146 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Argopatagus. 



A. Agassiz, 1879. Proc. Amer. Acad., 14, p. 209. 

 Type, Argopatagus vitreus A. Agassiz, 1879. Loc. tit. 



It was with great surprise that I made the discovery that Doderlein's 

 genus Meijerea is identical with Argopatagus, and that the type species, M. 

 humilis (= Phryssocystis humilis de Meijere), and the Hawaiian form to which 

 Mr. Agassiz and I gave the name M. excentrica are both identical with the 

 Challenger species, Argopatagus vitreus. I have never seen any of the Chal- 

 lenger specimens and know nothing of their pedicellariae. The few speci- 

 mens of the genus at hand have pedicellariae like those figured by Doderlein 

 (1906. Valdivia Ech., pi. xlix, fig. 7). The remarkable ophicephalous 

 pedicellariae are highly characteristic and indicate a close relationship with 

 Phryssocystis, the only other genus of Echini with such curious pedicellariae. It 

 is possible that there is only one species of Argopatagus but I cannot believe 

 that the specimen from station 4919 is the same as the others. Accordingly 

 two species, distinguished primarily by the difference in the form of the test 

 are recognized. 



Key to the Species of Argopatagus. 



Test highest at or just back of the middle vitreus. 



Test highest at posterior end where it is abruptly truncate planus. 



Argopatagus vitreus. 



A. Agassiz, 1879. Proc. Amer. Acad., 14, p. 209. 



This species was first collected by the Challenger, which took several 

 specimens in the Arafura Sea at 800 fms. The Siboga took a single specimen 

 in 257 fms. just south of Celebes, but de Meijere, struck by the resemblance to 

 Phryssocystis aculeata, failed to compare it with Argopatagus and described it 

 as Phryssocystic humilis, a new species characterized by having a subanal fas- 

 ciole. The Valdivia took a similar specimen, just south of the Maldives in 

 1252 fms. which Doderlein recognized as de Meijere's species, but because of 

 the subanal fasciole he made it the type of a new genus Meijerea. Like 

 de Meijere he failed to note the identity with Argopatagus. The ALBATB068 

 took, at a depth of 670-G97 fms. among the Hawaiian Islands, a similar speei- 



