WATSON: ON KBAPFIELLA MIBABILIS. 137 



proportion to their length. The cusp of the central tooth is not 

 quite so small ; the mesocones of the other teeth are shorter, and 

 two ectocones are present on some of the marginal teeth. The 

 number of teeth in one of the posterior rows is 9 + 7 + 1+7 + 9. 

 Further forwards the number of teeth diminishes, until near the 

 front of the radula a transverse row only contains 3 + 3 + 1 + 3 + 

 3. The form of the teeth also gradually changes (Fig. G). They 

 become still broader and shorter ; the central tooth becomes 

 relatively larger, with a prominent narrow median cusp and traces 

 of a minute lateral cusp on each side of it ; the mesocones of the 

 other teeth become rounded, and their inner flanges become partly 

 separated from them, so as to form distinct endocones. Thus, with 

 the exception of the extreme outer marginals, which have no cusps, 

 all the teeth at the front end of the embryonic radula are more or 

 less tricuspid. 



The other internal organs were unfortunately so shrivelled and 

 decayed that it is not possible to describe them. All that could 

 be made out of the reproductive organs is shown in Fig. D. 



Affinities. — Although evidently belonging to the Achatinidae, 

 Krapfiella mirahilis differs considerably from most members of that 

 family both in its radula and in its foot. There is, however, one 

 genus of the Achatinidae, namely Pseudoglessula, in which the radula 

 and the foot bear a remarkably close resemblance to those of the 

 present form. Moreover, the shell of Krapfiella mirahilis is not very 

 unlike the type found in the species of Pseudoglessula belonging to 

 the subgenus Kempioconcha, in which the columella is not truncate 

 or folded, and a narrow umbilicus is usually present. The chief 

 differences between Krapfiella and Pseudoglessula are to be found 

 in the broad, rounded apex of the former genus, and especially in 

 the apical structure ; for in both Kempioconcha and Pseudoglessula, 

 S.S., the protoconch bears strong vertical ribs, very unlike the regular 

 spiral striae of the present species. Nevertheless, there can be 

 little doubt that Krapfiella is fairly closely related to Pseudo- 

 glessula. 



These two genera together form a very aberrant group of the 

 Stenogyrinae, differing from the other known forms in their deep 

 peripodial grooves and caudal mucous pore — in which they resemble 

 the Ferussaciinae and the families of the Aulacopoda — and also in 

 their peculiar type of radula. Pilsbry has pointed out, however, 

 that the radula in Pseudoglessula somewhat resembles that of a 

 rapacious snail,^ and the marginal teeth of these genera certainly 

 bear a suggestive similarity not only to those of Arion, but also to 

 the teeth of the Oleacinid genus Varicella. Probably, therefore, 

 the peculiarity of the radula in Krapfiella and Pseudoglessula may 



1 Bull. Amer. Miis. Nat. Hist., vol. xl, 1919, p. 148. 



