MACROCERAMUS. 287 
MACROCERAMUS. 
Macroceramus, Lansdown Guilding, Zool. Journ. iv. p. 168 (1828). 
Shell longitudinal, conically or regularly turrite, with many (9-19) gradually increasing 
whorls, all of them remaining in the adult state, the last usually angulate at the base ; 
aperture comparatively small, not produced beyond the suture ; peristome not conti- 
nuous, but interrupted by the penultimate whorl, shortly reflexed. Jaw very thin, 
costate, the coste converging and meeting in an acute angle in the middle. Radula 
with oblique rows of teeth, the median tooth smaller than ‘those next it, rather blunt ; 
lateral teeth with one, the marginals with two little points on the outer side. [ Bland, 
Ann. Lyc. N. York, viii. p. 162, fig. 6 (1867); Crosse, Journ. de Conch. xviii. t. 3. 
figg. 14-16 (1870); Binney, Proc. Acad. Phil. 1875, pp. 223, 251, t. 15. fig. 1 and 
t. 20. fig. 9.] 
This genus is chiefly confined to the West-Indian Islands; a few species, however, 
closely resembling the West-Indian forms, are found on the mainland of Florida, 
Mexico, Guatemala, and Honduras, 
1. Macroceramus concisus. 
Cylindrella concisa, Morelet, Test. Noviss. i. p. 12 (1849) *, and ii. p. 27 (1851) *; Deshayes, in 
Férussac’s Hist. Nat. Moll. Terr. ii. p. 224, t. 164. figg. 23-25 °. 
Macroceramus concisus, Petit, Journ. de Conch. i. p. 379 (1850) *; Fisch. & Crosse, Miss. Scient. 
Mex., Mollusca, i. p. 421, t. 18. figg. 1, la, 6°; Pfr. Monogr. Helic. Vivent. viii. p. 420°; 
Strebel, Beitr. Mex. Land- und Siissw.-Conch. iv. p. 90, t. 5. fig. 4.¢7. 
Macroceramus polystreptus, Tristram, P. Z. S. 1861, p. 233, t. 26. fig. 11°; Pfr. Monogr. Helic. 
Vivent. vi. p. 845°. 
Hab. Yucatan (Morelet 12°), Merida (Hége). 
N. Guatemata: Peten, on rocky hills (Morelet +>); Coban * (Sarg7, Salvin ® °). 
The number of costule in the penultimate whorl is somewhat variable—49, 50, and 
54, in specimens from Guatemala and Yucatan; Strebel’ also gives 00. 
Var. meaicanus,n, (Tab. XVII. fig. 2.) 
Macroceramus pontificus, Strebel, loc. cit. p. 89, t. 5. fig. 4.d (nec A. Gould) ”. 
Relatively shorter and broader, length 84-94 millim., diameter of the Jast whorl 3-33 millim.; 93-9? whorls 
only ; white papille at the suture small, scattered, and few in number ; peristome of the aperture.rather 
thin. Number of costule 60 or more, according to Strebel”; some of them, however, are so indistinct 
that it is very difficult to count them. 
Hab. E. Muxtco: Orizaba (Berendt, Botteri }°, Hége); Atoyac (H. H. Smith); Arroyo 
grande, near Misantla (Sa/as?°). 
CentraL Maxico: Sayula, in the State of Jalisco, one specimen, not full-grown 
(Hoge). 
* The locality is incorrectly given as Duefias by Fischer and Crosse. 
