KEY TO UROCOPTIDjE. XXXV11 



3. Axis with a sub-basal cord or lamella in the last whorl 

 or two only. Anisospira, xv, pp. 24, 299. 



*** Axis A SOLID, IMPERFORATE COLUMN, whether thick or 

 slender. (Chiefly Antillean; the species of the mainland are 

 all small, and either have the base strongly carinate or the 

 apex entire.) 



I. Axis encircled by a single, strongly projecting lamella, 

 submedian in each whorl. 



1. Peristome interrupted above; spire entire, the proto- 

 conch costulate. Spiroceramus, xvi, p. 172. 



2. Peristome entire; spire normally truncate. 



a. Spiral lamella with the edge smooth; base of the 

 shell carinate. Arangia, xv, p. 162. 



6. Spiral lamella stout, with rounded, closely crenulate 

 edge ; last whorl rounded beneath. Maceo, xv, p. 173. 



II. Axis encircled by two subequal lamella, both serrate or 

 crenulate at the edges; base of shell carinate. 



" Amphicosmia, xvi, p. 49. 



III. Axis with one or more spiral lamellae, the lower one 

 serrate or spinose at the edge, at least in some of the 

 upper whorls; base of the shell usually rounded. 



Gongylostoma, etc., xv, p. 182. 



IV. Lower half or more of the axis thickened; cylindric, 

 twisted, biplicate or nodose. 



1. Shell rather large and stout, red, purple or brown, 

 finely and evenly striate; axis thickened in the lower 

 whorls, with a low, obtuse plait. Jamaica. 



Spirocoptis, xv, p. 113. 



2. Shell stout, barrel-shaped or cylindric, ribbed; axis 

 thick, with two low, smooth cords. Santo Domingo. 



Strophina, xvi, p. 55. 



3. Shell pillar-shaped, white, finely striate; axis cylin- 

 dric, biplicate or nodose-hooked. Jamaica. 



Mychostoma, xvi, p. 96. 



4. Shell smooth or coarsely ribbed, corneous or brown; 

 axis armed with pairs of hooks or flat nodes, or begirt 



