DALL] NEW LAND-SHELLS FROM CENTRAL MEXICO 193 
SPHARIUM MEXICANUM n. sp. 
(PLatE XLIV, FicuRE 6) 
Shell small, shape subrhomboidal, the ends nearly equally rounded, 
the beak nearer the anterior end; protoconch smooth, ovate, not 
prominent ; umbonal region with about ten concentric waves (sharp 
at the crest, the interspaces wider) outside of which the sculpture 
suddenly becomes much less prominent, in fact hardly more than 
concentric striation ; the surface is covered with a pale olive perios- 
tracum; right valve with a single rather obscure cardinal, and a pair 
each of disproportionately strong anterior and posterior lamine, 
the inner faces of which show distinct fine granular rugosity ; pallial 
line obscure, adductor scars distinct. Length 5.5, height 4.25, diam- 
eter 3.0mm. ‘Type, 110,405 U.S. Nat. Mus. 
Habitat.—Alvarez Mountains with the preceding. 
This is very distinct from any other North American species, and 
with the exception of S. costaricense Prime, is the most southern of 
them all. Unfortunately only a single valve was obtained, though 
this is in perfect condition. 
SPECIES OBTAINED ON OTHER OCCASIONS 
The following species are recorded as obtained by Dr. Palmer 
on other occasions at the localities mentioned. 
Physa berendti Dunker. Twenty-five miles southeast of Sal- 
tillo, and at Santa Maria del Rio. 
Physa mexicana Philippi. Nombre de Dios, Durango, and at 
the town of Durango. 
Physa boucardi Crosse and Fischer. Nombre de Dios, Durango. 
Planorbis tenuis Philippi. Nombre de Dios. 
Planorbis liebmanni Dunker. Topolobampo, Sinaloa. 
Planorbis tumidus Pfeiffer. Nombre de Dios. 
Othalicus undatus Bruguiére. Manzanilla, Colima. 
Praticola berlandieriana Moricand. “ Mexico.” 
Praticola griseola Pfeiffer. “ Mexico.” 
Polygyra carpenteriana Bland. “ Mexico.” 
Bulimulus schiedeanus Pfeiffer. ‘‘ Mexico.” 
The four immediately preceding species were probably obtained 
at some point on the low coastal plain of northeast Mexico. 
Anodonta exilior Lea. Durango City. 
Doctor Palmer has collected a considerable number of other in- 
teresting mollusks, at various times, which have been put in the 
National collection without retaining a list, and which therefore 
cannot be enumerated here. 
