STROBILOPS, CANADA AND UNITED STATES. 25 



view, penetrating about as deeply as the parietal. There is a 

 quite short and very low interparietal lamella, situated near 

 the inner ends of the others. A third of a whorl within there 

 is a very short, low lamella on the axis and five baso-palatal 

 folds: near the axis two large basal folds, the inner tongue- 

 shaped, the outer one longer ; outside of these there is a minute 

 and low third fold, often wanting, leaving a space ; the fourth 

 and fifth folds long and low (fig. 8). Just above the peri- 

 phery on the outer wall a very weak, low, long sixth fold may 

 often be traced, but in fully adult shells the smaller folds are 

 usually reduced in number (fig. 10), or even wanting (fig. 9) ; 

 the full number described above being rare except in the late 

 neanic stage. 



Height 2, diam. 2.4 mm. Type. 



Height 2, diam. 2.3 mm. Alexandria, La. 



Texas : drift of the Guadalupe river about four miles above 

 New Braunfels (type loc. ; Pilsbry and Ferriss, 1903) ; Austin 

 (Pilsbry) ; San Marcos (Pilsbry and Ferriss) ; New Braunfels 

 (Ferriss, Pilsbry, and Singley) ; Guadalupe river bottom, Vic- 

 toria county, and Lavaca river, Jackson county (J. D. Mit- 

 chell) ; Lee county (Singley) ; Calhoun county (E. "W. Hub- 

 bard) ; Gainesville (J. B. Quintard) ; Colorado river near 

 Travis, Bastrop Co. (Julia Gardner). A smaller form, diam. 

 2 mm., was taken in drift debris of the Hondo river about two 

 miles north of Hondo, Medina county (Ferriss and Pilsbry). 



Oklahoma: Limestone Gap and Wyandotte (Ferriss and 

 Pilsbry) ; Fort Gibson (B. W. Hubbard) ; Pottawatomie Co. 

 (J. B. Quintard). 



Arkansas: Ashley and Calhoun counties (C. B, Moore). 



Louisiana : Sycamore and Wilson landings, Morehouse Par- 

 ish; Alexandria, Rapides Parish (C. B. Moore). 



Strohilops lahyrmthica texasiana Pilsbry and Ferriss, 

 Proc. A. N. S. Phila. 1906, pp. 147, 557.— Wheeler, Nautilus 

 XXXI, p. 114 (Arkadelphia, Ark.). — Strecker, Naut. XXII, 

 p. 65 (McLennan Co., Tex.). 



This form differs from the closely related 8. lahyrinthica by 

 the stronger, more spaced ribs, continued over the base, and 

 by the more deeply penetrating parietal lamella. 



