42 COELOCENTRUM. 



knot-like. Crosse & Fischer's figures of the type are copied 

 on my plate 9, figs. 17, 18. Pfeiffer's figures of a form pos- 

 sibly referable to the next species are also given, figs. 19, 20. 

 C. ARCTISPIRA (Pfeiffer). PI. 14, figs. 33-36. 



Shell rimate, cylindric-turreted, Jbroadly truncate, rather 

 solid, closely subarcuate-ribbed, somewhat opaque, whitish- 

 suture deep, subnodulose, whorls remaining 18, narrowly 

 coiled, convex, the last narrower, thread-carinate, shortly pro- 

 tracted forward. Aperture small, oblique, obliquely oval: 

 peristome continuous, glossy, narrowly reflexed throughout, 

 the left margin laterally produced. Length 38, diam. 10 mm. ; 

 oblique length of aperture 6%, width 6 mm. (P/r.). 



Juquila, State of Oaxaca (Boucard, type locality) ; Istapa, 

 State of Tabasco (Salle). Var. estefania at Quilate, Agua 

 Calient e, and Arroyo del Banco, all in the environs of Misantla, 

 V. C. (Dona Estefania Salas). 



Cylindrella arctospira PFR., P. Z. S. 1860, p. 139, pi. 50, f. 2 

 (see below under C. aristispica) . Cylindrella arctispira PFR., 

 Malak. Blatter viii, p. 81 ; Monogr. Hel. Viv. vi, p. 377 ; vii, p. 

 438. SOWERBY, Conch. Icon, xx, pi. 14, f. 123. Ccclocentrum 

 arctispirum C. & F., Moll. Mex. i, p. 348, pi. 15, f. 15. Mar- 

 tens, Biol. Centr. Amer., Moll., p. 271. ?STREBEL, Beitrag iv, 

 p. 58, pi. 6, f. 4 (shell) ; pi. 14, f. 3 (internal axis) ; pi. 11, f. 

 9, 15; pi. 13, f. 10 (anatomy). 



The original description is given above, and the original fig- 

 ure is copied in my fig. 33 of pi. 14. This figure corresponds 

 with the original description neither in size nor the number of 

 whorls given by Pfeiffer, and therefore does not represent the 

 type specimen. In size, the figure given by Sowerby (pi. 14, 

 fig. 34) comes near Pfeiffer 's measurements, though a little 

 larger, and it has the same number of whorls. Probably it is 

 the type. This figure, however, shows a strongly ribbed shell 

 unlike the forms figured by Crosse & Fischer and by Strebel. 



C. arctispira as identified by Fischer and Crosse, from spec- 

 imens collected by Salle at Istapa, State of Tabasco (pi. 14, 

 figs. 35, 36), measures, length 36, diam. 10 mm., apert. with 

 perist. 6 mm. long, 5 wide; whorls 17. It is quite solid but 

 sufficiently translucent to show the internal column indis- 



