354. Bulletin American Museum of N atural History [Vol. LIT] 
The shell is oval, moderately convex, the anterior end moderately prolonged and 
narrowly rounded; posterior end broadly rounded. The beaks are rather low. The 
surface appears nearly smooth, but under the microscope fine, close striation is 
distinctly seen. Cardinal tooth of the right valve arcuate, bifid posteriorly. Two 
posterior laterals are well developed. The lower anterior lateral is decidedly heavier 
than the posterior, while the upper one is only weakly developed. 
Length, 3.85 mm.; height, 3.25 mm.; semi-diameter, 1.15 mm. 
This species Sean ee, cunt (Fig. 76) and P. landeroint in 
general outline, but it differs from both by the decidedly heavier lateral 
teeth. The right cardinal tooth is heavier than in P. kentanum, and 
strongly bifid, and the shell is relatively longer. 
Other Species of Pzsidiwm Recorded from the Belgian Congo 
Pisidium giraud: Bourguignat 
Pisidium giraudi BouRGUIGNAT, 1885, ‘Notice Prodrom. Moll. Giraud Tan- 
ganika,’ p. 105; 1888, ‘Iconogr. Malacol. Tanganika,’ pp. 41 and 42, Pl. xvitz, 
figs. 5-7. Ancny, 1907, Bull. Scientif. France et Belgique, (5) IX, (1906), p. 255. 
Lake Tanganyika: beach of Mpala (type locality; Giraud Coll.). 
EupPerA Bourguignat 
Eupera Bourcuienat, 1854, Rev. Mag. Zool., (2) VI, pp. 84 and 675 (without 
mention of species). Monotype: Pzrsidium moqunianum Bourguignat = Cyclas 
modioliformis Anton, of South America. The species is described by Bourguignat, 
1854, Rev. Mag. Zool., (2) VI, p. 668 and it is clearly stated that it belongs to the 
group previously called by him Ewpera.} 
Inmosina CuEssin, 1872, Malakoz. Blatter, XIX, p. 160. Type by present 
designation: Cyclas modioliformis Anton=Pisidium moqumanum Bourguignat. 
Spherium subgenus Clessinella L. WAacEn, 1905, Sitz. Ber. Ak. Wis:. Wien, 
Math. Naturw. Kl, CXIV, Abt. 1, p. 171. Monotype: Sphzrium (Clessinella) 
sturanyt L. Waagen. 
The shell is very small, very thin, oblong, inequilateral; the beaks prominent, 
placed in front of the middle. Hinge narrow, curved, with one minute, oblong 
cardinal tooth, parallel to the hinge, in each valve, or none in the right valve; lateral 
teeth as in Sphzerium, single in the left valve, double in the right. 
_Siphons united near the base. Mantle generally spotted with black. 
In the recent fauna this genus is known only from Middle and South 
America and Africa; HE. ferruginea has been recorded also from Mauritius 
and Madagascar. In Africa the shells are usually found inhabiting the 
cavities of the spongy valves of Etheriide. Formerly the genus was 
more widely spread, as there are Kocene species in Europe and western 
_North America, and one has recently been described from China.2 
1The type is not Pisum naraatinin as stated by Germain, 1913, Bull. Mus. Hist. Nat. Paris, p 
295, footnote. al 
*Hupera sinensis Odhner, 1922, Bull. Geol. Surv. China, No. 4, p. 129, Pl. 1, figs. 16-22. Eocene of 
Southern Shansi. 
