256 DOHOCIDARIS PAPILLATA. 



Anal system pentagonal, with a more or less pointed plate extending be- 

 tween the genital plates to ocular plates, genital plates rectangular with 

 truncated edges, genital opening large, placed one third diameter of plate 

 from outer edge, ocular plates heart-shaped, ocular opening distinct. Ain- 

 bulacral papillae long, slender; interambulacral much curved and stouter. 



In younger specimens the sutures are not so prominent, the stellar shape 

 of the anal system not so marked* 



There are considerable differences in the external appearance of specimens 

 collected at different points. A lot of specimens dredged off Carysfort Reef, 

 at a depth of sixty fathoms, at first sight presents such striking contrast to the 

 bulk of the specimens, that it was catalogued as a distinct species. Instead 

 of the long smooth spines, perfectly white, which was characteristic of all 

 the specimens (except quite small ones) thus far collected, they have long 

 slender spines, not so stout in proportion to the diameter of test as when 

 ridges are worn out, with very distinct and prominent longitudinal rows of 

 serrations, but the base of the spine and the milled ring have the same 

 character as the other spines. There is, however, round the abactinal sys- 

 tem a circle of younger spines, which are not serrated, but are, on the con- 

 trary, somewhat stouter than others, short and smooth, having the same 

 structure as the spines of specimens where all are smooth, or nearly so. The 

 specimens with these slender primary spines also have secondary spines 

 round the primary tubercles of much greater fineness. The coronal plates 

 arc more numerous in the specimens with liner serrated spines, but not 

 more so than we find in many of the younger specimens, where the spines 

 are smooth. Had it not been for some specimens collected in forty fathoms 

 near Carysfort Reef, I should have considered these dill'erences of sufficient 

 value to be specific ; but several fine specimens possessing half-striated, half- 



* The measurements are given in millimetres, the abactinal system is measured from the extremity of 

 the genital plate earrying inadreporic body to the outer edge 'of the opposite oeular plate The aetinal sys- 

 tem is measured from the median interambulacral line to the opposite median ambulaeral space. The 

 length of the anal system and of the spines when given is always the greatest length. The number of 

 coronal plates given is the number of the interambulacral plates carrying the primary tubercles. 



From forty to two hundred and seventy fathoms. 



