448 MOLLUSCA. 
Hab. E. Guaremata: Lake of Yzabal and neighbouring streams (Morelet or Bocourt °) ; 
near the town of Yzabal, on the banks of the same lake (Sto//). 
This form is very near P. obeliscus, var. pyrgiscus, Fisch. & Cr., but differs from it in 
having deeper sutures, more convex whorls, and less distinct vertical plaits, especially 
in the last whorl. Stoll’s specimen is extremely like it. 
c. Var. conradti,n. (Tab. XXYV. figg. 9, 10.) 
Vertical plaits undeveloped; spiral ridges well developed, one a little more prominent and slightly nodose. 
Shell moderate in size. 
Long. 54, diam. 20; apert. long. 19 millim. Whorls 73 (Conradt). 
» 00, 4 183; » 163 ,, Whorls 73 (Stoll). 
Hab. E. Guaremata: Panzos (Conradt, in Mus. Berol.); Lake of Yzabal (Stol/). 
d. Var. pumilus. 
Pachychilus lacustris, var. 8. pumila, Fisch. & Crosse, loc. cit. p. 860, t. 51. figg. 4, 4a °. 
Vertical plaits undeveloped; spiral ridges moderately developed, few in number. Shell small. Long. 28, 
diam. 11; apert. long. 10 millim. 
Hab. %.. Guaremata: Lake of Yzabal or neighbouring streams (Morelet or Bocourt ®) ; 
Panzos (Conradt, in Mus. Berol.). 
e. Var. major. (Tab, XXV. fig. 8.) 
Melania lacustris, Hanley, Conch. Miscell., Melania, t. 3. fig. 26°. 
Melania lacustris, var. «, Brot, loc. cit. p. 26, t. 3. fig. 2a’. 
Pachychilus lacustris, var. 8. major, Fisch. & Crosse, loc. cit. p. 360°. 
Vertical plaits undeveloped; spiral ridges rather feeble, equal, sometimes slightly nodose. Long. 57-62, 
diam. 17-19; apert. long. 10 millim. 
Hab. E. Guatemata: Lake of Yzabal (Morelet, Stol/). 
f. Var. terebrals. 
? Melania murrea (Reeve), Brot, loc. cit. p. 30 (part.), t. 3. fig. 7a" 
Pachychilus lacustris, var. n. terebralis, Fisch. & Crosse, loc. cit. p. 360, t. 52. fig. 8a". 
Very elongate, turrite ; vertical plaits undeveloped ; spiral ridges feeble, more distinct on the last whorl only. 
Long. 62, diam. 174; apert. long. 163 millim. 
Hab. E. Guatemata: Lake of Yzabal or neighbouring streams (Morelet or Bocourt 1). 
g. Var. elimatus. 
? Melania subcarinata, Gray in Griffith’s Anim. Kingd. xii. t. 14 (ad p. 487). fig. 7 (1834) ” 
Melania lacustris, var. y, Brot, ioc. cit. p. 26, t. 3. fig. 2¢” 
Pachychilus lacustris, var. ¢. elimata, Fisch. & Crosse, loc. cit. p. 860 '*, 
Subcylindrical; vertical plaits undeveloped; spiral ridges obsolete, almost wanting, save at the base of the 
last whorl. Long. 44, diam. 15; apert. long. 144 millim, 
Hab. HK. Guatemata: Panzos (Conradt, in Mus. Berol.). 
