MUSEUM OF COMPARATIVE ZOOLOGY. 309 



No. 10. — Preliminary Report on the Ophiuridce and Astrophy- 

 tidai dredged in deep zvater between Cuba and the Florida Reef, 

 by L. F. de Pourtales, Assist. U. S. Coast Survey. Pre- 

 pared by Theodore Lyman. 



(Communicated by Professor B. Peirce, Sup't U. S. Coast Survey.) 



I. General Remarks. 



From the small circle of the Caribbean waters there are now known 

 sixty-three species of Ophiurans and Astrophytons, nearly all of which 

 are critically determined. The standard work of Muller and Troschel, 

 published in 1842, did not contain a greater number of well-defined 

 species from the whole world ! Considering their number and their 

 bathymetric range (which goes nearly to 400 fathoms) we are justified 

 in looking upon their faunal data as of real importance. First, then, 

 considered within their own peculiar sea dominion, to what depths do 

 these species descend, and to what shallows do they rise ? A glance at 

 the following table will reply. Those species with which naturalists 

 have been most familiar as " West Indian " are pretty much littoral. 

 The abundant forms of Ophioeoma echinata, Ophiura cinerea, Ophiactis 

 Miilleri, &c, swarm among the sponges and madrepores of the warm 

 shallows. A few descend to 35 or 40 fathoms, as if to reach a hand to 

 their deep-sea relations ; such are Ophiura brevispina and Ophiolepis 

 clegans ; there are even two, Opldostigma isacanthum and Amphiura 

 tenera, that have been found respectively at 75 and 128 fathoms. But 

 these are exceptions, for if the dredge sometimes brings up a littoral 

 brittle-star, it is a straggler and not an inhabitant. Between 15 and 75 

 fathoms there is a mixed region where dwell the more venturesome 

 of the littoral species and certain new-comers, that either recall the 

 European fauna {Ophiogh/pha aeerrata) or seem a continuation of 

 the littoral types {Ophiactis plana, Ophiocnida olivacea). It is be- 

 low 100 and even 200 fathoms that the really neio types are found. 

 The seven new genera herein described have all a maximum depth of 

 more than 100 fathoms, and only one, Ophiothamnus, runs into less 

 than 75 fathom--. All the species below 250 fathoms are either of new 

 genera, or are singular forms of old genera {Ophiocjhjpha falcifera, 



