106 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Nucleolites marmini Desmoulins. He distinctly says that "perhaps" guadeloup- 

 ensis is congeneric. The two Recent species of Rhyncholampas differ from N. 

 marmini in such essential particulars that I cannot consider them congeneric 

 therewith. Hence it is necessary to restore Mr. Agassiz's generic name. 



Nothing has hitherto been known in regard to the pedicellariae of the 

 genus. They are not abundant and seem to be wholly wanting on the oral 

 surface. Both tridentate and ophicephalous occur; the former are peculiar 

 and might perhaps be considered as rostrate or as a simple form of globif erous ; 

 the ophicephalous closely resemble those of certain clypeastroids, notably Echino- 

 discus. The miliary spines are very peculiar in having successive swellings 

 near tip; there may be two, three, or four of these enlargements (PI. 144, 

 fig. 1). There seem to be no calcareous particles in the tube-feet. 



Key to the Species of Rhyncholampas. 



Unicolor; median actinal area deeply pitted and sculptured cariboearum. 



Spotted; median actinal area with shallow pits and little or no sculpturing . . . pacifica. 



Rhyncholampas cariboearum. 



Cassidulus cariboearum Lamarck, 1801. Syst. Anim. sans Vert., p. 349. 

 Rhyncholampas caribbaearum A. Agassiz, 1869. Bull. M. C. Z., 1, p. 270. 



Plate 144, figs. 6, 7. 



Both tridentate and ophicephalous pedicellariae are found but they occur 

 only sparingly. The tridentate (rostrate?) have the valves rather delicate, 

 from .16 to .48 mm. in length, the width of the base about half the length of 

 the valve. These pedicellariae have considerable mesh-work at the back of 

 the valves, with indications of a chamber similar to that in many globiferous 

 pedicellariae, but there is no evidence of poison-glands. The tip of the blade 

 (PL 144, fig. 7) is provided with long sharp teeth, longest at the middle of the 

 margin, in contrast to the condition in R. pacifica. The base of the valve has a 

 low loop as in ophicephalous pedicellariae. Except for their less robust appear- 

 ance, these tridentate pedicellariae differ little from those of R. pacifica. The 

 ophicephalous pedicellariae have valves (PL 144, fig. 6) only about .10 nun. long, 

 though the loop adds from .03 to .08 more; they are quite similar to those of 

 Echinodiscus tenuissimus. The miliary spines are not essentially different from 

 those of R. pacifica. 



