344 
vielleicht nur eine verlängerte, aufgeblasene, wenig skulptierte Form von ihr. Der Besitz’ 
der Faltenskulptur auf der Area ist zur Beurteilung von Verwandtschaftsbeziehungen nicht 
Ausschlag gebend, bei allen den zur Gruppe des Pseud. inoscularis gehörenden Arten 
ist eine ausgesprochene Neigung zur Rückbildung der Arealfalten unverkennbar nnd gipfelt 
bei dem nun folgenden Pseud. cumingii Lea, bei dem nur noch ganz schwache Fältchen. 
vorhanden oder alle Anzeichen einer Arealskulptur verschwunden sind. 
26. Pseudodon (Pseudodon) cumingii Lea. 
Taf. 43, Fie. 13. 
Anodonta cumingii Lea, Proc. Zool. Soc. London, 1850, 8. 199. — Musgrave, Phot.. 
Conch., 1863, Taf. 1, Fig. 6. 
Margaron (Monocondylaea) cumingii Lea, Synopsis; 1852, S. 50; 1870, S. 73. 
Monocondylaea cumingii Lea, Journ. Acad. Nat. Sciences, Philadelphia, Vol. 4, 1860, 
S. 235, Taf. 33, Fig. 114; Observations, Vol. 7, 1860, S.53, Taf. 33, Fig. 114. 
Anodon cumingii Sowerby in Reeve, Conch. Icon., Vol. 17, 1870, Taf. 31, Fig. 122, 
Microcondylaea cumingii Clessin in Martini-Chemnitz, Ill. Conch. Cab., Genus Ano-: 
donta, 1876, S. 253, Taf. 83, Fig. 3—4, 
Psendodus cumingii de Morgan, Ball. Soc. Zool. France, 1885, Vol. 10, S. 422. 
Pseudodon eumingii Simpson, Synopsis, 1900, S. 837; Descript. Catal., 1914, S. 1089._ 
Pseudodon cumingi H. Fischer & Dautzenberg, Mission Pavie, 1914, S. 436. 
Testa laevi, obovata, compressa, inaequilaterali, postice subbiangulata,; valvulis sub- 
erassis; natibus vin prominentibus,; epidermide atro-fusca,; dentibus cardinalibus lobatis, in 
utroque valvulo unicis; margarita alba et iridescende. 
Shell smooth, obovate, compressed, inequilateral, subbiangular behind; substance of the- 
shell somewhat thick; beaks scarcely prominent; ligament long, rather thick and dark brown; 
epidermis blackish brown, darker and minutely striate on the anterior portion, lighter and 
shining in the middle, marks of growth rather distant; umbonial slope raised and rounded;. 
posterior slope raised into a hich carina, with two raised lines passing from the beaks to 
the posterior margin and also with some obscure small folds towards the beaks; cardinal 
teeth small, with a single lobe in each valve, the right one being the larger and locking in 
anteriorly to that in the left valve; anterior eicatrices confluent and well impressed; posterior 
eicatrices confluent, rather large and slightly impressed; dorsal cicatrices well impressed and 
placed in a row across the centre of the cavity of the beaks; cavity of the shell rather 
shallow and rounded; cavity of the beaks very shallow and rounded; nacre white and 
iridescent. 
Diam. 1, lingth 1,9, breadth 3 inches. 
Hab. Malacca. 
Lea. 
