XANTHONYX. 343 
XANTHONYX. 
Simpulopsis, Pfeiffer, Monogr. Helic. Vivent. iv. p- 799 (part.). 
Xanthonyz, a & Fischer, Journ. de Conch. xv. p. 223 (1867) ; Miss. Scient. Mex., Mollusca, 
i. p. 192. 
Shell external, very thin, with few rapidly increasing whorls and short spire, 
imperforate ; aperture wide, rounded, thin-edged. Jaw strongly ribbed; teeth of the 
radula subquadrate, median tooth tricuspid, laterals with two cusps. The shell may be 
distinguished from that of Simpulopsis (antea, p. 252) by the depressed form, flat top, 
and very wide aperture. 
Confined to Mexico, so far as at present known. 
Comparative TABLE OF THE SPECIES oF XVanrHonry. 
Nomen. Forma. Seulptura. Coloratio. Apertura. Long. | Diam. ee Patria. 
mm, mm. mm. 
salleanus, Pfr. ...... subsemiovata, striatula, nitida, | corneo-straminea. | “lunato-rotunda-| 14 7 ll | E.&S8. Central 
solidula. lineis_ spir. im- ta,” intusmar-| 15 Te]... Mexico. 
pressis obsoletis, garitacea, marg. 
testa embr. le- colum. tenui. 
viuscula, 
cordovanus, Pfr. ...| subsemiglobosa, | minute striatula, | virenti-cornea. marg. colum. la~| 15 7 10 | E. Mexico. 
tenuis. lineis spir. im- tiusculo. 
pressis, testa 
embr. costulata. 
sumichrasti, Brot... 
oblongo - semi- | leviter striatula, | fusculo-cornea. ” 12 63 8 | Mexico. 
ovata, tenuis. nitidissima. 
chiapensis, Pfr. ...| depresse globosa, | confertius striata, | cornea, pellucida. lunato-circularis, | 84 44 S.E. Mexico. 
tenuissima. nitida. marg. externo 
superne sub- 
recedente. 
1. Xanthonyx salleanus. 
Simpulopsis salleana, Pfr. P. Z. S. 1856, p. 319, t. 25. figg. 15, 16°; Monogr. Helic. Vivent. iv. 
p. 8017; Binney, Proc. Acad. Phil. 1860, p. 151°; Reeve, Conch. Icon. xiii., Simpulopsis, 
t. 2. fig. 9%. 
Xanthonyzx salleanus (Pfr.), Crosse & Fisch. Journ. de Conch. xv. p. 225 (1867)°; Miss. Scient. 
Mex., Mollusca, i. p. 199, t. 10. figg. 2,2a°; Strebel, Beitr. Mex. Land- und Stissw.-Conch. 
iv. p. 26, t. 2. figg. 1 a-e, t. 10. fig. 8 (embryonal whorl) ’. 
Hab. EF. Mexico: wood of Pacho, near Jalapa (Salas™); Cordova (Sallé 1~®). 
S. Centra Mexico: Oaxaca (Hoge). 
9. Xanthonyx cordovanus. 
Simpulopsis cordovana, Pfr. P. ZS. 1856, p. 319 *; Monogr. Helic. Vivent. iv. p. 801°; Binney, 
Proc. Acad. Phil. 1860, p. 151°; Reeve, Conch. Icon. xiii., Simpulopsis, t. 2. fig. 10°. 
Xanthonyx cordovanus, Crosse & Fisch. Journ. de Conch. xv. p. 226 (1867)°; Miss. Scient. Mex., 
Mollusca, i. p. 200, t. 10. figg. 3, 3a°; Strebel, Beitr. Mex. Land- und Siissw.-Conch. iv. 
