28 NILS HJ. ODHNER, MOLLUSOCA. 
istic oblique rugations on the anterior part of the shell. -— Distribution: E. Africa; 
Seychelles (v. MARTENS 1880); Philippines (REEVE); Queensland (HEDLEY 1910). 
C. (Laevicardium) biradiatum BRUGUIERE. 42 miles W. S. W., 70 feet ("?/s), 
1 sp., I. 26 mm, like fig. 49 in REEvE 1844. Distribution: Seychelles (Vv. MARTENS 
1880); Maldives and Laccadives (E. A. SmiTtH 1903); Ceylon, Andaman I., Amirantes, 
Seychelles (MELVILL 1909); Philippines (REEVE); Queensland (HEDLEY 1910). 
C. (Papyridea) papyraceum CHEMNITZ. 48 miles W. S. W., 78 feet (""/1), 2 sps, 
1. 19 and 11 mm. — Distribution from the Persian Gulf and Suez to Natal, Philip- 
pines and Japan; N. and E. Australia (LYNGE 1909). 
FAM. CHAMIDAE. 
Chama lazarus LINnnÉ. 45 miles W. S. W., 60—66 feet (””/s), 2 sps and 2 
valves, max. h. (sp.) 43 mm. This species is one of the most characteristic of the 
genus and is well reproduced by REzrvE (Conch. Icon. 4, 1846, PI. II, fig. 4). Its 
colour is white, with 2—3 reddish brown rays on the posterior half of the shell, and 
a lemon yellow tint on the umbones; the inner side is uniformly white, finely grained, 
and striped radially. Characteristic are, further, the broad erect, somewhat undul- 
ating or foliaceous lamellae which extend over the whole shell and in the umbones 
are simple and even, not undulating or subspinulose, as in most of the Chamidae; 
the posterior muscular impression is lengthened ovate and does not reach the base 
of the hinge plate; the smooth marginal zone of the valves (out of the mantle line) 
is rather broad, about half as broad as the muscle scars. 
To this species I refer Chama pulchella REEvVE (Conch. Icon. 4, 1846, fig. 10 a), 
a species in which RBEEVE comprised not only dextral but also sinistral shells. He 
figures in fig. 105 a specimen with the umbones turned from right to left, which, 
in its exterior appearance (colour and sculpture) is strikingly similar to the dextral 
fig. 10a. Nevertheless, the specimen 10b must be distinguished from that of fig. 10 a 
and referred not only to a distinct species but also to a new genus, Pseudochama, com- 
prising the sinistral Chamas and characterized by differences in dentition and ana- 
tomy (see below). Through the kindness of Mr. S. F. HARMER, I got an opportunity 
of comparing photographs of the two forms in question from the inside, and they 
show the most apparent agreement with the typical conditions in either genus. Ch. 
pulchella of REEVE consequently must be restricted to the dextral specimen of fig. 
10 a, and for that of 10b I propose the new specific name Pseudochama similis. 
Even in the most recent manuals and other publications dealing with the Cham- 
idae, one meets with the statement that in Chama the umbones are turned to the 
right or to the left indifferently even in the same specimen;' but no other example 
of this condition is said to be known than the above named Ch. pulchella (in REEVES 
1! Only ANTHONY (1905) remarks that ne has never found both conditions prevailing within one and the 
same species. 
