THE CYOLOPHORID LAND MOLLTJSKS OF AMEEIOA 177 



more than one-fourth of the diameter of the shell and marked by 

 fine incremental lines and on the first half by feeble suggestions of 

 spiral threads. No spiral threads appear on the rest of the umbilical 

 wall. Here the incremental lines are concentrated to form axial 

 riblets. Aperture circular; peristome simple, very slightly expanded; 

 the outer lip projects materially beyond its junction with the columel- 

 lar wall at the posterior angle, forming here a conspicuous shelf. 

 It also is decidedly protracted at that point beyond the columellar 

 lip. Operculum typically barbacyclid. 



The specimen described and figured, U.S.N.M. No. 161616, comes 

 from Costa Kica. It has 6 whorls and measures : Height, 31.5 mm. ; 

 greater diameter, 44.8 mm. ; lesser diameter, 31.6 mm. 



U.S.N.M. No. 321046 contains another specimen also from Costa 

 Kica, without definite locality. 



This species is nearest related to B. houcardi (Angas), from which 

 its much larger size readily distinguishes it. 



BARBACYCLUS BOUCARDI (Angas) 

 Plate 23, Figiibes 4-6 



1878. Cyclotus loucardi Angas, Proc. Zool. Soc. London, 1878, p. 73, pi. 5, figs. 

 3, 4. 



1890. Cyclotus (?) Boucardi v. Martens (in part), Biologia Centrali-Ameri- 

 cana, p. 5. 



1897. Neocyclotus (Neocyclotus) boucardi Kobext and Mollendoktf, Nachrb. 

 deutschen malak. Ges., vol. 29, p. 137. 



1935. Aperostoma princeps angasianum Pilsbry, Proc. Acad. Nat. Sci. Philadel- 

 phia, vol. 87, p. 3. 



Shell helicoid, chestnut-brown on the upper surface, with a mod- 

 erately broad band of white at the summit and at the periphery. 

 There is a zone of the same chestnut-brown immediately below the 

 periphery, while the rest of the base is straw colored. Nuclear whorls 

 about 2, well rounded, smooth. The succeeding turns, except the last 

 portion of the last whorl, are marked by decidedly retractively 

 curved threads, which are about as wide as the spaces that separate 

 them. In addition to this they are also crossed by numerous closely 

 spaced, hairlike incremental lines. Suture impressed, on the last 

 turn marked by a slender, slitlike sinus. The last whorl is decidedly 

 decurrent and solute for about one-tenth of a turn. Periphery well 

 rounded. Base well rounded, marked by incremental lines and near 

 the periphery by obsolete threads. Umbilicus rather narrow, equal- 

 ing about one-fifth of the diameter of the shell. Aperture broadly 

 oval, the long axis being from the parietal wall to the junction of 

 the outer and basal lip; peristome simple, the outer lip extends be- 

 yond its junction with the columellar wall as a shelf. It also is 

 protracted beyond it. Operculum typical. 



