132 Mr. J. Wood-Mason on tin' Ocuits Doldamia. 



latoly discovered by the 'Cliallenji:er,' and upon whicli Dr. 

 V. "\Villenioes-fc?uhm (one of the naturalists to the expedition) 

 had bestowed the name Deidamt'a, had long before been de- 

 scribed by Professor Caniil Heller under the name oi Poli/cheles 

 ti/j)/ih'jts. In this remarkable Crustacean the organs of vision 

 are morphologically entirely wanting, just as in Deiilamia^ 

 the ])osition of the eye-stalks being merely indicated by two 

 small black specks. The name Dcidamia having been held 

 to be inadmissible *, as having been already em])loyed for a 

 valid genus in another division of Arthropoda, and Willemoesia 

 substituted for it upon the daring ana, as it seems to me, 

 dangerous assumption that every animal dredged uj) from so 

 vast a de])tli as were the Deidnwur would prove generically 

 ditlerent from every thing previously described, I have thought 

 it worth while to translate, for publication in the 'Annals and 

 Magazine of Natural History,' Professor Heller's later and 

 more methodical account of his wonderful blind Crustacean 

 from the Mediterranean. The conclusions that I have arrived 

 at, after a most careful study of Heller's figures and descriptions 

 in comparison with those published in Prof. Wy ville Thomson's 

 Reports, are : — 



1. That the three species PoIycheUs typhlops, Deidamia 

 leptodactylaj and D. crucifer cannot be placed in any existing 

 family of crustaceans, recent or fossil, except perhaps the 

 Eiyonidaj, the structural characters of whicli are too incom- 

 pletely known at present to admit of their being included 

 in it. 



2. That the three species in question belong naturally to 

 one and the same family. 



3. That they cannot be distinguished from one another even 

 generically. 



I therefore beg to propose for them a new family name, and 

 to regard all three as members of its single genus PolycheleSy 

 as follows : — 



Fam. nov. Polychelidae. 

 Genus unic. Polycheles, Heller. 



a. With the four anterior pairs of wuRiruj-legs didactyle. 



Species 1. Polycheles typhlops, Heller. 



2. crucifer^ v. W.-S. 



b. With all the walkiny-leys didacti/le. 



3. Polycheles leptodactyhtj v. W.-S. 



♦ 'Nature,' 1873, vol. viii. p. 485: 1874, vol. ix. p. 182. 



