212 A. K Verrlll — North Americmi Cephalopods. 



a roughened or slightly corrugated and decidedly excavated area 

 between it and the cutting edges ; the cutting edge below this ridge 

 is nearly straight, or slightly convex ; the notch at its base is 

 rounded and deep and strongly excavated at bottom ; the tooth is 

 broad, stout, obtusely rounded at summit, sloping abruptly on the 

 side of the notch, and gradually to the alar edge. The anterior edge 

 of the aliB, beyond the tooth, is rounded and strongly striated ob- 

 liquely; it makes, with the cutting edge, an angle of about 110°. 

 The innner surfaces of the two sides of the internal plate of the 

 rostrum form an angle of about 45°, 



The lower jaw of No. 1 (Plate XVIII, fig. 3) is represented only 

 by its anterior part, the alae and gular laminre having been cut away 

 by the person who removed it.* It agrees very well in form and color 

 with the corresponding parts of the oue just described, but is some- 

 what smaller. The lateral ridges of the rostrum are rather more 

 prominent, and the area within it is narrower and more deeply exca- 

 vated, especially at the base of the notch, Avhere the excavation goes 

 considerably lower than the inner margin. The notch is narrower 

 and not so much rounded at its bottom. The tooth is about the same 

 in size as that of No. 10, and appears to be even more prominent, 

 because the anterior edge of the aloe is more concave at its outer 

 base ; it is also more compressed and less regularly rounded at sum- 

 mit. This jaw measiires 32*5'"'" (rSO inches) from the tip to the pos- 

 terior ventral border of mentum ; 17™'" from the tip to the bottom 

 of the notch; 4™'" from bottom of notch to tip of the tooth. 



Both these lower jaws agree in having a very prominent tooth on 

 the alar edge, with a large and deeply excavated notch between it 

 and the cutting edge of the beak, and in this respect differ from the 

 lower jaw of A. Harveyi^ for in the latter the tooth or lobe is broad 

 and less prominent, while the notch is narrower and shallower. 

 This seems to be the best character for distinguishing the jaws of 

 the two species. But they also differ in the angle between the alar 

 edge and the cutting edge of the rostrum, especially of the lower 

 jaw, for while in A. Harveyi this is hardly more than a right angle, 

 in A. princeps it is about 110°. Moreover, the darker color and 

 firmer texture of the jaws of the latter seem to be characteristic. 



To this species I have referred the Catalina specimen (No. 14, 

 p. 189), preserved in the New York Aquarium. The jaws of the latter, 

 which were examined and carefully measured by me, agree very 



* The specimen was given to the Smithsonian Institution by Mr. G. P. Whitman, 

 of Rockport, Mass., in 1872. (No. 2524). 



