42 MAZATLAN BIVALVES 
Famity DONACID. 
Genus IPHIGENIA, Schum. 
Syn. Capsa, Lam. 1818, (non 1801.) Donacina, Fer. 
69. IpHIGENIA ALTIOR, Sow. 
Capsa altior, Proc. Zool. Soc. 1832, p. 196, (teste C. B. Ad.)-—- 
Mill. Syn. Test. Viv. p. 225.—Hanl. Descr. Cat. p. 86.— 
Hanl. in Suppl. to Wood’s Ind. Test. pl. 14, f. 34.—C. B. 
Ad. Pan. Shells., p. 276, no. 453. 
Shell very variable iu outline, sometimes nearly equilateral, 
sometimes much produced anteriorly, sometimes incurved at 
the posterior ventral margin. The outside has the usual 
olivaceous epidermis. The inside is more or less stained with 
violet. Bifidity of cardinal teeth more or less developed : 
lateral teeth almost evanescent in one valve, absent in the other. 
Smallest specimen measures long.1°, lat. 1°37, alt. °56. 
Longest a in re ony Caos. - i oie 
Aberrant _,, “s CPR A Deere be 05 fF 
Hab.—Gulf of Nicoyia, in coarse gravel, 12 fm. Cuming.— Var. 
Tumbez, thin mud, 5 fm. Cuming.—St. Elena, Jay.—Panama, 
extremely rare, C. B. Adams.—Mazatlan: very common ; 
‘pool & Havre Coll—The Atlantic analogue is I. Brazili- 
ensis. A closely allied species is from the Gambia; Chief 
Justice Rankin, Bristol Mus. 
Tablet 132 contains 5 specimens in the normal state.—133, 
5 specimens more transverse.—134, 5 specimens indented.— 
135, 2 specimens of abnormal growth.—1386, 1 specimen with 
very thin epidermis. 
70, IPHIGENIA PLEVIGATA, P cus. 
This shell is regarded by Dr. Gray as an abnormal variety 
of I. altior. It has much more the shape of I. Braziliensis. 
The most deeply indented I. altior is far removed from it. 
Mr. Cuming has similiar specimens from the same coast, which 
he regards as an undescribed species. I have seen it with the 
name Capsa levigata, but do not know on what authority. It 
is characterized by very overlapping umbos; subcarinated, 
subtruncated posterior side; deep posterior ventral sinus ; 
