Mr. W. K. Fisher's Notes on Asteroidea. 105 



lias been lemoveJ. The fine spiiiulatiou of the disk extends 

 upon the base of the ray. The abactinal integiiii\ent of the 

 ray, aithouoh very delicate, contains a single layer of lattice- 

 work holothuroiii plates, some of which at the very base of 

 the ray bear minute spinelets. From this it would seem 

 that the abactinal wall oi the ray is destined to be similar to 

 that of i^>'e_yeZ/a, unless in the fully adult animals the plates 

 retain their embryonic character. 



The inlerbraciiium resembles that of Bn'sinjeUa, but 

 differs in havino- the first maiginals (those which bouiul the 

 apex of the interbrachial angle) unequal in size, as shown in 

 the accompanying figures (figs. 1 and 2). In Brisingella 

 these plates are equal, and the suture between the interradial 

 ends is on a line with the interradial, or median oral, suture. 

 There is a distinct syzygy between the first and second 

 adambulaeral [jlates. The interbrachia are not so open as in 

 Brisingella^ as the iinier ends of the first adambulaeral plates 

 are normally in contact, or very nearly so. In an adult 

 specimen we would expect to find these plates still closer 

 together. It is worth noting that in FreyeJkister and in 

 Brisinga, s. s., the first nuirginal plates are of unequal size 

 (see figs. 1 and 2, m, of " New Genera and Species of 

 Brisingidse "). Yet in its present juvenile form tiie inter- 

 brachial angle is different from that of either Freyellaster or 

 Brisinga, while the entire absence of costal arches, as well 

 as of gonads, may reasonably be attributed to immaturity. 

 It does not seem possible to identify this problematical form 

 with any other genus, except the even less known Gymno- 

 hrisinga of Studer. 



Gymnohris'inga sarsii (Abhandl. Akad. Wiss. Berlin, 

 Aidiaug, Abth. 2, 1884, p. 13, pi. iii., fig. 5) is based upon a 

 bnsingoid ray only. This lacks a dorsal skeleton, and while 

 the large pedicellaiia figured by Studer is different from those 

 of Ilymenodlscus agassizi, I am quite unprepared to offer an 

 opinion as to the generic distinctness of the two species. 



The Relationships of Labidiaster. — Although Labidiaster 

 is very generally considered to be a member of the Biisiiigidse, 

 I would suggest that it has few essential characters in common 

 with that family. The genus to which it exhibits greatest 

 structural similarity is Coronaster'^ , Terrier. Coronaster 



* See Fisher, " The Asteroid Geuu.s Cuionaster, Perrier,'' Proc. Biol. 

 See. Washington, vol. xxx. pp. 23-26, Feb. 21, 1917. Coronaster includes 

 the following nominal species: — C. i^arfaiti, Perrier, type, C. antonii^ 

 I'errier, C. briareus (\'errill), C. volsellatus (Sladen), C. octuradiatus 

 (Studer), C, bisiJinosus, Ives, C. halicepus, Fisher. I have examined 



