236 HULIiETTN ISl, UNITEID STATES MVOOOSnAJL MUSEfUM 



APEROSTOMA (APEROSTOMA) IRREGULARE (PfeifEer) 

 Plate 33, Figtjke 4 



3855. Cyclostoma (Cyclotus) irregnlare PFEaFFER, Proc. Zool. Soc. London, vol. 23, 

 p. 117. 



1858. Cyclotus irregularis PFEiFFEa?, Monographia pneumonopomorum viventiuin, 

 vol. 2, p. 15. 



1864. Cyclotus irregularis Reeve, Conchologia iconica, vol. 14, pi. 4, fig. 18. 



1890. Cyclotus (Aperostoma) irregularis von Mabtens, Biologla Centrali- Amer- 

 icana, Suppl., pp. 3, 596. 



1897. Neocyclotus {Neocyclotus) irregularis Kobelt and Moixendobff, Nachrb. 

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



1923. Poteria (Neocyclotus) irregulare H. B. Baker, Occ. pap., Mus. Zool. Univ. 

 Michigan, No. 137, p. 41. 



As we have not seen this species we give a translation of Pfeiffer's 

 description : 



Shell umbilicated, depressed-turbinate, solid, closely striated, yel- 

 lowish. The spire is shortly turbinate, acute. Suture profound. 

 Whorls 5, convex, the last swollen above and bfoadly canaliculate at 

 the suture ; below marked by a broad median band. The broadly fun- 

 nel-shaped umbilicus is limited on the outside by a strong angulation. 

 Aperture oblique, triangularly oval, angulated above; peristome 

 continuous, slightly adnate to the preceding turn, straight. The right 

 outer lip dilated; columella thickened moderately arcuate, channeled 

 basally. Major diameter, 37 mm. ; lesser, 30 mm. ; altitude, 19 mm. 



Habitat : Central Costa Kica. 



Keeve's figure shows a decided notch at the junction of the inner 

 and basal lip which is responsible for the angulation marking the outer 

 edge of the umbilicus. 



The species appears most nearly related to A. (A.) pittieri (von 

 Martens) but differs from it in being much larger. 



APEROSTOMA (APEROSTOMA) PITTIERI (von Martens) 



1900. Cyclotus (Aperostoma) irregularis pittieri von Martens, Biologia Centrali- 



Americana, Suppl., p. 597. 

 1923. Poteria (Neocyclotus) irregularis pittieri, H. B. Baker, Occ. Pap. Mus. 



Zool. Univ. Michigan, No. 137, p. 41. 



We have not seen this species. Von Martens distinguishes it from 

 A. (A) irregulare Pfeiffer with the following diagnosis, which we 

 translate : 



Distinctly flatter than the typical form [irregularel^ less vaulted, 

 29 mm. only in diameter and 16.5 mm. in height. Aperture 12 mm. 



Habitat: Salinas Bay, northwestern Costa Rica, collected by H. 

 Pittier. 



Tlie much smaller size distinguishes this from A. {A.) irregulare 

 (Pfeiffer). 



