26 ODONTOSTOMIN^E. 



no large vessels, coarse reticulation being confined to the two ends 

 of the lung, (fine transverse venation of the intermediate space being 

 omitted in the figure). In Macrodontes (pi. 15, fig. 29), the lung is 

 short, a modification correlated with the reduced number of whorls 

 of the shell. There is a strong secondary pulmonary vein, and a 

 small tertiary, the cardiac side of the lung having a strong, branch- 

 ing venation, while on the intestinal side the venation is fine, close 

 and mainly transverse. The pattern of lung venation in Macro- 

 dontes is unusual, and I have seen nothing like it elsewhere in the 

 Bvlimulidce. It reminds me of Strophocheilus and the Acavidce. 



The genitalia are exceedingly lengthened in Odontostomus and 

 Anostoma, much less so in Macrodontes. There are no accessories, 

 the whole apparatus being Bulimuline. 



Shell. The heliciform groups of Butimulince, such as Platybostryx 

 and Oxychona, prepare us for shortened shell-contours in the Odont- 

 ostomince. In Tomigerus the modification is not great ; but Anos- 

 toma presents a form so bizarre that in the total absence of informa- 

 tion upon its life history, no useful theory can be formulated to 

 account for its peculiarities. 



The apical sculpture in Odontostommce varies within the same wide 

 limits observed in Bulimulince, and presents nearly identical patterns. 

 In Anostoma, Tomigerus and Anctus the apex is smooth, as in the 

 Bostryx type of Bulimulina. In Macrodontes (pi. 15, fig. 30) it is 

 spirally lirate. In Odontostomus, including the sections Moricandia, 

 Bahiensis (pi. 15, f. 31) and Cyclodontina, it is like that of Dry- 

 maus. In Hyperaidax and 0. (Plagiodontes) dentatus (pi. 15, f. 25) 

 the apex has waved wrinkles as in typical Bulimulus, while in 

 Spixia (pi. 15, fig. 34) and the other species of Plagiodontes (pi. 15, 

 fig. 32) there are straight riblets like those of Orthotomium, Nasiotus. 

 etc. There is an incomplete transition from the Drymcsus type to 

 the Spixia type by the growing predominance of vertical, with 

 gradual loss of spiral sculpture, exemplified in some species. 



The teeth obstructing the apertures of the Odontosto mines are far 

 more stable in position and arrangement than would be thought on 

 first inspection. They may most readily be described by use of the 

 terminology of the similar teeth of Pupida, 



Lamella on the parietal wall: Angular, parietal and infraparietal 

 lamellae. 



Lamella on the columellar margin: Supracolumellar, columellar 

 and sub-columellar lamellae ; basal fold. 



