THE NAUTILUS. 139 



Messrs. G. F. and B. H. King, who take great interest in natural 

 history, and who are about to engage upon a thorough exploration of 

 S. W. Ga. and W. Fla. in the interest of science. Their address is 

 Mimsville, Ga. 



NOTES ON SOME SOUTHERN MEXICAN SHELLS. 



BY HENRY A. PILSBRY. 



A small collection of shells from the state of Tabasco, Mexico, re- 

 ceived from Prof. Jose N. Rovirosa, is interesting as supplying a 

 new species of the genus Chondropoma, a genus common to southern 

 Mexico and the West Indies, but far more fully developed in the 

 latter region. 



A new Unio of the Lampsilis group also occurred. The following 

 is a list of the species : 



Polygyru Tucatanea Mor. var. helictomphala Plr. San Juan Bau- 

 tista. 



Thysanophora conspurcatella Morel. San Juan Bautista. 



Oxystyla princeps Brod. 



Subulina trochlea (Pfr.). San Juan Bautista. 



Opeas micro (Orb.). San Juan Bautista. 



Glandina Ghiesbrechti Pfr. 



Succinea Guatemalensis Morel. 



Planorbis tenuis Phil.? (Young.) 



Planorbida obstructa Morel. Margin of the Grijaloa R. 



Aplexa aurantia Cpr. Macajuca. 



Aplexa Tapanensis Cr. & Fisch. San Juan Bautista. 



Chondropoma Martensianum Pilsbry. Montanas de Poana. See 

 below. 



Helicina Virata Pfr. Garden of the Juarez Institute, San Juan 

 Bautista. 



Neritina virginea L. Pueblo " La Ceiba." 



Pachychilus vidneratus Crosse & Fischer. Upper Puyacatengo R. 

 near Teapa. This is the form referred by Morelet (in coll.) to P. 

 Helleri, and made by Crosse & Fischer a variety of P. chrysalis 

 Brot., under the above name. The form seems to offer considerable 

 differences from P. chrysalis, typical specimens of which were col- 

 lected by Sr. Rovirosa at Ixtacomitan, Chiapas, and it may prove 

 specifically independent. The specimens are old, more truncated 



