48 MOLLUSCA. 
B. Marginate: elongate; suture marked by a well-limited bandlet ; 
size rather large . . . . . . . . . . ss ss . fusiformis, ghiesbreghti, 
decussata, tenella, cumingi, carmenensis. 
C. Turrite: elongate ; aperture rather short; size variable. . . liebmanni, audebardi, 
isabellina, longula, pinicola, turris, mazatlanica, 
pseudoturris, anomala, simplex, conularis, 
excavata, largillierti, multispira, oblonga, bellula. 
D. Lanceolate : elongate, but the ast whorl more convex; generally 
intensely coloured . . . . . . . .. Cdanceolata, aurantiaca, 
decidua. 
E. Biconice: spire shorter, tapering; last whorl swollen; pale 
coloured, with distinct varices ; outer margin of the aperture 
often angularly produced ; size moderate. . . . . . . cordovana, delicatula, 
conferta, speciosa, ambigua, ? tortillana. 
F. Turgide: ovate, apex rather obtuse ; size moderate or small . orizabe, turgida, filosa, 
fischeri, sulcifera, albersi, mitriformis, monilifera, 
obtusa, stigmatica, nana. 
G. Difficiles: columella distinctly twisted . . . . . . . . diffcilis. 
G. striata and G. plicatula will find their place in the subdivision B, Marginate ; 
G. truncata may be placed either in C, Turrite, or in F, Turgide, the variety parallela 
agreeing better with the former, the var. dudlata with the latter. 
It must be agreed that these groups run very much one into the other, and that it is 
very difficult, or almost impossible, to characterize them more precisely, but they will 
perhaps help somewhat to determine single species. 
The peculiar features of the living animal were first described by Say in 1831, the 
anatomical characters by Raymond and Ad. Schmidt in 1853. The known species were 
first enumerated as forming a distinct subdivision by Férussac in 1821, and then asa 
genus by Morelet in 1852; whereas Bolten and Montfort, and even Schumacher himself, 
founded their genera only on one species, and that an aberrant one (G. glans, Brug.). 
The geographical distribution of the genus Glandina is predominantly Central- 
American, the majority of the species, including the largest; being found there. A few 
species, nearly allied, inhabit the northern part of South America, one only, G. striata, 
extending to the southern half of that continent; in the southern states of North 
America three species are found, G. truncata (with several varieties), G. corneola, and 
G. texasiana. 
The West-Indian Islands have a number of species, which differ more or less consi- 
derably from the continental ones; they belong to distinct subgenera, as Varicella and 
Oleacina sensu stricto. 
Within the limits of Mexico and Central America they are almost equally numerous 
and well deveioped on the Atlantic slope of Mexico proper (EK. Mexico) and in 
Guatemala, the two provinces which have been most diligently and successfully 
investigated; the species of both these districts are partly the same, partly not very 
different from one another. G. sowerbyana extends, so far as we know, from the State 
