156 BULLETIQSr 181, UNITE© STATElS NlAOOiNiAL MUSlEfUM 



L. haematomma is nearest related to L. antoni (Cousin), from 

 which its finer, irregular spiral threads readily distinguish it. 



LAGOCYCLUS CROSSEANUS (Hidalgo) 

 Plate 20, Figures 9-11 



1866. Cyclophorus crosseanus Hidalgo, Journ. Conchyl., vol. 14, p. 343, pi. 14, 



fig. 1. 

 1897. Amphicyclotus crosseanus Kobelt, Nachrb. deutschen malak. Ges., vol. 29, 



p. 139. 



Shell of helicoid outline, covered with an olive-brown periostracum, 

 white when this is removed, the basal portion being considerably 

 darker than the spire. There is also a subperipheral chestnut-brown 

 band present, which gradually fades toward the base. The nucleus 

 consists of about one turn and is smooth. The postnuclear whorls are 

 marked by spiral cords, of which 7 are present on the first and second, 

 8 on the third, and 12 on the last whorl between the summit and the 

 periphery. These cords are a little less strong near the summit and 

 stronger at the periphery. In addition to this the spire is marked 

 by fine incremental lines. Suture strongly impressed. Periphery 

 rendered angulated by a spiral cord. Base strongly rounded and 

 marked by incremental lines only. There is a strong spiral keel at 

 the outer edge of the umbilicus, w^hich terminates in a notch at the 

 peristome. Umbilicus moderately broadly openly umbilicated, its 

 wall marked by almost riblike incremental lines. Aperture slightly 

 oblique, circular ; peristome simple, except the notch referred to above ; 

 parietal wall covered with a thin callus. Operculum corneous. 



The specimen described and figured, U.S.N.M. No. 307412, was re- 

 ceived from Sowerby and Fulton with the locality label "Ecuador." 

 It has 5.2 whorls and measures : Height, 14.7 mm. ; greater diameter, 

 22.5 mm. ; lesser diameter, 17.0 mm. 



This species is readily distinguished from L. antoni (Cousin) by 

 lacking the spiral threads on the posterior base. 



LAGOCYCLUS VASCONESI (Jousseaume) 



Plate 20, Figubes 12-14 



1897. Cyclophorus vesconesi Joitsseaumb, Le Naturaliste, vol. 19, p. 250. 



1898. Cyclophorus vasconesi Jousseaume, Le Naturaliste, vol. 20, p. 81 (cor- 



rection). 



1899. Amphicyclotus vesconesi Kobelt and Mollendokff, Nachrb. deutschen 



malak. Ges., vol. 31, p. 136. 



Shell of helicoid outline, covered with a chestnut-brown periostra- 

 cum on the later turns; the early turns are reddish. It is a little 

 paler on the underside than on the spire, and there is a light zone at 

 the periphery bordered by a moderately broad dark band anterior to 



