Occasional Papers of the Museum of Zoology 7 



land lores'^s (H, i, a). They were associated with Strcptostyla 

 irriyua similis. Von Martens' (1891) diagnoses this species 

 as "lacvis," l)Ut his figure shows the pHcatulations, and Pfeif- 

 fer's description (1859) distinctly calls attention to them. My 

 specimens show quite definite growth-wrinkles, bounded 

 toward the aperture by impressed lines, which extend up to 

 within 2 whorls of the apex. Traces of very obscure, spiral 

 striations are also visible on the body whorls. The apical 

 whorls are practically smooth, even under considerable mag- 

 nification. The color of the shells is whitish-horn. They are 

 rather small ; the largest have 5 whorls and measure : 



This species has the shortest spire in the genus, and also 

 has the least-shouldered whorls. Nearest it, in general shape, 

 are S. guatcmalensis and S. pulchella, which differ from it by 

 their somewhat higher spires, more marked sutures, and the 

 flatter, vertical sides of their apical whorls. 



S. broicni Pilsbry from Panama, S. guatcmalensis Pilsbry 

 from Guatemala, S. pulchella (Pfeififer) from Chiapas, S. joa- 

 quincT Strebel from Vera Cruz, and S. hinkleyi Pilsbry from 

 San Luis Potosi, form a series of apparently quite closely 

 related species. As a group, they decrease in size quite regu- 

 larly from south to north (lengths 12, 9.9, 10.5, 8.5, 8.5 mm. 

 in the order named), while the spire increases in comparative 

 prominence both north and south of the area near the southern 

 boundary of ]\Iexico (length of aperture divided by length of 

 shell equals 60, 66, 67, 60, 50 per cent, respectively, in the order 

 named). The proportion . between the greatest diameter and 

 the altitude is quite the same (35 to 37 per cent) in all of 



