AMNICOLA. 435 
8. Amnicola costaricensis. (Tab. XXIL. fig. 6.) 
Hydrobia costaricensis, Mirch, Malak. Blitt. vii. p. 67 (1860-61)'; v. Frauenf. Verh. zool.-bot. 
Ges. Wien, xiv. p. 594 (1864) , 
A very small shell, with convex whorls (4) and narrow perforation. 
Long. 2, diam. 14; apert. long. 1, diam. % millim. 
Hab. Cuxtrau Costa Rica: Rio Torre (Torres) (Dr. Ersted, 1846-4812); San José, 
in an irrigation-tube (Biolley, March 1891). 
Biolley’s shell is somewhat incrusted, so that I can add nothing to Mérch’s description 
. of its surface. 
9. Amnicola (?) seemanni. 
Hydrobia seemanni, v. Frauenf. Verh. zool.-bot. Ges. Wien, xiii. p. 1025 (1863) *; xiv. p. 645 
(1864) *; xv. p. 1, t. 8. fig. 1°; Fisch. & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 271‘. 
Hab. N. Centrat Mexico: Durango, in small streams (Dr. Seemann 1-4, in coll. Cuming ; 
Mus. Vind. Ces.). 
Pilsbry (Nautilus, xii. no. 11, p. 122) suggests that this species may be a smooth 
variety of Tryonia protea, A. Gould, which occurs in the Colorado Desert. 
10. Amnicola subangulata, sp.n. (Tab. XXII. fig. 5.) 
Bythinella sp., Biolley, Moluscos terr. y fluv. de Costa Rica, p. 18 (1897) ' 
Testa conoidea, subangulata, imperforata, solida, fusca, levigata; anfr. 5, regulariter crescentes, plani, ultimus 
peripherice subangulatus, basi convexus ; apertura sat obliqua, ovata, supra angulata, peristomate simplici, 
crassiusculo, margine externo parum, margine basali late rotundato, margine columellari leviter concavo, 
callo parietali distincto. 
Long. 4, diam. 24; apert. long. et diam. 13 millim. 
Hab. Cenrrat Costa Rica, Rio Torres, in the environs of San José, on stones, 1100 
metres above the sea (Biolley'). 
E. Costa Rica: between Madre de Dios and Rio Hondo, in a small stream 80 metres 
above the sea (Pittier, Nov. 1896). 
In general appearance this species resembles the brackish-water Hydrobie, such: as 
H. ulve, Penn.; but the indicated locality is that of a true freshwater shell. 
11. Amnicola (?) bakeri. 
Potamopyrgus bakeri, Pilsbry, in Nautilus, v. p. 9 (1891) *; Proc. Acad. Phil. 1891, p. 328, t. 15. 
figg. 9-11?. 
Hab. Centrat Mexico: east of Yautepec (south-east of Cuernavaca), State of Morelos, 
Pacific slope, dug from the bank of a stream (Ff. C. Baker, expedition of Prof. 
Heilprin ! ”). 
42. Amnicola (?) hydrobioides. 
Pyrgulopsis hydrobioides, Ancey, Bull. Soc. Malac. Fr. v. p. 201 (1888) °. 
Hab. Satvapor: Lake of Coatepeque ’. 
55* 
