RIIIOSTOMA. 
39 
castaneis variegata ; spira parum elevata, vertice minuto, corneo; 
anfn 5 depresso-rotundati, ultimus infra peripheriam castaneo- 
unifasciatus , antice longe solutus et deflexus, a sutura ad 
tubulum carinatus, ante tubulura introrsum apertum, extus 
longe recurvatum leviter incisus ; apertura obliqua, circularis ; 
perist. subduplicatum, album , margine sinistro incrassatum, 
dextro expanse, plane paiente. — Opera cyathiforme, extus 
planum , anguste spir^tum , marginibus anfractuum elevatis, 
membranosls^ — Diam. maj. 35, min. 25, alt. 12 — 14 mill. 
Apert, diam. 11 — 12 mill. (Mus. Cuming et Coll. Nr. 45.) 
Rhiosioma Hainesi Pfr. in Proc. Zool. Soc. 1862. p. 115. t. 12. f. 8. 
Pterocyclos Haincsii Reeve Conch, ic. sp. 19. t. 4. 
Habitat Camboja (Mouhot). 
3. Rh. @iniplicilabre Pfr. 
T. late umbilicata, depressa, solidula, leviter et confertis- 
sime striatula, sub epidermide nitida lutescens, elegantissime 
et subtiliter castaneo-flammulata ; spira breviter conoidea, vertice 
minuto, obtusiusculo ; anfr. 5 depresso-rotundati, ultimus infra 
peripheriam castaneo-unifasciatus , antice sublon^e solutus et 
deflexus , a sutura Usque ad tubulum recurvatum carinatus ; 
apertura diagonalis, subcircularis, intus coerulescenti-margari- 
tacea; perist. simplex, tenue, »ante tubulum leviter incisum, 
undique vix expansiusculum. — Operc. praecedentis, angustius 
spiratum. — Diam. maj. 27^/2, min. 19^/2, alt. 10 mill. Apert, 
diam. 8^/3 mill. (Mus. Cuming.) 
Rhiosioma simplicilabre Pfr. in Proc. Zool. Soc. 1862. p. 115. t. 12. f. 7. 
Pterocyclos simplicilabris Reeve Conch, ic. sp. 20. t. 4. 
Habitat Camboja (Mouhot). 
4 . Rli. Haiigbtoni Beneoii. * 1 * 
„T. late umbilicata, convexo-depressa, solidiuscula, oblique 
scabre striatula, superne castanea, subtus albida, fascia angusta 
mediana saturation, utrinque angulato-marmorata, ornata; spira 
depresso-conoidea, apice prominulo, obtusiusculo; sutura im- 
pressa ; anfr, 5, convexiusculis, ultimo cylindrico, antice longe 
soluto, lateraliter descendente, superne carina obtusa a sutura 
usque ad tubulum marginalem decurrente munito; apertura 
libera, obliqua, diagonali, circulari, peristomate subduplici, 
extus incrassato , reflexiusculo , superne ad sinistram inciso. 
216. 
217. 
