KEY TO UROCOPTIDvE. XXXVU 



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 



