578 PROCEEDINGS OF THE NATIONAL MUSEUM. 



t PSEUDOSPATHA LIVINGSTONENSIS Bourguignat. 



* Spatha tanganyicensis Smith (part), Proc. Zool. Soc. LoncL, 1880, pi. xxxi, fig. 8a; 



1881, p. 296, pi. XXXIV, fig. 32. 



* Burtonia living stonensia Bourguignat, Moll. Fluv. Nyanz., 1883, p. 20. 



* Burtonia elongata Bourguignat, Un. and Ir. Tan., 1886, p. 31 ; Icon. Mai. Tan., 



1888, pi. XXV, fig. 3. 

 '* Burtonia contorta Bourguignat, Un. and Ir. Tan., 1886, p. 39; Icon. Mai. Tan., 

 1888, pi. XXVI, figs. 3-5. 



Lake Tanganyika. 



PSEUDOSPATHA SUBTRIANGULARIS Bourguignat. 



* Burtonia siibtriangularis Bourguignat, Un. and Ir. Tan., 1886, p. 35; Icon. Mai. 



Tan., 1888, pl.xxv, fig.2. 

 ^Burtonia grandidieriana Bourguignat, Un. and Ir. Tan., 1886, p. 42; Icon. Mai. 

 Tan., 1888, pi. xxvii, figs. 1-3. 



Lake Tanganyika. 



PSEUDOSPATHA BOURGUIGNATI Bourguignat.' 



* Burtonia bourguignati'BoURGiJiGn AT, Un. and Ir. Tan., 1886, p. 38; Icon. Mai. 



Tan., 1888, pi. xxvii, figs. 4-5. 



Lake Tanganyika. 



The following species are unfigured and unknown to me. 



* Burtonia jouherti Bourguignat, Un. and Ir. Tan., 1886, p. 40. 



*" Burtonia hridouxi, Bourguignat, Un. and Ir. Tan., 1886, p. 40. 



All from Lake Tanganyika. 



Genus HYRIOPSIS Conrad, 18§3. 

 (Type, Vnio delphinits Gruner.-) 



Ryriopsis Conrad. Pr. Ac. N. Sci. Phila., 1853, p. 269. 



Shell large, compressed, rhomboid-elliptical, dorsally winged and gen- 

 erally biaugulate behind, sometimes produced in the post-basal region; 

 beaks low, mostly compressed, the sculpture consisting of numerous 

 concentric ridges nearly parallel with the growth lines, generally 

 extending well on to the disk of the shell, the earlier ones fine, oiten 

 slightly nodulous or doubly looped; epidermis olive to brown, some- 

 times faiutly rayed; pseudocardiuals two or three in the left valve, one 

 to three in the right, when youug compressed, but often breaking into 

 irregular denticles when old; laterals long, compressed, two in the left 

 valve and one in the right, sometimes vertically striate, the left valve 

 often having a sort of raised lamellar tooth at or just behind the beak. 



' Said to be of Jonbertin the literature. 



■2 The general make-up of the shells of this genus, Cyclomya, and Crisiaria seems to 

 indicate close relationship to each other, and a not distant one to the subgenus 

 Fropiera of LampaHi^i, and I should not be surprised to learn tliat the marsupium 

 occupies the posterior part of the outer gills in distinctly marked ovisacs. 



