THE PAMILT ABBACIABJB. 39 



Further adorally, the gecondary tubercles on the outside of the 

 great tubercles are on an oblique and downward-trending part of 

 the plates. Still lower, and on the actinal surface, the want of a 

 transverse direction in the plates is evident, and in some speci- 

 mens the plates are clearly oblique to the median line. 



YI. Recent Ccelopleuri. — Goelopleurus Maillardi, Mich., sp. 



This very beautiful recent species has been found down to the 

 depth of 102 fathoms in the seas to the E. of Africa, of the 

 Philippines, Amboyna, and of the Indian archipelago. 



The species was revised by A. Agassiz in ' The Eevision of the 

 Echini,' 1872-1874 ; and since the appearance of that great work 

 there have been important notices of the species in the Eeport 

 on the Echini of the ' Challenger ' Expedition, 1881, p. 60, by the 

 same author. 



The description of Goelopleurus Maillardi in the ' Eevision ' was 

 not accompanied by a drawing of the test, but in the Report of the 

 ' Challenger ' Echini there are delineations of the test, the spines, 

 the pedicellariae, and the jaws. 



The alliance of the fossil species Coelopleiorus Forlesi, d'Arch., 

 and C. Maillardi, Mich., is very close ; and the dissimilarities relate 

 to increased height of, and the want of obliquity in, the interradial 

 plates, the absence of regular rows of secondaries between the 

 poriferous zones and the large interradial tubercles, and the 

 delicate nature of the ornamentation in the apical system and 

 median interradial line in the recent form. Agassiz mentions 

 the structures in which there is variation in the different speci- 

 mens of the recent species ; and it is interesting to note that, as a 

 rule, the variation does not link the recent and the fossil forms. 

 Agassiz states, op. cit. page 63 : — " The principal differences in 

 smaller specimens consist in the proportionally greater width of 

 the ambulacral areas, the absence or smaller number of the more 

 prominent secondaries and miliaries, the proportionally narrower 

 poriferous zone, the indistinctness of the S-shaped bands of the 

 median interradial spaces, the slighter and less deep cuts, and 

 the comparatively smaller size of the generative openings." 



The recent form is not so tumid as the fossil species, and is 

 comparatively higher, and more rounded and convex above the 

 ambitus ; there is not the conical flattening which is seen in 

 the fossil forms. The small primary tubercles reach up in 



