hy Dr. A. H. Foord for determination. 

 It was in a reddish matrix. It is a natural cast of the posterior portion of the body- 

 chamber, showing not quite the complete suture-line at its base, and bearing only 

 fragments of the inner portion of the test. The length of the fragment measured on the 

 periphery is just over 70 mm. ; the whorl is nuich comjjressed, nearly twice as high as 

 wide ; the transverse section of the whorl is elongate-oval, its gi'eatest thickness being at 

 about one-third of the width of the latei'al area distant from the suture (of the shell). 

 The impressed zone on the inner side of the specimen shows that the indentation 

 by the preceding whorl was very slight, and that the periphery of the jjreceding 

 whorl was more acutely convex than that of the outer Avhorl. At the base of 

 the body-chamber the height of the whorl is 33'5 mm., and the greatest thickness 

 about 18 mm. Any indication of the muscular attachment that may be preserved 

 on the surface of the impressed zone is obscured by portions of the test, but on 

 each side of the inner portion of the lateral area of the posterior jioi'tion of the cast 

 the impression of this attachment is to be seen. Its anterior boundary commences 

 at a point on the edge of the impressed zone about 14 mm. in advance of the 

 most anterior portion of the sutiire-line, /. e. the main or inner branch of the siphonal 

 saddle ; it passes outward and backward for a length of about 5 mm., then for a short 

 distance runs nearly parallel to, and at about 5 mm. from, the suture. After passing 

 backward for a distance of nearly 10 mm. from its commencement, the line divides 

 into two principal portions, one being continued almost parallel to, and only slightly 

 approaching, the edge of the impressed zone, the other curving towards, and 

 apparently reaching, the same edge at a distance of 11 mm. from its commencement. 

 A fractui-e of the specimen prevents the former of the two lines being traced any 

 further. About 1 mm. anterior to the incised line just described, there is a much fainter 

 depressed line which, after extending backward for about 5 mm., nearly parallel to the 

 incised line already described, appears to turn outward towards the periphery, and then 

 quickly to disappear, vrhile posterior to the line already described, and also parallel to it, 

 there are two or three much fainter lines. On the other side of the whorl there 

 are lines corresponding to the principal incised line, and the line about 1 mm. anterior 

 to it, but these can only be traced backward sonie G mm., owing to the crushed state of 

 this side of the specimen. 



Near the base of the body-chamber, and slightly on the right side of the median line 

 of the periphery, there is a horseshoe-shaped incised line having its convexity directed 

 forward. Its anterior portion is 12 mm. in advance of the anterior portion of the outer 

 branch of the siphonal (or peripheral) saddle. It is about 6 mm. long, 5 mm. wide in 

 the anterior part, and 3"5 mm. wide in the posterior part. Each limb appears to be 

 continued backward as far as the posterior end of the specimen, which is at about 

 the level of the anterior portion of the outer branch of the peripheral (or siphonal) 

 saddle, as a somewhat irregular, shallow, very faintly-impressed groove or grooves, each 

 being almost parallel to the central line of the periphery. The posterior termination 



14* 



