HOLOTHURIOIDEA, ASTEROIDEA, AND ECHINOIDEA 39 1 



head. Fig. 6 gives a representation of a valve of such a large form. These 

 valves are found mainly in the oral region, a few also inside the subanal 

 fascicle. They are very short-stalked, but have an exceedingly long neck — 

 up to 7 mm. long, when fully extended — a feature rather unique in Echinoids. 

 One of these large pedicellariae had four valves. Ophicephalous pedicellariae 

 were not found by Clark. I have observed a few of them in the smaller 

 specimen. They are of the typical Spatangoid shape (fig. 7). The triphyllous 

 pedicellariae were figured by ClarK, but his figure not being very distinct, a 

 new one is given here (fig, 8). Numerous slender, irregular, calcareous rods 

 are found in the tubefeet, in marked contradistinction to the other species, 

 N. depressus H. L, Clark, in which the tubefeet are stated to be entirely 

 devoid of calcareous particles (H. L. Clark, Op. cit. p. 150). 



The genital organs of the larger specimen were found to be quite empty, 

 thus giving no information of the character of the eggs. Judging from the 

 large size of the genital pores, it may, however, be fairly safely concluded 

 that the eggs are large and yolky, and the development direct. 



The species is as yet only known from Juan Fernandez, where it was 

 found by the »Hassler» Expedition in a depth of 65 fms. It was not refound 

 till now. 



It would appear that the genus Nacospatangus is nearly related to Goni- 

 maretia, the only essential difference being found in the structure of the globi- 

 ferous pedicellariae. Their being referred to two different families, Nacospa- 

 tangus to the Palaeopneustidae, Gonimaretia to the Spatangidae, as done by 

 H. L. Clark, therefore does not give a true statement of their natural rela- 

 tionship. Also Clark himself agrees (Op. cit. p. 149) that the position of the 

 genus Nacospatangus is more naturally within the Spatangidce. 



