10 



CEYLON PEARL OYSTER REPORT. 



Family : ETJRYDICID.E. 

 (Cirolanidse of Harger, Hansen, Bonnier, Stebbing, Norman, and others.) 



Among the genera that have been assigned to this family, Eurydice, Leach, 1815, 

 is beyond dispute the earliest, so that the name Cirolanidse, notwithstanding the 

 distinction conferred upon it as the title of Hansen's notable work in 1890, is bound 

 to give way to Eurydicidae. Another generic name has " page precedence " over 

 Cirolana, since in 1818 Leach established Nelocira as his tenth genus of Cymothoadae, 

 and Cirolana as the eleventh, assigning a single species to each respectively, Nelocira 

 swainso?ri and Cirolana cranchii. These are now considered to be one and the same 

 species. The only distinction between them which Leach supplied was that the 

 pleon of Nelocira. had five segments and that of Cirolana six. As, therefore, the 

 generic character of Nelocira is erroneous, it is just that the preference should be 

 given to the correctly described Cirolana, and this has been done by general consent. 

 It is, moreover, convenient, because Nelocira is apt to be confused with the very 

 similarly named but quite distinct genus which Leach at the same date called 

 Nerocila. 



The family at present includes seven closely connected genera, distinguished in the 

 following synoptic table : 



r Pleon forming only two distinct segments. 1. Colopisthus, H. Richardson, 1 

 1 < Pleon forming more than two distinct 

 I segments 2. 



fEyes absent; peduncle of uropods with 2. Cirolanides, Benedict, 1896. 

 inner apex not produced. 

 Eyes present ; peduncle of uropods with 

 inner apex produced 3. 

 ' Peduncle of second antennae four-jointed ; 

 maxillipeds without hooks on second 

 joint, 

 Peduncle of second antennae five-jointed ;* 

 maxillipeds with hooks on second 

 joint 4. 

 r First pleopods with inner branch broad. 4. Cirolana, Leach, 1818. 

 4< First pleopods with inner branch nar- 

 L row 5. 



f Head and trunk broad. 

 5 < 



LHead and trunk narrow 6. 



902. 



3. Eurydice, Leach, 1815. 



5. Hansenolana, Stebbing, 1900. 



* With regard to a sixth joint in this peduncle in Cirolcma, Conilera and Bathynomus, see Hansen, 

 'Journ. Linn. Soc.,' vol. 29, p. 339. 



