548 THE VOYAGE OF H.M.S. CHALLENGER. 



or four robust, short, slightly tapering spiuelets ; the outermost is much smaller than the 

 others, and sometimes an additional one is present there. On some of the plates near the 

 mouth one of the spines in the transverse series may be out of the line, which produces the 

 appearance of an oblique pair. At the apex of the plate is a single minute spiuelet placed 

 very high up in the furrow. 



The madreporiform body, which is well defined, circular, and slightly raised, is situated 

 rather nearer the centre than midway between that point and the margin. Its surface is 

 marked with few striations, which are coarse and radiate from the centre to the periphery. 

 There are a few isolated spinelets or granules on the dissepiments. 



Colour in alcohol, a bleached yellowish white. 



Localities. — Off Inaccessible Island, Tristan da Cunha group. Depth 90 fathoms. 



Off Nightingale Island, Tristan da Cunha group. Depth 100 to 150 fathoms. 



Station 148. Off the Crozet Islands. January 3, 1874. Lat. 46° 47' 0" S., long. 

 51° 37' 0" E. Depth 210 fathoms. Hard ground, gravel, shells. Surface temperature 

 41°-0 Fahr. 



Station 145a. Off Prince Edward Island. December 27, 1873. Lat. 46° 41' 0" S., 

 long. 38° 10' 0" E. Depth 310 fathoms. Volcanic sand. Surface temperature 41°-5 

 Fabr. 



Off Marion Island. Depth 50 fathoms. 



Remarks. — This species is characterised by the extreme simplicity of the spinulation of 

 the abactinal plates, and of the armature of the adambulacral plates, and by the lineal dis- 

 position of the granules on the lateral wall of the rays. 



6a. Cribrella simplex, var. granulosa, nov. 



There is a small Cribrella from the neighbourhood of Kerguelen which I consider to be 

 a variety of this species, although at first sight it differs greatly in superficial character. 

 This difference in appearance arises from the fact that the granules on the abactinal plates 

 are larger and more numerous, and that the lineal disposition of granules on the lateral 

 wall of the ray is more or less masked. The variation rnay_be traced through various 

 stages of divergence from the type form, and in some the only differences noticeable 

 are the larger size and somewhat greater number of the granules. On these grounds 

 I do not consider that there is sufficient justification for regarding the Kerguelen form as 

 specifically distinct from Cribrella simplex. The mimetic resemblance of this variety to 

 Pedicellaster scaber from the same region is highly remarkable. 



Colour in alcohol, a brownish ashy grey. 



Localities. — Eo) T al Sound, Kerguelen Island. Depth 28 fathoms. 



Off Kerguelen. Position not recorded. Depth 10 to 50 fathoms. 



