276 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Station 2787. Off Taytao Peninsula, Chile; 46 47' 30" S., 75 15' W. 

 Bott. temp. 53.9. 61 fathoms. Gn. m. 



Bathymetrical range, 19.75449 fathoms. Extremes of temperature, 53.9- 

 46.9. 



One hundred and thirty-one specimens. 



NUDECHINUS, gen. nov. 



Type-species, Nudechinus scotiopremnus, sp. nov. 



The group of species to which the name of Nudechinus is given is probably the 

 least known of any similar group of Echinidse. They are small species having in 

 common the two characters of a thin, bare bucoal membrane and Lytechinus-like 

 globiferous pedicellariaj. That they form the connecting link between Lytechi- 

 nus and Gymnechinus seems unquestionable, but I cannot follow Mortensen 

 in putting them in the latter genus. The highly specialized abactinal system 

 of Gymnechinus is of far greater value for limiting a natural genus than any 

 character shown by buccal membrane or pedicellariae. Not having seen speci- 

 mens of darnleyensis Woods, inconspicuous Mortensen, or Gravieri Koshler, I 

 have selected for the type of the genus the larger of the two new species herein 

 described, though its status is not any more satisfactorily settled than that of the 

 other species. We have placed multicolor Yoshiwara in this genus after examin- 

 ing the type-specimen, which was most courteously loaned by Professor Goto of 

 the Imperial University, Tokyo. The specimen (PI. Ill, figs. 7-5) is 14 mm. in 

 diameter and 8 mm. high. The actinostome is large, 7 mm. across, while the 

 abactinal system is very small, 3 mm. in diameter. There are 14 or 15 inter- 

 ambulacral and 17 or 18 ambulacral plates in each column. The buccal mem- 

 brane is thin and except for the ten small, well-separated buccal plates, is per- 

 fectly bare. Oculars I and V reach the periproct. The globiferous pedicell arise 

 have valves about .35 mm. long, with a very conspicuous, straight terminal tooth, 

 .15 or .16 mm. in length. The ophicephalous pedicellarise are abundant and not 

 peculiar. No tridentate could be found, though prolonged search was made. 

 The coloration is slightly different from Yoshiwara's description, for we find no 

 brown markings on the test; all such markings seem to be deep green. The 

 spines are essentially as described by Yoshiwara, the violet bands being very 

 distinct though not sharply defined. Kcehler's species Gravieri is very 

 near multicolor but if the color of the spine-bands in the former is really "clear 

 rose," the general appearance must be very different from multicolor. It seems 



