168 Bulletin, Yanderlilt Marine Museum, Vol. IV 



This species is most intimately related with I. illecehrosus coindetii 

 (Verany) 1837, "which is known from European waters, according to 

 Pfeffer. 



Material examined : One specimen dredged in 200 fms., 9 miles S. W. 

 by TV. of Port Basque, Newfoundland, September 1, 1926. One specimen, 

 tag 263, taken at Halifax, Nova Scotia, August 3, 1923, by the "Ara." 



Diagnostic characters: For full diagnosis of the anatomy with 

 numerous illustrations and notes on the habits and color of this species 

 consult A. E. Verrill: North American Cephalopods, p. 268, pis. 28, 

 29. figs. 5, 5a, p. 37, fig. 8, and pi. 39 ; Trans. Conn. Acad. Arts and 

 Sci. V., 1880. This masterly diagnosis resulted from the study of an 

 unusually large series of living as well as laboratory specimens of 

 various stages of growth development. 



The larger "Ara" specimen is well grown, with the body dorsal line 

 measuring 245 mm. ; the dorsal arms 130 mm. long from tip to the 

 umbrella margin; the head from umbrella margin to posterior mar- 

 gin measures 45 mm. in the dorsal line, giving the shrunken specimen 

 a total length of 410 mm. in the dorsal line ; the tentacular arm is 235 

 mm. long. The caudal fin is transversely rhomboidal; 110 mm. long 

 from the insertion of fin to tip of tail ; the greatest width 150 mm. 



The body is long and slender in young specimens, stouter in older 

 adults and especially so in gravid females. The caudal fin is trans- 

 versely rhomboidal or very broadly spearhead-shaped, about one-third 

 wider than long, its breadth not quite half the length of the mantle. 

 The exposed portion of the head is large, well rounded, wider than 

 long, its width about equal to that of the adjacent body; its sides in 

 the region of the eyes somewhat swollen ; the ventral surface is flat- 

 tened, with a deep semi-elliptical depression into which the dorsal half 

 of the siphon-tube fits closely. 



Behind the eyes the sides of the head have a conspicuous transverse 

 ridge, which curve back a little, becoming less conspicuous and meet- 

 ing on the dorsal side of the head. Behind these ridges the head 

 abruptly narrows to the neck. There are three thin, erect, lamelliform 

 folds of the skin, extending backward from the transverse ridge, on 

 each side of the head ; the median fold is about in line with the lower 

 eyelid ; the upper fold at its upper end is about midway between the 

 upper fold and the median dorsal line but inwardly curving down- 

 ward to the base of the median fold. The lower fold is a little shorter 

 than the others and curves upward posteriorly to the median one. A 

 small pore is situated within the lower facet. 



