[43] CEPHALOPODS OF NORTHEASTERN COAST OF AMERICA. 
area within it is narrower and more deeply excavated, especially at the 
base of the notch, Where 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 
ala is more concave at its outer base; it is also more compressed and 
less regularly rounded atsummit. This jaw measures 32.5"".(1.30 inches) 
from the tip to the posterior ventral border of mentum; 17" from the 
tip to the bottom of the notch; 4°" from bottom of notch to the 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 promi- 
nent, 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. Harvey? this is 
hardly more than a right angle, in A. princeps it is about 110°. More- 
over, 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. 13), 
preserved in the New York Aquarium. The jaws of the latter, which 
were examined and carefully measured by me, agree very closely, both 
in form and size, with those of No. 10, the type of the species, but are a 
trifle larger. The total length of the upper mandible is 133"; greatest 
breadth, 99°"; from inner angle of anterior edge to the dorsal end of 
frontal lamina, 95"; tip of rostrum, or beak, to the dorsal end of frontal 
lamina, 92""; tip of rostrum to bottom of notch, 19°"; notch to inner end 
of anterior edge, 38""; transverse breadth between anterior edges, 17"". 
The total length of the lower mandible is 95""; breadth from gular 
lamina to inner end of ala, 99°"; front edge of jaw to posterior end of 
gular lamina, 83""; breadth of ale, 41""; posterior edge of al to end 
of gular lamina, 44.5""; tip of beak to bottom of notch, 22"; notch to 
inner angle of ale, 70°"; depth of notch, 3.5". 
The general form of this species is very well shown on Plate VIII. 
This figure has been made from the sketches. and measurements made 
by me soon after the specimen was received in New York and before it 
had been “‘mounted” (see p. 13). The head was, however, so badly in- 
jured that it could not be accurately figured, and this part is, therefore, 
to be regarded as a restoration, as nearly correct as could be made under 
the circumstances. It may require considerable corrections, both as to 
size and form. The caudal fin is remarkable for its small size, as in A. 
Harveyi. Its breadth is scarcely more than that of the greatest diameter 
of the body. It is short-sagittate in form, with strongly divergent side 
lobes, which extend forward beyond their lateral insertions, and end in 
