308 METACHATINA. 



first whorl; the axis is imperf orate and abruptly truncate at 

 base (pi. 23, fig. 46, specimen 10 mm. long). Type M. kraussi. 



Distribution, South Africa, Natal to Delagoa Bay. 



The soft anatomy is unknown. The longer spire, with bul- 

 bous nucleus, the diverse sculpture and flame marking of this 

 Natal species, all indicate that it is not to be included in the 

 same group with B. nilotica Pfr., but is a parallel evolution- 

 product from a different group of Acliatina. That it has 

 descended from a true Acliatina stock is demonstrated by 

 the young stages. The new-born young (pi. 23, fig. 46) hav- 

 ing the imperforate, curved, abruptly truncate axis of typical 

 Acliatina, but with advancing growth these features are 

 rapidly lost, and a Bulimoid aspect becomes apparent. If 

 Burtoa resembles the South American group of Stroplioclieilus 

 ovatus, Metacliatina is no less like 8. oblongus. 



The view advanced above of the affinities of this group is 

 not new. Prof, von Martens has already put on record his 

 opinion that kraussi and the nilotica group are parallel 

 groups, independently evolved by weakening of the Acliatina 

 characters in different stocks of that genus. His suggestion 

 that the name Burtoa might be restricted to the kraussi group 

 is not practicable, because the type of Burtoa was stated to 

 be nilotica. 



1. M. KRAUSSI (Pfeiffer). PL 23, figs. 46, 48. 



Shell openly rimate, ovate-acuminate, rather solid and 

 strong. Dull fleshy- white or soiled whitish, irregularly marked 

 with dull brown streaks on the spire, but wanting on the 

 apical and last whorls. Surface densely, finely and distinctly 

 granulose throughout, or the granulation may be obsolete on 

 the lower half of the last whorl. Spire straightly or a little 

 concavely conic, of about 8 whorls, the apex obtuse, rounded. 

 Last whorl somewhat tapering above, globose below. Aper- 

 ture ovate, less than half the total length of the shell, slightly 

 oblique, pure white inside, the columella, parietal wall and 

 a wide band within the lip of a deep blackish-chestnut color. 

 Outer lip obtuse, a trifle expanded; columella short, concave, 

 bounded by a slight channel at the base. 



