22 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



At the base of the segment is a large prominent median elevation or 

 tubercle. The inner innnovable branch of the uropoda is long and 

 narrow, leaf -shaped, and pointed at the extremity. The outer branch 

 is a little shorter than the inner branch and has the posterior extremity 

 rounded. The cndopod and exopod of the fourth pleopod are similar, 

 rather Heshy, with transverse folds, and without marginal sette. The 



exopod of the third pleopod 

 is two-jointed. 



All the legs are ambulatory 

 in structure. 



This genus, to which Cymo- 

 doce darxolnii Cunningham* 

 should be referred, comprises 

 as yet but two species. The 

 present one differs from Cas- 

 sldias darwinii in the much 

 longer exopod of the uropoda, in the much larger median tubercle 

 on the terminal abdominal segment, and in the more shallow notch at 

 the extremity of this segment. 



Two specimens, both females, come from off liio de la Plata, Argen- 

 tine Republic. They were collected b}^ the U. S. Bureau of Fisheries 

 steamer Albatross in 1887, at a depth of lOi-lli fathoms, among sand 

 and broken shells. 



The type is in the U. S. National Museum, Cat. No. 32249. 



« Trans. Linn. Soc. London, XXVII, 1871, pi. lix, figs, la, b; Studer, Abhandlungen 

 d. Koniglichen Akademie d. Wissenschaften zu Berlin, 1883, pp. 18-19, figs. 6a, b; 

 Dollfus, Mission Scientifique du Cap Horn, 1891, pp. 65-66, pi. viii, figs. 8a, b. 



Fig. 27. 



-Cassidias darwinii. a. Lateral 

 Abdomen, h. Abdomen. 



