124 
THE VOYAGE OF H.M.S. CHALLENGER . 
former 70 mm. long, the latter 163 mm. long. Body cylindrical or elongate, 
oval, nearly equally rounded at each extremity, neither quadrangular nor penta- 
gonal, possibly slightly flattened on the sides and on the back. The closed 
mouth and the anus slightly bent upwards, the former surrounded by five 
not very large ridges, the latter with five distinct teeth. Five to six pedicels are 
placed side by side in each of the three ventral ambulacra, excepting towards 
the extremities of the body, where they decrease in number, and papillae become 
substituted for them. The dorsal papillae, more thinly scattered all over the 
back, are situated on the tops of low protuberances, those, in the neighbourhood of 
the two dorsal ambulacra being slightly larger and more closely placed. Along 
the sides of the body, exteriorly to and above the lateral ventral ambulacra, 
there is a rather broad almost naked space. The thick perisome is filled with 
crowded deposits of several different kinds — large, irregularly rounded, thick, not 
overlapping scales ; numerous crowded, delicately constructed reticulate spheres ; 
scattered larger and more solid spheres, which seem to be transformed into 
scales ; and numerous more or less irregularly formed, reticulate cups with spines 
round the uneven rim, these cups being present in the exterior layer of the 
perisome. 
The following species of Colochirus are unsatisfactorily known, and require to be 
re-examined : — 
Colochirus viridis, Semper, 1868. 
Body cylindrical, flattened below. Dorsal ambulacra with two rows of conical papillae. 
The odd ambulacrum with two rows of pedicels ; the lateral ventral ambulacra 
with an inner simple row of pedicels and an exterior row made up of papillae. 
Habitat . — Samboanga (Semper). 
Deposits unknown. According to the figure, drawn by Semper, the dorsal papillae 
seem to be slightly irregular in position. 
Colochirus colloradiatus, Haacke, 1880, 
Pedicels sparingly distributed, for min g one or two rows on each of the three ventral 
ambulacra. Papillae very scattered, placed in a simple row along each of the 
two dorsal ambulacra. Deposits — scales in the dorsal perisome ; two kinds of 
regularly formed bodies ; and also irregularly formed bodies in different portions 
of the body. 
Habitat . — Mauritius (Haacke). 
Colochirus propinquus, Haacke, 1880. 
Nearly allied to the preceding form, but distinct from it by the absence of regularly 
formed buttons. 
Habitat . — Mauritius (Haacke). 
