CEPHALOPODA OP THE CEBTACEODS MARLS. 247 



sidered the inner face of the volution as the dorsal, which is perhaps 

 correct enough in speaking of the animal, but Dr.. Tuomey says the septa 

 shows on the hack a recurved lip, which, if we consider the back the outer 

 surface or edge of the volution, as is usually done, this is entirely wrong 

 for this cast, as the septa extend directly across the back and over to the 

 septal process in an almost straight line. Therefore, if Dr. Tuomey's de- 

 scription is correct for his species, which I have never seen, this one must 

 be an entirely distinct species. I shall at any rate consider it as A. pau- 

 cifex of Cope, and disregard Dr. Tuomey's name until further evidence is 

 obtained. If they prove identical Dr. Tuomey's name has precedence, as 

 it was given in 1854, while Dr. Cope's name dates only from 1866. The 

 present shell may be more fully described as follows: 



Shell large, somewhat ponderous, ventricose, with a broadly rounded 

 back and convex sides; umbilicus slightly impressed, but not open, the 

 inner edge of the lip rather overlapping the one within, and the outer volu- 

 tion embracing the inner to that extent; aperture large, forming half of a 

 long ellipse, being rounded on the outer margin and gradually expanding 

 to the edge of the umbilical depression or for nearly four-fifths of the entire 

 length of the opening. On the inner side it is strongly modified by the 

 projection of the inner volution; entire length of the apertural opening 5 J 

 inches on the specimen; greatest width across nearly 4 inches. Septa 

 strong, deeply concave and distant, being nearly 3 inches apart on the back 

 of the specimen described at the third chamber, and nine chambers only 

 visible to the volution; lateral septal processes situated nearer to the outer 

 margin than to the umbilicus, and are large, strong, slightly directed out- 

 ward from a circular line half as wide across the origin as long, that of the 

 second septum shown on the specimen being 2 inches long from the curve 

 of the inner portion of the septum and IJ inches on the outer side. Inner 

 portion of the septal line moderately arched fprward between the umbilical 

 line and the septal process (or lateral lobe) and reaching slightly in advance 

 of the outer division, which from the base of the process or lobe extends 

 almost directly across the back of the shell ; siphon rather large, measuring 

 more than a quarter of an inch in diameter at the outer chamber, cylindrical 

 as far as can be seen; situated at about one-fifth or a little more than one- 



