THE OSTRACODA. 



227 



II. SYSTEMATIC PART. 



In Halocypridse, as in nearly every group of Crustacea, we owe tlie main lines of 

 morphological and taxonomic study to the late Professor Clans. With only a few 

 specimens of comparatively few species at his disposal, chiefly from material obtained 

 by Professor Chun at the Canary Islands, he produced in 1891 (after two pioneer papers) 

 the important monograph ' Die Halocypriden,' which showed the variety and interest of 

 this family. "Whether the wide systematic distinctions to which he called attention are 

 to be utilised to divide " genera" (as Claus did) or " gronps" (which Dr. Miiller prefers), 

 does not seem to be very important. Tliis monograpii was accepted by all intermediate 

 writers till 1906, when Professor Miiller's Report on the Ostracoda of the ' Valdivia ' 

 Expedition appeared ; this has added enormously to our systematic knowledge, and 

 will remain the standard for some time to come ; the taxonomy and synonymy therein 

 laid down have been accepted in the present memoir. 



The descriptions and figures in this part are intended merely to be supplementary to 

 those in Miiller's ' Valdivia' Ueport. Where tliey overlap, the object is to supply ready 

 material i'or comparison of the different stages of the same species. 



Of these stages, that which is l)elieved to be the oldest is termed Stage I., it being in 

 all cases, at present, uncertain at which morphological stage or length the larva is 

 hatched. As it is easiest to jsass from the known to the unknown, the oldest stage 

 available has been made the starting-point in all descriptions. 



Dr. Miiller's synonymy and grouping have been adopted, except for the fact that some 

 of his species have been placed as stages in the life-history of species already known : 

 this suggested linking of " species " is shown in the following table: — 



<f.\C, 



Previous Xame. 

 . >v 



Name of Species. Stage II. 



curta curta. 



daphuoides daplmoides, 



var. minor 

 = lacerta. 



liyalophyllum hvalophylluni. 



loricata loricata. 



magna magna. 



procera procera. 



spiiiirostris spinirostris. 



Stage I. 

 stigmatica. 



daplmoides, 

 var. major. 



lophura. 



cteuophora. 



macrocheira. 



decipiens. 



porrecta. 



The mean length in mm. of each sex at each stage, when possible, is given thus 

 (Mean, 000), and is based solely on my own observations. To have included the lengths 

 given in previous records might have led to error, as taking for granted that the mean of 

 a stage is the same at every geogiapliical position and sea-climate ; this is probal)ly not 



SECOND SERIES. — ZOOLOGY, VOL. X. 39 



