00 THE NAUTILUS. 



Brazilian and Mexican species, and by the kindness of Professor 

 Gwatkin, of Cambridge, England, who supplied a mounted prepa- 

 ration, I was enabled to figure the jaw and teeth of Helix bifasci- 

 ata, the type of Oxychona, and up to this time, the only species of 

 the group to be dissected. At that time I called attention to the 

 resemblance in dentition between Oxychona, Papuina, Polymita and 

 other arboreal Helices, ending with an allusion to the teeth of 

 Otostomus (now known as Drymceus aurisleporis). Recently while 

 studying the aurisleporis group of Bulimi, I was again struck with 

 the extreme resemblance of their radulse to that of Oxychona. Now, 

 since my former examination of Oxychona, the study of Bulimulid 

 groups has been revolutionized by the discovery of extremely char- 

 acteristic generic and subgeneric characters in the sculpture of the 

 nepionic shell, as the part formed within the egg is called ; so that 



1 at once examined the apex of the Oxychona. The lens revealed in 

 H. bifasciata and the other Brazilian species, the minutely " grated " 

 sculpture of Drymceus ! This combination of the very characteristic 

 and peculiar nepionic sculpture of Drymceus* with the equally char- 

 acteristic dentition, conclusively show that Oxychona is a Drymceus 

 masquerading as a Helix. The Central American and Mexican 

 species referred to Oxychona have smooth apices, very different from 

 the Brazilian group. There can be little doubt that these are true 

 Helicidre ; and as they must now be cut adrift from Oxychona, I 

 propose to reinstate for their reception the group name Leptarionta 

 Crosse & Fischer, based upon Helix bicincta Pfr. This will stand as 

 a genus, and may still be left in my group Belogona euadenia (dart 

 bearers with true glands), next to Lysinoe, until more is known of 

 the soft parts. At least one of the species, L. trigonostoma, is known 

 to have a serrate keel on the tail like Lysinoe. 



Figures of the apices of Oxychona and its Bulimulid allies may 

 be found in the current volume of the Manual of Conchology. The 

 evidence supplied by Semper, Hedley and myself that true Helices 

 often appear disguised as Bulimi, now finds its counterpart in the 

 Bulimulidce, in such Helicoid species as Bulimulus eremothauma 

 Pils., and that worst cheat of all, Drymceus (Oxychona) bifasciatns 

 Burrow. 



4 Drymxus includes not only the Aurisleporis group and the flaring lipped 

 Bulimuli like serperastus, but also "Bulimulus" dormani and multilineatus 

 among Floridian species, either of which, if unworn, will show the apical 

 sculpture alluded to under a sufficiently strong lens. See NAUTILUS, IX p. 114. 



