1754 THE VOYAGE OF H.M.S. CHALLENGEE. 



of equal length, each with ten to twelve alternate-cruciate pairs of lateral branches. Tenninal 

 coronets umbrella-shaped, composed of eight equal, simply forked branches. 



Dimensions. — Length of the shell 3'6, breadth 3*4. 



Hahitat. — South Pacific, Station 293, depth 2025 fathoms. 



Genus 735. Ccelospathis,^ n. gen. 



Definition. — Coelogr aphida with an odd sagittal frenulum on each galea and 

 an outer lattice-mantle, armed with eight styles (two odd and two paii-ed styles on each 

 valve). 



The genus Coelosjyathis differs from the preceding Ccelographis in the possession of 

 four coronal styles on each valve. Two of these are odd and lie in the sagittal plane, 

 viz., the constant vertical nasal style (directed towards the mouth), and the horizontal 

 sagittal style, which is placed in the equatorial plane, in the sagittal axis of the body. 

 The two other styles are paired and identical with the tergal styles of Ccelographis, 

 directed backwards, and divergent to right and left. 



1. CcelospatMs ancorata, n. sp. (PL 128, figs. 1-7). 



Shell-mantle one and a half times as long as broad, its frontal perimeter isosceles triangular ; 

 its zonal perimeter square, its sagittal perimeter nearly rectangular, with a concave excision on the 

 oral side (fig. 1). Odd nasal styles of both valves divergent in the sagittal plane (each with fourteen 

 to sixteen pairs of branches), three times as long as the odd sagittal styles (each with three or four 

 pairs) and twice as long as the paired tergal styles (each with four to six pairs of branches). 

 Terminal coronets (on the free distal end of the styles) three times forked, each with eight slender, 

 widely divergent fingers, which are curved, zig-zag, and armed with alternating recurved hooks ; 

 at the end of each finger a verticU of four to six small recurved teeth (fig. 5). 



Dimensions. — Length of the shell 2 to 3, breadth 1'2 to 21. 



Hahitat. — South Pacific, Station 289, depth 2550 fathoms. 



2. CcelospatMs octostyla, n. sp. (PI. 128, fig. 8). 



Shell-mantle one and a third times as long as broad, very similar to the preceding species ; but 

 differing from this in the following characters : the odd nasal styles bear ten to twelve pairs of 

 branches, and are twice as long as the odd sagittal and the paired pectoral styles, which are nearly 

 equal in size (each with five or six pairs of branches). The eight fingers of the terminal coronets are 

 less divergent and curved than in the preceding species, and each finger bears at its end a verticil 

 of four to six divergent, slender teeth, which are not recurved (fig. 8). 



Dimemions. — Length of the shell 2-2 to 2-6, breadth 1-7 to 19. 



Habitat. — Central Pacific, Stations 27l to 274, depth 2350 to 2750 fathoms. 



' Cteiospai/!.M = Hollow whorl; xsJxoj, o-u-afJ/j. 



