A MONOGRAPH OF THE EXISTING CRIXOIDS 



503 



balanoides 



Centrodorsal half again as high as 

 broad at the base. 



Interradial furrows on the centro- 

 dorsal deep, broader than the cirrus 

 sockets. 



Columns of cirrus sockets in each 

 radial area separated by a median 

 furrow not so broad as the cirrus 

 sockets. 



Cirrus segments 35-40, the longest not 

 over 3 times as long as broad, and the 

 distal all markedly longer than broad. 



SjTiarthrial tubercles developed. 



elongata 



Centrodorsal nearly 3 times as high as 



broad at the base. 



Interradial furrows on the centrodorsal 



shallow, only about half as broad as 



the cirrus sockets. 



Columns of cirrus sockets in each radial 



area separated by a narrow median 



line, not a furrow. 



Cirrus segments 27-35, the longest 

 about 4 times as long as broad or even 

 longer, and the terminal 10 as long as, 

 or only slightly longer than, broad. 

 Synarthrial tubercles absent. 



From this comparison it would seem that the only differences of importance 

 between balanoides and elongata lie in the longer centrodorsal and the longer earlier 

 cirrus segments of the latter. Considering the fact that both specimens came from 

 the same region and were taken at practically the same depth, it seems safe to consider 

 the former to be the result of individual variation, and the latter as indicating imma- 

 turity, and thus correlated with the slightly lesser number of cirrus segments and the 

 absence of sjmarthrial tubercles. 



Localities.- — Challenger station 201; off Mindanao, Philippine Islands (lat. 7°03' 

 N.,long. 121°48'E.); 150 meters; stones and gravel; October 26, 1874 [P. H. Carpenter, 

 1881, 1888; A. H. Clark, 1913] (1, B.M.). Type locahty. 



Albatross station 5178; near Romblon, Phihppine Islands; Point Origon (N.) 

 bearing S. 5° E., 2.3 miles distant Gat. 12°43'00" N., long. 122° 06'15" E.); 142 meters; 

 fine sand; March 25, 1908 [A. H. Clark, 1908] (1, U.S.N.M., 25449). 



History. — It was the tj'pe specimen of this species to which Carpenter referred in 

 1881 when, m remarking upon a peculiar species dredged by the Blake in which Pi 

 and Pa are absent (subsequently called by him Antedon [now Hypalometra] dejecta), 

 he mentioned that the Challenger had dredged a specimen near the Philippine Islands 

 which presented the same peculiarity. 



Carpenter described and figured this species in 1888 from a single mutilated ex- 

 ample, and in 1908 I described as elongata another mutilated specimen which I now 

 feel sure is conspecific wath it. 



Genus ADELOMETRA A. H. Clark 



Antedon (part) P. H. Carpenter, Proc. Roy. Soc, vol. 28, 1879, p. 384, and following authors. 



Adelomelra A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 363 (diagnosis; type species 

 Antedon angustiradia P. H. Carpenter, 1888); Bull. Mus. Comp. Zool., vol. 51, No. 8, 1908, p. 248 

 (same); Proc. Biol. Soc. Washington, vol. 21, 1908, p. 136 (referred to the Antedonidae) ; Proc. 

 U.S. Nat. Mus., vol. 34, 1908, p. 211 (referred to the Antedonidae, restricted); Amer. Nat., 

 vol. 42, No. 503, 1908, p. 724 (color); Proc. Biol. Soc. Washington, vol. 22, 1909, p. 176 (referred 

 to the Zenometrinae) ; Crinoids of the Indian Ocean, 1912, p. 10 (absent from Japan), p. 26 



