North American Species of Zonites, etc. 361 



of Mesodon, though somewhat like a gigantic M. Mitchelliana. 



The jaw has 16 ribs. 



The lingual membrane (pi. XIV, fig. F) is long and narrow : 

 teeth 64-1-64, with about 15 perfect laterals on either side of 

 the central line. The central and lateral teeth have no side cusps 

 or cutting points, and only on the extreme marginals does a side 

 cutting point appear. The cutting point of the marginals is long. 

 Thus the dentition is like that of clausa and thy ro ides. 



The genitalia are figured on pi. XIV, fig. E. The genital 

 bladder (g. h. ) is large, oval, on a short, narrow duct : the penis- 

 sac (p. s.) is long and stout, with a sub-central constriction : the 

 prostate gland (pr. ) is highly developed. 



Helix (Dorcasia?) globulus, Mull. 



Cape Town, South Africa, Mr. J. S. Gibbons. 



Jaw low, wide, scarcely arcuate, ends not acuminated : no 

 anterior ribs. 



Lingual membrane wide, with about 40-1-40 teeth. Laterals 

 as well as centrals tricuspid. PI. XIV, fig. K, gives a central, 

 with its adjacent lateral and several inner marginal teeth. 



Both jaw and lingual membrane are quite different from those 

 hitherto observed in Dorcasia, to which sub-genus Von Martens 

 refers the species. 



Mr. Gibbons informs me that the eggs of this species are of 

 very large size. It lives on sandy flats close to the sea margin, 

 burying itself in the sand by day. 



Helix (Fella) rariplicata, Benson. 



Cape Town, South Africa, Mr. J. S. Gibbons. 



The jaw has ribs like those figured for Microphysa Lansingi, 

 in Terr. Moll. U. S., V, — i. e., flat, crowded, wide, numerous. 



The lingual membrane is long and narrow. There are about 

 16-1-16 teeth, with four laterals on either side of the central 

 tooth. The central tooth has small detached side cusps and cut- 

 ing points, as in StropMa, and the laterals are quite similar — a 

 very unusual arrangement in the Heliciclce. The marginals are 

 low, wide, with one inner, oblique, wide bifid cutting point. 



The central, with its adjacent laterals and an inner marginal 

 tooth, are given in pi. XIV, fig. H. 



