OPHITJEOIDEA FROM THE KOREAK SEAS. 447 



immature OpJiiopJioUs, the common associate of the well-known 

 forms just mentioned. The group of AmpliiurcB and Hemipliolis, 

 to which, the Korean specimens belong, is characterized by the 

 small number of mouth-papillfe ; and they are allied to Amphiura 

 Jiliformis and A. squamata, both Atlantic forms. The new species 

 of OpMonereis and Ophiotliela I have also recognized in a small 

 collection of undescribed Opliiurce from the Eed Sea. The 

 Opliiothrix of the Korean seas, with its numerous glassy spines 

 and extremely variable disk and colour, does not come within any 

 of the specific diagnoses of that very large genus, which is so fully 

 represented in the Philippine seas. 



Lyman and Liitken, especially, have shown the mimeticism and 

 the similarity of generic and specific groupings of Ophiuroidea on 

 both, sides of the Isthmus of Panama, and the interesting repre- 

 sentative character of the Ophiuroid faunas of the eastern African 

 seas and of seas around the islands of the Pacific. 



Having this world-wide distribution of closely-allied forms to 

 deal with, it is not surprising that the difficulty of discriminating 

 the species of large genera should be great. To this difficulty is 

 added the extremely unsatisfactory multiplication of genera that 

 has taken place, specific attributes often being regarded as 

 generic, and parts of the generic diagnoses being frequently appli- 

 cable to the type species and no other. It has been necessary 

 to modify one genus, and to suggest the absorption of another after 

 the examination of the form which I have termed Ophiolepis 

 mirahilis : and in the instance of Semipholis microdiscus a part of 

 the Agassizian diagnosis must be discarded. One of the OpMo- 

 glyphcB is very like an Ophiomusian ; and the remarks upon it 

 will be found after the description of the species. 



The fauna of Ophiuroidea, the result of dredging over a wide 

 sea-floor, if it is an average of the whole, denotes conditions un- 

 favourable to the large growth of individuals. The number of 

 genera (ten) is small ; and the excess of Opliioglyplice is as remark- 

 able as is the absence of several genera common in the Pacific. 

 Thus OpMocnemis,OpMopeza, OpMoplocus, OpMocoma,Ophiarac]ina, 

 Ophiarthrum, Fectinura, and OpMopsmnmium are not represented. 



As a whole, the fauna is that of shallow water. 



