144 BULLiETEN 181, UjSTITED STATES NATTONlAiL MUSEUM 



The United States National Museum collections contain the follow- 

 ing specimens: U.S.N.M. No. 32069, 3 from Guatemala; U.S.N.M. No. 

 251126, 1 collected by O. F. Cook at Alta Vera Paz, Guatemala; 

 U.S.N.M. No. 321031, 2 collected by S. Smith in Guatemala; U.S.N.M. 

 No. 57333, 3 received from Bland, collected in Guatemala; U.S.N.M. 

 No. 104444, 1 from Alta Vera Paz, Guatemala ; U.S.N.M. No. 316386, 

 2 from Guatemala ; U.S.N.M. No. 321033, 1 collected by Salle, labeled 

 "Mexico." 



In size this species resembles T. simulacrum,^ from which it is easily 

 distinguished by its rather strong axial ribs, which are absent in 

 nTnulacrum. 



TOMOCYCLUS GUATEMALENSIS (Pfeiffer) 

 Plate 19, Figure 4 



1851. Cyclostoma guatemalense Pfeiffer, Proc. Zool. Soc. London, 1831, p. 245. 



1852. Megalomastoma guatemalense Pfeeffee, Monographia pneumonopomorum 



viventium, vol. 1, p. 132. 



1853. Cyclostoma guatemalense Pfeiffek, Martini-Chemnitz Conchylien Cabinet, 



vol. 1, sect. 19, p. 267, pi. 36, figs. 13, 14. 

 1872. Tomocyclus guatemalense Crosse and Fischee, Journ. Conchyl., vol. 20, 



p. 76. 

 1878. Megalomastoma guatemalense Reeve, Conchologia iconica, vol. 20, pi. 8, 



fig. 73. 

 1886. Tomocyclus guatemalensis Fischee and Crosse, Mission scientifique au 



Mexique et dans I'Am^rique centrale, vol. 2, pt. 7, p. 124, pi. 40, fig. 11. 



We have not seen specimens of this species and copy Pfeiffer's 

 figures and translate his description as given in Martini-Chemnitz. 



Shell perforate, elongate, rather thick shelled, moderately truncated 

 above, axially finely striate, white beneath a greenish-brown perios- 

 tracum. Spire with a somewhat convex outline, gradually tapering. 

 Whorls 6, slightly arched, the last shorter, descending anteriorly, and 

 somewhat solute, compressed about the narrow open umbilicus but 

 not keeled. Aperture parallel with the axis, almost circular. Peri- 

 stome free, white, double, the inner complete, and only slightly pro- 

 duced; the outer expanded at right angles to the aperture, excised 

 over the perforation. Length, 24 mm. ; diameter, 8 mm. 



Pfeiffer's figure has 5.8 whorls remaining and measures: Height, 

 23.2 mm.; greater diameter, 11.6 mm.; lesser diameter, 8.2 mm. 

 Height of aperture externally, 8.2 mm., internally, 6.1 mm. ; diameter 

 externally, 6.7 mm., internally, 5.1 mm. 



Habitat: Alta Vera Paz, Guatemala. 



These figures show a finely ribbed shell with a much more narrowly 

 expanded outer peristome than in any of the other species. 



