Boone, Molltisca, Cruises of "Ara" and "Alva" 333 



Vanderbilt Marine Museum, at Northport, N. Y., are the only 

 specimens of this species known to be in any American museum. 



Technical description : The largest of the Cebu specimens 

 is fully matured, has a total body length of 100 millimeters. The 

 body is obconical, of about 25 millimeters diameter anteriorly and 

 very tapered posteriorly to a blunted apex. The free mantle mar- 

 gin is produced anteriorly to a distinct rounded triangular process 

 in the median dorsal line from which it slopes to the lateral mar- 

 gin; ventrally this margin is shallowly widely concave beneath 

 the siphon and produced to a blunt triangular point on either side. 

 The caudal fins are each triangular, with the outer angle rounded, 

 the anterior lateral margin only three-fourths as long as the post- 

 lateral margin, the paired fins outlining a rhombic figure. In 

 adults the length of the fin is slightly more than one-half the total 

 body length, those of the present specimen being 55 millimeters 

 long on a body 100 millimeters long. In younger specimens the 

 fins are much shorter in ratio to the body length, those of the very 

 young being not quite one-third of the total body length, with the 

 margins rounded, somewhat heart-shaped; those slightly larger 

 have the posterior portion of the fins more attenuate, subacu- 

 minate. 



The exposed portion of the siphon is short, distally bluntly 

 rounded, with a moderately broad aperture, divided by an inner 

 transverse septum. 



The head is wider than long, dorsoventrally compressed, 

 rounded ; the eyes are large, lateral. 



The sessile arms decrease in length in the order 3, 4, 2, 1, with 

 the first and second pairs of arms each dorsally webbed on the 

 outer side ; the third pair are similarly webbed but for a shorter 

 space, while the fourth pair are webbed along the upper lateral 

 margin. The suckers of the sessile arms are moderately large, 

 pedunculate, set obliquely, in two rows approximately, with the 

 lateral margin on either side produced into a thin, ribbon-like 

 webbing. The suckers of the third pair of arms are eighteen per 

 row and are distally larger than those of the other pairs of arms. 

 The horny ring of one of these large suckers has eight sharp, 

 close-set, triangular teeth on the distal side, the proximal half of 

 the ring being smooth. 



The outer buccal membrane is produced into five distinct 

 points, one attached between the first pair of arms, one each to 



