178 HAWAIIAN AND OTHER PACIFIC ECHINI. 



purpose of comparison with allied forms. The Albatross series consists of speci- 

 mens from 32 to 62 mm. in length. 



Station 2769. Off Cape Dos Bahios, Argentina. Bott. temp. 56.6°. 

 51.5 fms. Gn. m., fne. s. 



Station 2771. Near Port Gallegos, Argentina. Bott. temp. 49.4°. 50.5 

 fms. Gy. s., bl. sp. 



Station 2778. Straits of Magellan. Bott. temp. 47.9°. 61 fms. Gy. s., 

 bl. sp. 



Station 2779. Straits of Magellan. Bott. temp. 46.9°. 77.5 fms. Gn. oz. 



Bathymetrical range, 50.5-77.5 fms. Extremes of temperature, 56.6°- 

 46.9°. 



Nine specimens. 



Brisaster. 



Gray, 1855. Cat. Rec. Ech. Brit. Mus., p. 61. 

 Type, Brissus fragilis Duben and Koren, 1846. Skan. Ech., p. 280. 



This group seems quite entitled to recognition and I do not hesitate to give 

 it full generic rank. The species, however, are not sharply defined and I find 

 it difficult and occasionally impossible to distinguish all the forms that have 

 been named. Both Mortensen and Doderlein consider Studer's species capensis 

 as at least a recognizable variety of fragilis but in this I cannot follow them. 

 I am unable to find any good reason for using Studer's name and am obliged 

 further to maintain that Doderlein's species antarcticus cannot be recognized. 

 On the other hand, the form which in the Challenger Report is called ventri- 

 cosus is probably identical with latifrons, the true ventricosus Gray being the same 

 as Schizaster lacunosus (L.). Mortensen first pointed this out in his full dis- 

 cussion of the genus Schizaster (1907, Ingolf Ech., pt. 2). On the other hand. 

 one of the Challenger specimens from Kerguelen, labeled tnosehyi, has led 

 to the conclusion that two species are confused under that name, and I have 

 accordingly given the name kerguelenensis to the island form. 



Key to the Species of Brisaster. 



Lateroanal fasciole complete, rarely broken on one side, very rarely on both. 



Ambulacrum 111 moderately wide, the width of petal III at its anterior end about 



J its length or less; the other petals rather narrow and not truncate at tip . . fragilis. 

 Ambulacrum III wide, the width of petal III at its anterior end about \ its length; 



the other petals broad, truncate at tip by the very wide poripotalous fasciole . indicut. 



