ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER 11 



known from the Pacific coast of America. Its nearest known relatives are C. variispina 

 (Ludwig), 807 fathoms, off the Paumotu Islands; C. panopla and C. alberti (Fisher), 

 from the Hawaiian Islands; and G. cricophora (Sladen), from off St. Thomas, Virgin 

 Islands", 390 fathoms. It resembles also in a general way the other species noted in 

 the remarks under the generic diagnosis, namely C. encoryne and 0. analoga Fisher, 

 and C. parallela (Koehler). 



Craterobrisinga synaptoma is characterized by the very long genital region and 

 the numerous, irregular, uncrowded costae. G. alberti has a long costal region but it 

 has a small disk, only nine rays, shorter abactinal spinelets, more regular and fewer 

 costae, longer lateral and subambulacral spines, intercostal integumentary prickles, 

 and especially a characteristic arrangement of the first adambulacral plate of adjacent 

 rays. These, instead of being joined as in species with more numerous rays, are 

 separated by the lower ends of the conspicuous first marginal plates. This seems to 

 be a necessary arrangement to complete the circle of plates bounding the actinostome 

 in those forms with fewer than 10 rays. In C. synaptoma the first two adambulacrals 

 of each ray are joined to the corresponding plates of the adjacent ray, and the first 

 marginal plates are smaller and entirely obscured from below by these proximal 

 adambulacrals. 



In C. panopla the adambulacral plates are shorter and higher as seen from the 

 side of the ray, than in synaptoma, the costal region is shorter, the costae are complete, 

 more regular, and closer together, and their spinelets conspicuously shorter. The 

 costae are more often opposite every adambulacral than opposite alternate adambula- 

 cral plates. It is characteristic of panopla that the lateral and subambulacral spines 

 are long and rigid, while in synaptoma they are not, and the lateral spines are more 

 closely placed owing to the more frequent annular costae. In panopla the disk is 

 provided with two sizes of pedicellariae; in synaptoma there are none. 



In 0. variispina the costae are close together. There is a complete arch opposite 

 each adambulacral and in the interval a nearly complete ridge, which does not fuse 

 with an adambulacral. The arches and secondary ridges are quite regular and the 

 narrow strips of intervening integument bear small spinelets. Moreover, the genital 

 region is relatively short. 



Genus BR I SIN GENES Fisher 



Brisingenes Fisher, Ann. and Mag. Nat. Hist., ser. 8, vol. 20, 1917, p. 427. Type, Brisinga 

 mimica Fisher; Bull. U. S. Nat. Mus., 100, vol. 3, 1919, p.. 517. 



Diagnosis. — Closely similar in appearance to typical Brisinga but differing in hav- 

 ing on the margin of disk directly over the first pair of enlarged ambulacral plates of 

 each ray a pair of papulae. There is thus a circle of these papulae, twice as numerous 

 as the number of rays, and the papulae of each pair are separated slightly less than 

 the space between the pairs. Gonads numerous, in close series on either side of each 

 ray; first adambulacral plate and first marginal plate joined for their whole length 

 to the respective plates of adjacent ray; thus there are four closely joined plates in 

 each interradius; a nonmuscular symphysis, or syzygy, between first and second 

 adambulacral plates and between the dorsal part of the second and third ambulacral 

 plates, as in Brisinga. 



