104 OXYSTYLA- 



Most authors, however, including Shuttleworth, in his valuable mon- 

 ograph, have treated them as distinct, and I adopt this plan ; but I 

 confess that in some cases it is very difficult to decide to which species 

 a single specimen may belong." The material I have studied fully 

 supports Dr. von Martens' remarks just quoted. It should be added 

 that there are several species of the undata-princeps group, such as 

 obducta and longa, which are readily distinguishable and undoubtedly 

 "good" species, and in fact forms occur of every grade between species 

 and mere local races. There is no particular advantage in lumping 

 them under one name, as the forms are definitely limited geographi- 

 cally, and the knowledge already gained of their variation and dis- 

 tribution would be largely lost by lumping all of them under one or 

 two of the old names. 



The species are herein grouped geographically under (1) Mexican 

 and Central American, (2) species of the Antilles and Florida, and 

 (3) South American. This arrangement separates some closely- 

 allied forms, such as 0. undata, maracaibensis and ferussaci, but is 

 probably more convenient than a strictly natural sequence. 



The oldest description of a species of this genus, Buccinum zebra 

 Miiller, Vermium Terrestrium et Fluviatilium, ii, p. 138 (1774), 

 would apply to various species, but is so vague that it cannot be fixed 

 upon any one of them. As illustrations of his species, Miiller cites 

 numerous figures: Lister, pi. 11, f. 6 = Perideris ; 9, 4 and 10, 5 

 = Limicolaria f ; 580, 34= Orthalicus prince ps f or undatus f young; 

 578, 33 = Achatina fulica ; Petiver, Gazophyl. 44, 7 = a uniform 

 white Oxystyla, possibly 0. maracaibensis f. imitator ; Seba, The- 

 saurus, pi. 39, f. 54, 55 = O.ferussacif and f. 50, 51 = 0. melano- 

 cheilus, tricinctus or imitator. 



The terms of the specific description exclude Achatina. The name 

 practically covers the entire genus Oxystyla, with similarly marked 

 species of Limicolaria ; but in my opinion neither the melon ocheilus- 

 like form selected by Shuttleworth, nor the 0. undatus of Bruguiere 

 can fairly be called zebra ; the first because Muller's name and de- 

 scription point rather to a zebra-striped and not a three-banded shell, 

 the second because undatus was the first species to be segregated from 

 Muller's composite group, and hence has a valid claim to retention. 



There is a specimen in Muller's collection which Morch took for 

 the type, apparently either melanocheilus, tricinctus or imitator / but 

 Miiller states that the type is in Spengler's collection. 



