Boone, Moilusca, Cruises of "Eagle" and "Am," 1921-28 181 



Technical description: The " Ara" specimen is somewhat larger 

 than the type, measuring 130 mm. total length. The body is 90 mm. 

 long, moderately slender, cylindrical anteriorly for some two-thirds 

 of its length; posteriorly tapered conically. The anterior mantle 

 margin is produced to a rounded triangulate median dorsal angle, 

 and has a moderate median ventral concavity accentuated by distinct 

 triangular points, one on each side of the siphon. The fins are stout, 

 a little more than one-third of the total body length, slightly incised 

 at the anterior point of attachment and with the lateral margin mod- 

 erately rounded, the pair forming a wide heart-shaped contour which 

 is widest anteriorly. The posterior angle of the fins of the present 

 specimen is bluntly rounded and projects beyond the tip of the body 

 a trifle, in this respect differing from Hoyle's type, a younger 

 specimen. 



The head is that of a typical Loligo, wider than long, flattish dorso- 

 ventrally, with the optical region large ; a deep ventral groove beneath 

 the siphon. 



The arms are of unequal length, decreasing in length in the order 

 4, 3, 2, 1; the first pair are slender, with a definite dorsal keel; the 

 second pair have a distinct ventrolateral keel ; the third pair are wide 

 and flattened with a distinct web externally; the fourth pair are 

 about as stout as the third and laterally have a groove-like excavation, 

 especially the side towards the tentacle. The suckers are of the usual 

 type, the horny ring set with a series of blunt squarish teeth, sepa- 

 rated by distinct notches; there are about twelve smallish teeth on 

 the proximal side of the ring and eight or nine larger ones on the 

 upper side. The tentacular arms are small, slender, distinctly three- 

 sided up to the club ; the club is about one-third of the total length, 

 typically Loligo, with a web on each side and a separate small, ventral 

 web on the distal half, widening distally; the club is set with about 

 six or eight proximal suckers, followed by a double median row con- 

 sisting of about eight to ten large suckers, each about twice the diam- 

 eter of the adjacent lateral ones and succeeding these suckers are 

 four rows of closely crowded distally diminishing small suckers. The 

 horny ring of a typically large tentacular sucker has five broad blunt 

 square-cut teeth on the upper side and eight or nine acute teeth 

 separated by spaces slightly wider than themselves on the proximal 

 side. The buccal membrane has seven points, each with one or two 

 very minute suckers. The beak and pen have not been extracted, as 

 this is the only specimen on hand. 



