202 bulletin: museum of comparative zoology. 



The midbody is laterally compressed, triangular in lateral view with the 

 anterior margins subequal and both concave. The postmargin is but slightly 

 convex. The anterior process is long, its length equalling that of an anterior 

 margin. The cytopharyngeal margin is expanded ventrally to twice the dorso- 

 ventral diameter of the neck, which is slender, its length being nearly one and 

 one half times that of the process. It is curved dorsally in a regular arc, which 

 continues the curvature of the dorso-ventral margin of the midbody. The 

 head is flattened and the transverse furrow is slightly constricted. 



The antapicals arise from the postero-lateral angle of the midbody and spread 

 latero-posteriorly in a broad curve. The tips are somewhat incurved, but 

 there is no sigmoid flexure as in T. fatula. The greatest distance between 

 the antapicals is 0.63, and that between the tips 0.5 (of the total length). 

 The antapicals are trimcate in dorsal or ventral view, with short lateral 

 terminal spinules. In lateral view they are somewhat rounded. Both 

 horns are deflected to the left distaUy, the dorsal somewhat more than the 

 ventral. 



The lists are heavily and sparingly ribbed and the thecal wall shows no 

 structural differentiation. 



Length to postmargin of midbody, 125 ;x; to tip of ventral antapical, 275 /*. 



Stations, 4385, 4711. 



Its long process and horn are evidently adaptive to the higher temperatures 

 of its habitat. 



Triposolenia fatula, sp. nov. 



Plate 17, Fig. 103. 



A large species resembling T. ambulatrix with less asymmetry of the spreading 

 antapicals and a constricted region in the anterior part of the neck. 



The midbody is low triangular in lateral view with nearly straight margins, 

 the posterior longer, and the antero-ventral shorter than the antero-dorsal. 

 The anterior process is long, its length exceeding the altitude of the midbody. 

 The neck is very long and slender and its distal fifth is reduced in dorso-ventral 

 diameter and bent dorsally to a slight extent. Its length is about 0.2 of the 

 total length. The head is spheroidal and relatively small. 



The antapicals are very long, their length being 4.5 times the altitude of the 

 midbody. They are slightly asymmetrical, the dorsal is slender, does not con- 

 verge or show a sigmoid flexure distally, as does the ventral. The distance 

 between the tips is five times the altitude of the midbody. Distally the dorsal 

 antapical bends to the left, and the ventral one only slightly at the very end. 

 The tips are truncate and mini;tely spinulate. 



The thecal wall is hyaline, structureless, and the collars and lists are heavily 

 but sparingly ribbed. 



Length to postmargin of midbody, 90 /x ; to tip of ventral antapical, 190 fx. 



Station, 4587. 



