216 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the tube feet 3Ir?naster is removed from proximity to Leptychastei\ 

 iiii association suggested by the dorsal surface, including the mar- 

 ginals, while it can not be placed in the Ganeriiclae because it pos- 

 sesses superambulacral plates and lacks the heavily calcified internal 

 interbrachial pillar, the reticulated, imbricated, abactinal skeleton, 

 nnd the asterinoid abactinal armature of C'ycethra and Ganeria. 



In Mimaster the membranous interradial septum forms a complete 

 partition from the side wall of the disk to a free margin close against 

 the stomach; but in Cycethra and in Ganeria (as in Solaster and in 

 Asterina) there is a rigid pillar running from above the mouth plates 

 to the abactinal surface, the coelom being undivided between this 

 pillar and the margin (an incomplete calcified septum). 



In this connection I would like to call attention to the resemblance 

 between Ganeria and the Solasteridae. The marginal plates of 

 GaneHa falklandica are essentially like those of Solaster, and in the 

 adambulacral armature we find a very generalized form of the 

 peculiar pectinate tj^pe of the Solasteridae. The form and armature 

 of the mouth plates, the actinal intermediate plates, and even the 

 adambulacral plates can, however, be more nearly matched in the 

 Asterinidae. The abactinal skeleton, though of an open reticulate 

 form, especiall}^ on the disk, is more nearly like that of the Aster- 

 inidae than like that of the Solasteridae. 



While perhaps in some way related to the Ganeriidae. I think 

 Mimaster is well within the Phanerozonia. Gephyreastei\ which I 

 formerlj^ associated with it in the Mimasterinae, and Priamaster 

 Koehler seem to belong in this family in a special subfamily, the 

 Priamasterinae.^ The internal anatomy of Priamaster has not been 

 described. 



The purely nomenclatorial side of the matter is complicated by 

 RacUaster elegans Perrier. Through the kindness of Dr. H. L. Clark 

 I have examined the type (unfortunately dried) in the Museum of 

 Comparative Zoology (No. 909, Dominica, West Indies, 98*2 fath- 

 oms). From every outward indication this species is a typical 

 Mimaster. Radiaster has one year priority. 



Subfamily Radiasterinae Fisher. 



SYNOPSIS OP THE GENERA OP RADIASTERINAE. 



a\ Gonads confined to the disk and consisting of several tnfts springing from 

 ' a common point close to the interbrachial septum ; hepatic coeca with 

 long subdivisions, so that each ray appears to have from six to ten sepa- 

 rate coeca of unequal length ; tube feet with well-developed sucking 

 disks ; lateral abactinal plates not cruciform nor regularly imbricated. 



Radiaster'- Perrier. 



1 Fisher, Wild, p. 172. 



= Component species: Radiaster elegans Perrier, genotype; R. tizardi (Sladeii) ; R. nota- 

 hilis (Fislier). 



