388 MOLLUSCA. 
Planorbis intermedius (Phil.), Clessin, loc. cit. p. 196, t. 11. fig. 1™. 
Planorbis ancylostomus, Crosse & Fisch. Journ. de Conch. xxvii. p. 341 (1879); Miss. Scient. 
Mex., Mollusca, ii. p. 63, t. 32. figg. 5, 54,6". 
More compressed than P. tenuis, the penultimate and preceding whorls convex on both sides and occupying 
about 3 of the greater diameter of the shell; right side deeply excavated in the centre; on the left side 
only the 2-24 innermost whorls flat, forming a tray-like excavation, the penultimate whorl, on the 
contrary, convex, with a very blunt spiral angular line, which becomes more indistinct in the last whorl. 
Aperture in the full-grown specimens also very asymmetrical, its right margin obliquely ascending, the 
left margin more rounded. 
a. Diam. maj. 20, min. 184, alt. 64; apert. diam. 7, ampl. 73 millim. 
b. ” 20, ” 164, ” 73 ” 8, ” 7 ” 
Cc. ” 203, ” 18, ” 7; 9 7, ” 74 ” 
d. ry) 18, , 15, ,, 63; ” 7, 9 ? ” 
é ” 183, ” 143, 9 53-63 ; 9 7; ” 74 ” 
a. Specimen collected at Vera Cruz by Uhde; 6. Specimen in Dunker’s collection ; c. Measurements taken 
from Dunker’s figure *; d. Crosse and Fischer’s P. ancylostomus; e. Largest of Strebel’s specimens. 
In some examples the last whorl is a little widened near the aperture, and also at two or three other places 
(our fig. 8), which probably indicate former stoppages in the growth. 
Hab. Nortn America: Texas (Lieut. Couch and G. Wurdeman*). 
N. Mexico: Ojo de Agua (Say !). 
EK. Mexico: Vera Cruz (Uhde*®; Strebel®; De Cande; Sallé5 36; Heilprin®; [neb- 
mann“; Hoge): Jalapa (Hoge) ; Orizaba (Heilprin 8). 
S.E. Mexico: Chiapas (Sallé 15 16), 
Yucatan: Shkolak (Heilprin 3°). 
ANTILLES: Cuba (Pfeiffer?*?; Gundlach *; Arango 1”); Puerto Rico (Krug ”). 
Var. minor. 
Planorbis capillaris, Beck, Index Moll. p. 119 (1837) (sine descr.) ™. 
Planorbis intermedius, Philippi, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limnzaceen, 
p. 39, t. 16. figg. 18, 19 (1850) '* (nec intermedius, Charpentier, 1837). 
Planorbis albescens, Uhde, in litt.* (nec P. albicans, Spix, 1827, nec Pfr. 1839). 
Planorbis tumidus (Pfr.), Kiister, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limneaceen, 
p. 40, t. 9. figg. 1-3; v. Mart. in Malak. Blatt. xii. p. 54 (1865) * (part.) ; Strebel, Beitr. 
Mex. Land- und Siissw.-Conch. i. p. 41 (‘Viele Exemplare,” etc.), t. 5. fig. 20a”. 
Planorbis tumens (Carp.), Fisch. & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 62 (part.), t. 82. 
figg. 4, 4a, b,c”. 
Planorbis intermedius, var. minor, Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, 
Limneiden, p. 197, t. 11. fig. 2”. 
Planorbis guatemalensis, Clessin, loc. cit. p. 209, t. 82. fig. 7 (1889) ?°. 
Of smaller size: diam. maj. 14-154, min. 114-12, alt. 6-62; apert. diam. 53-6, ampl. 6-62 millim. 
Hab. E. Mexico: Vera Cruz (Uhde!® 21; Strebel 22; H6ge), in brackish marshes (Lieb- 
mann 1821); Jalapa (Hége). 
N. Guatemata: Coban (Bocourt *); Guatemala, without nearer indication of locality 
(Morelet ?°). 
