272 bulletin: museum of comparative zoology. 



ereda and Liitken's Ophiophragvms septus described in 1859. I think 

 therefore that Koehler's specific name must be considered a synonym 

 of Liitken's. 



There are in the M. C. Z. collection some beautifully preserved 

 specimens, young and adult, of Ophiocnida filogranea Lyman, collected 

 by Mr. George M. Gray in 1915, at Port Tampa, Florida. These 

 specimens, the largest of which is almost exactly like the holotype of 

 0. filogranea, agree surprisingly well with typical Ophiophragmus 

 wurdemanii, except in one particular, the covering of the interbrachial 

 areas below. There is not the least doubt that they are congeneric 

 with 0. wurdemanii and they might almost be regarded as only a 

 variety of that species. But until an intermediate specimen is found, 

 the specific distinctness may be maintained. As for Ophiolepis chil- 

 ensis M. & T., the reasons which have compelled its transfer to 

 Ophiophragmus are given in detail (p. 277). Finally, I found an 

 undescribed species of the genus at the Tortugas in June, 1917. 



Although there can be no doubt that Ophiophragmus is very closely 

 related to Amphiodia, it seems desirable to recognize it as a separate 

 genus. It is characterized by the presence of the following combina- 

 tion of characters: — Disk-scales moderately to quite coarse, thick; 

 margin of disk with a more or less developed series of erect papillae; 

 upper arm-plates broadly in contact, two — six times as wide as long ; 

 oral papillae three on each side, the distal one widest, the proximal 

 thick and block-like, as in Amphiura; under arm -plates more or less 

 tetragonal; arm-spines, three; tentacle-pores large; tentacle-scales 

 two, one on under arm-plate and one on side arm-plate, often sepa- 

 rated from each other because of the large size of the tentacle. As 

 thus defined the genus is known only from the Caribbean region (north 

 to North Carolina, south to Tobago), and from the western coast of 

 Central and South America. The species may be distinguished from 

 each other as follows : — 



Key to the Species of Ophiophragmus. 



a Arms long, 6-17 times disk-diameter; 9-15 series of scales in interradial 

 areas at narrowest point. 

 b Basal under arm-plates wider than long. 



c Marginal papillae of disk, thick, blunt, not spiniform. 

 d Arms slender, 10-17 times disk-diameter. 



e Radial shields broad, length only 1-2 times width; 9-12 series 

 of scales in interradial areas; no longitudinal stripe on lower 

 surface of arm. 



