NO. 1205. SYNOPSIS OF THE XJfADESSIMPSOX. 827 



(Group of Nodularia fissidens.} 



Shell solid, compressed, subelliptical to subrhomboid, with rather 

 full beaks, which have radiate, corrugated sculpture extending out on 

 the disk as wavy sulcations, and changing near the edge to plain 

 sulcations; posterior ridge low, rounded; hinge strong; right valve 

 with two pseudocardinals, the lower the larger, showing a tendency to 

 split up, and having a gape in the plate behind, and having one lateral; 

 two pseudocardinals in the left, somewhat split, and two laterals; 

 muscle scars deep, distinct. 



NODULARIA FISSIDENS Bottger. 



* Uio(Hyridella)Jis8iden8BiyrTG'ER,Ber. Senck. Ges., 1886, p. 27, pi. n, figs. 6ab,lab. 



Kalahari Desert. Southwest Africa. 



NODULARIA HYGAPANUS Bottger. 



* Unto (Hyridella) hygapanus BOTTGER, Ber. Seuck. Ges., 1886, p. 26, pi. n, fig. 6. 



Kalahari Desert. I am not certain as to the relationships of these two 

 species. 



Genus HARMANDIA Roehebrune, 1882. 



^Type, Harmandia somboriensis Rochebrune.) 

 Harmandia ROCHEBRUNE, Bull. Soc. Phil., VI, 1882, p. 45. 



Shell subtrapezoidal, subalate, rather thin, posteriorly compressed, 

 with low beaks and irregularly radial sculpture, a few of the ribs con- 

 verging at the center of the disk, the rest becoming divaricate and 

 covering the shell, those of the posterior slope springing from the rib 

 on the low, posterior ridge; epidermis gray green; left valve with two 

 arcuate, compressed, elongate pseudocardinals in front and a triangular 

 cardinal under the beak, the right with two pseudocardinals in front 

 and a pit under the beak ; there are two nearly straight lamellar laterals 

 in each valve, and a small, up curved lamella above them near their 

 posterior ends ; anterior muscle scars deep ; nacre white, brilliant, show- 

 ing the outside sculpture. 



Animal unknown. 



HARMANDIA SOMBORIENSIS Rochebrune. 



* Harmandia somboriensis ROCHEBRUNK, Bull. Soc. Phil., VI, 1882, p. 46, pi. i, figs. 

 1-3.. 



Eapids of Sombor sombor, Mekong. 



Genus GRANDIDIERIA Bou^guignat, 188S. 



(Type, Unio bitrtoni Woodward.) 

 Grandidieria BOURGUIGNAT, Bull. Soc. Mai. Fr., II, 1885, p. 6. 



Shell small, oval, rounded or rhomboid, solid, much inflated, generally 

 narrowly biangulate behind, often apparently of two forms, one more 



