278 bulletin: museum of comparative zoology. 



amphiurans of shedding the disk autonomously and about one third 

 of the specimens collected are diskless. But this shedding of the disk 

 was undoubtedly caused in part, if not wholly, by the method of 

 collecting, for it was necessary to dig up a shovelful of sand and sift 

 it through a rather coarse sieve in order to find these mud-loving 

 brittle-stars. The washing of the sand through the sieve was neces- 

 sarily a rough process. 



Ophiophragmus marginatus. 



Amphiura marginata Ltitken, 1856. Vid. med., p. 26. 1859. Add. ad hist. 



Oph., pt. 2, p. 119, pi. 3, fig. 3a, b. 

 Ophiophragmus marginatiis L>TQan, 1865. lUus. cat. M. C. Z., no. 1, p. 132. 



This species does not seem to have been met with since it was 

 described from a specimen taken at Punta Arenas, Costa Rica, and 

 I have never seen a specimen. The distinguishing character given 

 above in the key is well-shown in Liitken's figure but whether it is 

 really an important specific character remains to be proven. Prob- 

 ably the species is valid but just how it differs from the West Indian 

 forms can only be known when the type (or new material) is compared 

 with them critically. 



Ophiophragmus brachyactis. 



H. L. Clark, 1915. Mem. M. C. Z., 25, p. 238, pi. 10, fig. 13, 14. 



The validity of this species can only be determined by more mate- 

 rial. It may be an extreme individual variant of 0. wurdemanii but 

 only large series of the latter species can demonstrate this. The 

 unique holotype was taken in 47 fms., off Sombrero Key, Florida, 

 April 2, 1872. 



Ophionephthys. 



This is not a large genus, only five species having been assigned to 

 it since its establishment by Liitken nearly fifty years ago. But as 

 Matsumoto has treated it as a synonym of Amphiura, it seems to me 

 desirable to reconsider its status. The rediscovery of Ophionema 

 (p. 282) lends added interest to the matter for few will question the 

 validity of that genus, and the species hitherto called Ophionephthys 

 are obviously intermediate between it and those larger species of 



