292 



bulletin: museum of comparative zoology. 



face, 1 girdle width wide on ventral and 2 to 3 on dorsal face. Low fins with 

 spinules at nodes are found on the straight ribs at the sides of the ladder. 

 Girdle fins spinulate, girdle ribbed. Ventral fins scarcely elevated above 

 general sagittal fin. 



Length, 69 /z; dorso-ventral diameter, 36 n) transverse, 43 p. 



Sta. 4681. 



DlNOPHYSIS COLLARIS, Sp. nOV. 



A small species of squarish outline and thin body. Length, excluding 

 spines, 1.05 greatest dorso-ventral diameter. Epitheca very wide dorso- 

 ventrally, 0.8 of dorso-ventral diameter of body, apex concave. Ventral 

 outline convex, posterior and dorsal broadly rounded, the latter concave 

 just posterior to girdle. Anterior and posterior collars approaching hori- 

 zontal position, abundantly (18 on side) ribbed. Ventral, posterior, and dorsal 

 fins connected in complete sagittal fin; dorsal low, with spinules, posterior 

 carried out in two stout spine-like projections with reticulate skeleton, their 

 length about 0.25 of dorso-ventral diameter; the ventral with skeleton of 

 numerous anastomosing ribs, its greatest width posterior, about 0.4 dorso- 

 ventral diameter. Transverse diameter about 0.35 the dorso-ventral. Sur- 

 face uniformly covered with small, irregular polygons of heavy mesh. 



Somewhat resembles D. triacantha with duplicated antapical spine. 



Length, excluding spines, 58 fx; dorso-ventral diameter, 55 /*. 



Sta. 4671. 



Dixophysis expulsa, sp. nov. 



A small species, in lateral view with broadly rounded, sac-like outline, 

 widening posteriorly, with marked lateral constrictions behind girdle. Length 

 1.14 times greatest dorso-ventral diameter. Epitheca low, convex anteriorly, 

 its dorso-ventral width 0.57 of dorso-ventral diameter of body. About 0.35 

 of the length from the apex the sides of the epitheca are impressed by a trough- 

 like constriction which decreases the transverse diameter at that level over 

 ten per cent. Immediately behind this region the bulging sides attain a 

 transdiameter equalling or even exceeding that just behind the posterior 

 collar, as shown clearly in dorsal or ventral view. Collars without ribs, low, 

 at 45°, anterior one 0.78 diameter of posterior. Ventral fin simple, 0.14 of 

 length of body in width, its length 0.66 that of body, without ribs other than 

 the double fission rib. Surface centrally faintly reticulate, with scattered 

 pores centrally located in some of the meshes. 



Length, 55 /j.; dorso-ventral diameter, 48 ix. 



Sta. 4717. 





