I 



EASTERN PROVINCE SOUTHERN REGION SPECIES. *437 



Pineria, Partula, and sonic species of BuUmnlns also have an upper 

 median triangular compartment to their jaw; but in their case the jaw 

 is in one single j^iece, with distant, delicate ribs, running obliquely to 

 the central line, some of the upper ones meeting before reaching the 

 lower margin of the jaw, thus leaving a triangular space, not a separate 

 piece. 



I have myself figured the jaw of 0. melanochilus, Val., under the 

 name of 0. zehra (L. and Fr.-W. Shells N. A., I, 215, Fig. 367), of 

 galUna-statana (Ann. N. Y. Lye. Nat. Hist., XI, Plate IV, Fig. E). The 

 last-named has also been figured by Troschel (Arch, fur Nat., 1849, 

 Plate IV, Fig. 3) ; the jaw of 0. iostomus is figured by Crosse and 

 Fischer (Moll. Mex. et. Guat., Plate XIX, Fig. 8), and 0. longus by the 

 same authors {I. c, Plate XIX, Fig. 1). I have also examined the jaw 

 of 0. obductus, Shuttl. (Ann. Lye. X. H. of X. Y., XI, 37). All these 

 species have the same composite type of jaw. 



The lingual dentition of OrtlialicuH undatus is so nearly similar to 

 that of Hguus fiisdatus that I merely compare it with the description 

 given above of that species. The membrane is broad (see Terr. Moll., 

 V, Plate XVI, Fig. xAI). In 0. undatus the central tooth (Plate X, Fig. 

 H) is broader in proportion to its length; the base of attachment is 

 less expanded at the upper margin, and very much less so at its lower 

 margin, and the sides are not incurved ; tbe cusp is stouter, longer, 

 reaching the kwer edge of the base of attachment, and it has subobso- 

 lete but distinctly marked side cusps ; tiie cutting edge is much more 

 expanded, overlapping the next row of teeth. The first marginals 

 diifer from those of L. fasciatus in having a less developed cutting- 

 edge, the outer marginals have the side spurs to their cusps much 

 more developed, and even the cutting edge is trilobed. The extreme 

 marginals are not so small. There are about 53-1-53 teeth on one part 

 of one membrane; a wide part of another membrane had lOG-1-106. 



All the species of Orthalicus enumerated above whose dentition is 

 known have the same type of teeth as 0. undatus excepting 0. gallina- 

 sultana. This last (see Ann. Lye. X. H. of X. Y., XI, 38, Plate IV, 

 Fig. A) is peculiar iu having a long, stout cutting point, with subobso- 

 lete side points to its central tooth, and three lateral teeth of same form 

 but asymmetrical. The dentition of 0. obductus is very similar. Thus 

 in both Liguus and Ortlialicus we find the usual type of dentition is not 

 constant excepting as to the marginal teeth 



I have also examined the form figured in Terr. Moll., IV, Plate 



