458 MOLLUSCA. 
Hab. Satvapor: Rio Sucio. 
Two specimens, apparently full-grown, both given me by Dr. O. Stoll; but not 
collected by himself. 
13. Pachychilus panucula. | 
Melania panucula, Morelet, Test. Noviss. ii. p. 23 (1851)*; Brot, in Martini & Chemnitz, Syst. 
Conch.-Cab. ed. 2, Melaniaceen, p. 27, t. 3. figg. 3, 3a, 0”. 
Pachychilus panucula, Fisch. & Crosse, Miss. Scient. Mex., Moll. i. p. 341, t. 53. fige. 8, 8a’. 
Intermediate in form between P. corvinus and P. chrysalis; base of the aperture somewhat produced, 
Hab. S.E. Mexico: State of Chiapas (Parreyss *). 
N. Guatemata: Rivers of the Department of Peten (Morelet1?), especially the 
R. Mopan (Morelet *). 
The specific name is derived from the Latin words panus, panucellium, “a heap of 
wool at the spindle” ; different from pannus, panniculus, “a scrap of cloth.” 
Var. mexicanus. 
Melania mexicana, Reeve, Conch. Icon. xii., Melania, t.18. fig. 129*; Brot, in Martini & Chemnitz, 
Syst. Conch.-Cab. ed. 2, Melaniaceen, p. 45, t. 5. fig. 9 (copy from Reeve) ’. 
Pachychilus mexicanus, Fisch. & Crosse, Miss. Scient. Mex., Moll. i. p. 340°. 
Last whorl more swollen in its basal part, resembling a bag, the columellar margin therefore very oblique. 
Hab. Mexico, without nearer indication of locality °°, probably S.E. Mexico. 
Brot’s figure 9@ has not the characteristic form of this variety, and may belong 
to the typical P. panucula. 
Var. tumidus. (Tab. XXV. fig. 5.) 
Melanoides tumidus, Tristram, P. Z.S. 1863, p. 4137. 
Melania tumida, Brot, loc. cit. p. 23°. 
Pachychilus tumidus, Fisch. & Crosse, loc. cit. p. 857°. 
Very large; upper whorls nearly even, but very convex at the periphery, rapidly narrowed below; base of the 
aperture distinctly produced into an angular lobe. 
a. Long. 65, diam. 32; apert. long. 23, lat. — millim. 
BQ ©6, «= 64, yg, S28 - 254,,, 17 ,, Anfr, superst. 7. 
a. Tristram’s statement; 6. Measurements of the specimen sent to me for examination. 
Hab. N. Guatemata: Lake of Peten (Salvin ‘—®), 
14. Pachychilus orstedi. (Tab. XXVII. figg. 8-5.) 
Pachychilus Grstedii, Morch, in Malak. Blatt. vii. p. 79 (1860) *. 
Melania orstedtii, Brot, Matériaux fam. Mélaniens, iii. p- 29, t. 3. fig. 10°; in Martini & Chemnitz, 
Syst. Conch.-Cab. ed. 2, Melaniaceen, p. 46, t. 5. fig. 10°. 
Melania gassiesi (Reeve), Tate, Amer. Journ. Conch. v. p. 152 (1876) *. 
Pachychilus jansoni, H. Adams, P. Z, 8. 1870, p. 795°; Brot, loc. cit. p. 40°, 
