PACHYCHILUS. 459 
Near e chrysalis and-P. panucula, but with the penultimate whorl not so large as in the former and the last 
whorl somewhat more convex than in the latter ; columellar margin strongly arched. . 
Hab. | E. NicaRacua: Segovia ((rsted 1~3) ; Matagalpa, in the Arroyo Alasan (Rothschuh, 
on Mus. Berol.) ; Chontales (Janson ®*) ; on stones in the rocky beds of the clear, 
rapid-flowing streams taking their rise in the Chontales Mountains (Tate +). 
The editors of this work have sent me some specimens of the same species labelled 
as having been probably collected in Costa Rica by Mr. Rogers. 
These shells, like others from Matagalpa, are generally a little more ventricose than 
the figures given by Brot 2 3, and they also differ in this respect from the measurements 
given by H. Adams®. I have not seen any of Tate’s examples, and he gives no 
description ; but as Reeve’s figure of M. gassiesi (not that of Brot and Fischer and 
Crosse) is rather near P. 6rstedi, and the locality coincides so well, I think it is quite 
probable that they belong to this species. 
Var. planensis. 
Melania planensis, Lea, Proc. Acad. Phil. x. p. 118 (1858)7; Obs. Unionidae, xi. p. 83, t. 22. fig. 26 
(1864) *; Brot, loc. cit. p. 33, t. 4. fig. 3°. 
Very large and somewhat more cylindrical. Long. 56, diam. 23; apert. long. 23 millim. 
Hab. Honpvuras: Plan and Omoa, valley of the Ulua River, Atlantic slope (Le Conte™~). 
A shell found by Dr. O. Stoll in the Sierra del Mico, near Yzabal, Eastern 
Guatemala, long. 43, diam. 194, apert. 194 millim., remaining whorls 5, probably 
belongs to this variety. 
15. Pachychilus cinereus. 
Melania cinerea, Morelet, Test. Noviss. i. p. 26 (1849) '; Reeve, Conch. Icon. xii., Melania, t. 35. 
fig. 2357; Brot, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Melaniaceen, p. 38, t. 4. 
fig. 6°. 
Pachychilus cinereus, Fisch. & Crosse, Miss. Scient. Mex., Moll. 11. p. 334, t. 52. figg. 8, 8a-c’*. 
Hab. N. Guatemata: in the river of Coban, Alta Vera Paz (Morelet1~*, Bocourt *). 
H. v. Ihering (in litt.) states that P. cinereus is a local variety of P. indiorum ; I 
have not seen a specimen of it. 
16. Pachychilus explicatus. 
Pachychilus indifferens, var. eaplicata, Fisch. & Crosse, Miss. Scient. Mex., Moll. it. p. 337, t. 53. 
figg. 9, 9a (10, 10a)’. 
Hab. N. Guaremata: Rio Machaquila, Department of Peten (Morelet +). 
The two examples figured by Fischer and Crosse seem to differ greatly inter se. Fig. 9 
has a strongly arcuated columellar margin, without basal projection ; it may represent 
58* 
