1 60 Quarterly Journal of Conchology. 



Journal de Gonchyliologie, January 1876. 



Crosse, H. — Monographic du Genre Rhodea (Monograph of 

 the Genus Rhodea), pp. 5 — 24. 



This section was founded by Messrs. H. &: A. Adams in 1858 

 for Achatina California, Pfr., and considered as a subgenus of 

 Columna. 



In 1873, M. Mousson described a second species, R. gigantea, 

 from New Granada, and raised the section into a genus, a view now 

 generally adopted. 



With regard to the place of the genus in the classification of the 

 Helicidee, various opinions have existed. 



As we have seen, Messrs. Adams considered that the Rhodea 

 were intimately allied to the Columna; but both by their forms 

 and by their being ovoviviparous, whilst the Columnce are viviparous 

 they are quite different, and this is confirmed by the geographical 

 distribution of the two genera. Columna is a West African genus, 

 is in fact merely a somewhat abnormally developed and elongated 

 Achatina, whilst Rhodea is exclusively South American. 



Dr. Kobelt places Rhodea next to Megaspira, also an exclusively 

 South American genus and extremely elongated. 



M. Crosse thinks that the genus we are considering should be 

 placed next to Stenogyra. The first whorls are almost exactly the 

 same as those of S. octona, L., and M. Mousson, who has examined 

 almost embryonic specimens of R. gigantea, compares them with 

 Lcptinariic minus the parietal lamella, and Leptinaria and Stenogyra 

 belong to the same family. 



[As M. Crosse remarks, the study of the animal can alone definit- 

 ively fix the position of the genus, but whilst admitting with the au- 

 thor that there are many points of resemblance between Rhodea and 

 Stenogyra we cannot help also seeing an analogy with Megaspira. 

 In our collection we have arranged the genera as follows, Steno- 

 gyra, Spiraxis (s. stride), Rhodea, Megaspira, Balia. Clausilia. 

 This seems to us to reconcile both views-r- Rhodea being in fact 



