200 HAWAIIAN AND OTHER PACIFIC ECHINI. 



exceedingly difficult to separate from each other satisfactorily and there has been 

 much confusion as a consequence. When the Revision of the Echini was pub- 

 lished, Mr. Agassiz recognized but two species, luzonica from the East Indies 

 and lyrifera from the eastern Atlantic. Since then no fewer than eleven Recent 

 species have been proposed. The attempt to recognize these thirteen species 

 and prepare a key by which they could be distinguished has led me finally, 

 after examining more than 400 specimens, to the conclusion that eight species 

 are all that can be really distinguished and it is possible that one or two of these 

 are simply extreme variants of the most wide spread species. As for the genera 

 Kleinia and Toxobrissus, it seems hopeless to try to separate them from Brissopsis. 

 Mortensen's careful work (1907, Ingolf Ech., pt. 2, p. 152-168) has revealed 

 good specific characters not hitherto recognized and has resulted in making 

 clear the limits of lyrifera and the separation therefrom of at least three recog- 

 nizable forms. I cannot follow him, however, in attempting to differentiate 

 a variety capensis for the form of lyrifera found near the Cape of Good Hope. 

 I think we have here, as in the case of Brisaster fragilis, a north Atlantic species 

 occurring in South African waters. Such cases demand more careful study 

 and much more abundant material before their true status can be determined. 

 The East Indian species luzonica is even more variable than its Atlantic congener 

 and its geographic range, as far east as Hawaii, is even greater. In our prelimi- 

 nary reports (1907, Bull. M. C. Z., 50, no. 8 and 51, no. 5) Mr. Agassiz and I 

 not only attempted to distinguish oldhami from luzonica, but described from a 

 single specimen, a third species, circosemita. Since then Dr. Koehler has pub- 

 lished his important report on Indian spatangoids (1914, Ech. Indian Mus. : 

 Spat.) in which he recognizes six species of Brissopsis from the Indo-Pacific 

 region. His descriptions are most detailed and his figures excellent and very 

 useful. A careful study of all the specimens accessible, in the light of Morten- 

 sen's and Koehler's publications, satisfies me that oldhami is only a form of 

 luzonica which is not even worthy of varietal rank; that circosemita is a young 

 luzonica with certain individual peculiarities that do not warrant the retention 

 of the name; that duplex, lemonnieri, and bengalcnsis are all best referred to 

 luzonica; and that parallela may possibly prove to be only an extreme variant 

 of the same species. The three forms separated from h/rifera by Mortensen. 

 alta, atlantica, and elongata are recognizable but I am not sure as to their real 

 status; alt a may be a hybrid between a Brissopsis and HypseUuter limieolus, 

 atlantica simply a variant of lyrifera and elongata, a variant in another direction. 

 It is evident therefore that more- material and more stndv are neeessarv before 



