(34 • THE VOYAGE OF H.M.S. CHALLENGEK. 



ambulacra! system (PL VI. figs. 8, 14), the absence or smaller number of the more 

 prominent secondaries and miliarias, the proportionally narrower poriferous zone, the 

 indistinctness of the S-shaped bands of the median interambulacral spaces, the slighter, 

 less deej), actinal cuts, and the comparatively smaller size of the genital openings ; these 

 last, as I have shown in the smaller specimens of another species from the West Indies, 

 are perforated quite late. The tentacles of the abactinal part of the test are flattened 

 pouches, pointed at the extremity, resembling those of our common Arhacia piistulosa, and 

 evidently, from their size in alcoholic specimens, capable of as great expansion as those of 

 that species figured in Revision of the Echini, pi. v. figs. 1, 2, 6-8. 



The pedicellarias of Ccelopleurus agree well in the main with those characteristic of 

 the Arbaciadse, consisting of the two types, the short-headed, long-stemmed, globular 

 pedicellaria3 (PI. XLV. figs. 3, 4), so characteristic of the abactinal portion of the test in 

 Podocidaris and Arhacia, and the large-headed ones (PI. XLV. figs. 1, 2) occurring nearer 

 the ambitus. 



Station 201. October 26, 1874. Lat. 7° 3' N., long. 121° 48' E.; 82 fathoms and 

 102 fathoms ; stones and gravel. 



Amboyna; 100 fathoms, Octobers, 1874. 



Station 192. September 26, 1874. Lat. 5° 42' S., long. 132° 25' E. ; 129 fathoms ; 

 mud. 



DlADEMATID^. 



Family Diadematid^, Peters, 1853, Monatsb. Akad. Berlin {emend.). 



Diadema. 

 Diadema, Schynv., 1711, Thes. Imag. (Peters, emend.). 



Diadema setosum. 



Diadema setosa, Gray, 1825, Ann. Phil, (non Rumph). 



St Vincent, Cape Verde Islands. 



Cebu, Philippine Islands. January 1875. 



Papeete Reef. September 1875. 



St Thomas. 



*A spidodiade ma. 



Aspidodiadema, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 199. 



This is a most interesting genus, intermediate between the Cidaridfe proper and the 

 Diadcmatidse. It has like the latter a thin test, with long hollow primary spines nearly 

 straight, and strongly verticillate, especially in the young. The miliary and secondary 

 spines are like the primary radioles, only shorter and proportionally slender (PI. VIII. 



