TKTF^\PI.ODON 1203 



Castalia }iniltis!ilcata Hupe, INIoll. Xouv.. ITT, 1857, p. 75, pi. 



XIV, fig. 4. 

 Tetraplodon multisalcatiis Simpson, Syn.. 1900, p. 865. 

 Castalia initlticostata Sowerisy, Conch. Tcon.. XVTI, 1869, pi. 



II, figs. 9, 90, gb. 

 Castalia ambigiia r.r.AiNViijjc, Man., 1825, p. 539. pi. lxvii, 



fig. 4. 



For a Tctraplodoji this shell is but little inflated. It is cov- 

 ered throughout with somewhat delicate subzigzag, radiating 

 ribs. 



Tetraplodon ecarinatus (Mousson). 



Shell subtriangular, not very solid nor greatly inflated, 

 scarcely inequilateral; beaks only moderately high, sculptured 

 with numerous radiating ridges, which cover the entire shell; 

 these are crossed by concentric threads over the whole surface ; 

 anterior end narrowed and rounded ; base line rounded ; dorsal 

 slope obliquely truncate, angled a little behind the ligament; 

 epidemiis fuscous ;. posterior ridge rather low, subangulate 

 above ; teeth compressed, serrate ; beak cavities deep ; nacre 

 pearly, iridescent. 



Length, 47, height 35, diam. 25 mm. 



Puerto Nuevo, Magdalena River, Colombia. 

 Castalia ecarinata ATousson, Alal. Bl., XVT, i86<>, p. 185. — 



PfeiFPER, Nov. Conch., IV, 1876, p. 140, pi. cxxxi. figs. 9, 10. 

 Tetraplodon ecarinatus Simpson. Syn., 1900, p. 865. 



The beaks in this species are placed only a little in front of 

 the center; the whole surface is strongly sculptured with from 

 22 to 24 radial ribs, which are crossed by strong growth lines. 



Tetraplodon crosseanus (Hidalgo). 



vShell subrhomboid, subsolid, compressed, inequilateral, sculp- 

 tured with numerous, curved, radial costae, the anterior end 

 granular, the posterior end nearly smooth ; beaks rather low ; 

 anterior end widely rounded, cut away a very little below ; base 

 line nearly straight ; post-dorsal outline strongly curved from 

 the beaks to the rather sharp basal point at the termination of 



