114 THE NAUTILUS. 



genus. A few tiny brooks are teeming with fresh-water shells, and 

 the town has the following species: compression, variabile, abditum, 

 ventricosum., ferrugineum succineum, tieglectum, aequilaterale, ferru- 

 gineum and splendidutum, " for the first time seen in large numbers 

 from Massachusetts." A few forms not quite settled may show more 

 of interest. A more careful search next summer may yield even 

 more species from this interesting locality. 



NOTES ON SHELLS COLLECTED AT BALSAS, GUERRERO, MEXICO, BY 

 MR. WALTER E. KOCH, IN DEC., 1908. 



BY H. A. PILSBRY AND GEO. H. CLAPP. 



These shells were found in the crevices of the limestone rocks 

 bordering the Rio Balsas, and the ravines leading to it, and about 

 1000 feet above the river, or at an altitude of 2000-3000 feet. No 

 living shells were seen, and limited time prevented a very thorough 

 search. 



EUGLANDINA LIEBMANNI (Pfr.). 



The specimens have the more minute sculpture very beautifully 

 developed, agreeing with Strebel's account of the type specimen. 

 There is also a coarser form in some other localities, which seems to 

 be more abundant in collections. 



POLYGYRA MATERMONTANA Pils. 



A series of eleven specimens shows great variation in size and 

 shape of the umbilicus, and better preserved examples might possibly 

 show the presence of more than one species in the lot. The extremes 

 in size are 7.3 mm. diam. with 5 whorls, and 11 mm. with 5^ whorls. 



OXYSTYLA ZONIFERA (Strebel). 



Typical examples of this well-marked species. 



HOLOSPIRA BARTSCHI I). Sp. PI. Vlii, figs. 5, 6. 



The shell is white, imperforate, oblong, widest at the eighth or 

 ninth whorl, rapidly tapering to the last whorl; terminal cone short, 

 the apex mamillar. Two embryonic whorls smooth, gray, project- 

 ing, the first whorl wider than the second; following three whorls 



