60 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



attitude, and will probably be confirmed when the anatomy comes 

 to be examined. The genus is distributed over China, Tonkin, 

 Cambodia, and Formosa, with an outlying species in the Loo-Choo 

 Islands. It is characterized by the absence of internal barriers on the 

 parietal wall. In the subgenus Moellendoeffia, s.s., comprising 

 ten species, the outer edge of the parietal callus is solute, erect, and 

 sinuous, bearing a short, raised tooth at the sinus ; generally there 

 are besides two furrows or sulci on the outer and basal wall, with 

 corresponding lamellae internally. In the subgenus Moellen- 

 DORFFiELLA, Pilsbry, with only one species known — M. erdmanni, 

 S. & B., from China, a flattened shell with sunken spire — the parietal 

 callus is without the raised, sinuous edge, and the margins of the 

 peristome are approximating. The subgenus Trihelix, Ancey, on 

 the other hand, has the edge of the parietal callus slightly raised, 

 but it is not sinuous and devoid of the raised tooth characterizing 

 the first subgenus. M. horrida, Pfr., a Tonkin species, has two short 

 sulci at the upper part of the last whorl — one behind the peristome, 

 the other a short distance back, their upper ends convergent — and 

 a similar one on the base, also behind the peristome, these three 

 sulci having corresponding short lamellae inside and forming 

 a triangle. M. hiraseana, Pilsbry, from Formosa, has a long, curved 

 scrobiculation at the upper part of the last whorl, a short distance 

 behind the peristome, and a shorter, oblique one on the base, nearer 

 the peristome, both with corresponding lamellae inside. M. 

 eucharistus, Pilsbry, a Loo-Choo species, is simply furnished with a 

 very short sulcus on the base of the last whorl, close to the peristome, 

 the corresponding short lamella inside being only slightly raised. 



Genus Stegodera, Martins, 



and its subgenus Traumatophora, Ancey, were for many years 

 classed as subgenera under Plectopylis, until in 1905 Dr. Pilsbry 

 suggested their relationship to Moellendorffia. Each contains only 

 one species from China. The former is represented by a sinistral 

 species — S. angusticollis, Mts. — which is devoid of internal barriers, 

 but the last whorl is strongly constricted a short distance from the 

 aperture, leaving only a narrow slit for the animal to emerge. The 

 latter is represented by a dextral form — S. triscalpta, Mts. — which 

 is also constricted a short distance from the aperture, but only slightly 

 so. It is, on the other hand, furnished at the same place with three 

 strongly developed sulci, the two uppermost long, curved, ascending 

 at first, then slightly descending and terminating close to the 

 peristome ; the one at the base shorter, oblique ; all three have 

 corresponding elevated lamellae inside the mouth, closely approaching 

 the inner walk 



Genus Corilla, Adams. 



In the present genus and the next— Plectopylis — the internal 

 armatures reach an extraordinary development. A careful 



