866 THE VOYAGE OF H.M.S. CHALLENGEE. 



Genus 374. Coleaspis, 1 Haeckel, 1881, Prodromus, p. 468. 



Definition. B elonaspida with forty parmal pores (two on each plate), with 

 numerous by-spines and with a network of prominent crests on the dimpled surface. 



The genus Coleaspis differs from its ancestral genus Dictyaspis in the development 

 of numerous by -spines, and bears therefore among the ellipsoidal Belonaspida the same 

 relation to it as Hystrichaspis does to Coscinaspis among the spherical Dorataspida. 

 If the four equatorial spines in Coleaspis become different in pairs, it passes over into 

 Hexalaspis. The shell is usually very dark and thick -walled. 



1. Coleaspis coronata, n. sp. 



All twenty spines of nearly equal size and form, about as long as the radius of the shell, com- 

 pressed, sword-like, two-edged ; both equatorial spines of the hydrotomical axis little longer than 

 the eighteen others. Crests between the dimples of the shell-surface dentated, forming around the 

 basal half of each spine a cylindrical sheath with a dentated, crown-like mouth, the teeth of which 

 are prolonged into simple by-spines. (Similar to Hcxaconus coronatus, PI. 139, fig. 5, but differing in 

 the nearly equal size of the spines and their sheaths, and in the longer by-spines.) 



Dimensions. Major axis of the shell 0'2, minor 017; length of the spines 012, basal breadth 

 0-02. 



Habitat. Central Pacific, Station 266, surface. 



2. Coleaspis vaginata, n. sp. (PL 140, fig. 13). 



All twenty spines of nearly equal size and form, nearly as long as the diameter of the shell, 

 conical ; both equatorial spines of the hydrotomical axis about one-third longer than the eighteen 

 others. Crests between the dimples of the shell-surface serrated, forming around the basal half 

 of each spine a conical truncate sheath with crested surface and serrated mouth, the teeth of which 

 are prolonged into short by-spines. (Similar to Hexaconus vaginatus, PI. 139, fig. 7, but differing in 

 the nearly equal size of all the spines and in the double thickness of the shell-wall.) 



Dimensions. Major axis of the shell 012, minor 01 ; length of the spines 0'08, basal 

 breadth O'Ol. 



Habited. North Pacific, Station 253, surface. 



3. Coleaspis obscura, n. sp. 



All twenty spines of nearly equal size and form, little longer than their large cylindrical sheaths, 

 which are nearly as long as the radius of the shell, and armed on the truncated mouth with strong 

 triangular by-spines, both equatorial spines of the hydrotomical axis one and a half times as long as 

 the eighteen others. Shell very dark and thick walled, quite opaque. 



1 Coleaspis = Shield with sheaths ; 



