3A 
ON RHIOSTOMA DALYI, n.svp.. AND SHSARA MEGALODON, n.sp., 
OBTAINED BY THE LATE MR. W. M. DALY IN SIAM. 
By W. T. Branrorp, LL.D., F.R.S., ete. 
Read 10th January, 1902. 
Tue two shells here described were sent to me with others by the 
late Mr. W. M. Daly shortly before he died. I hoped to have given 
a list of his Siamese collections, but have not yet been able to complete 
the identification of all the forms. 
Pitsunaloke, whence both the species come, is about 220 miles north 
of Bankok. 
1. Rurostoma Datyr, n.sp. Fig. I. 
Testa late umbilicata, convexo-depressa, solida, striatula, sordide 
albida, superne flammulis irregularibus castaneis variegata, intra 
peripheriam fascia angusta circumdata ; spira depresso-conoidea, apice 
prominulo, sutura canaliculata; anfr. 5 potent ultimus cylindricus, 
antice longe solutus et descendens, superne a sutura usque ad tubulum 
marginalem obtuse carinatus ; apertura obliqua, diagonalis, circularis ; 
peristoma duplex, superne ad sinistram incisum et tubulo elongato, 
retro valde curvato, anfr. penultimum attingente, ad ambas extremitates 
aperto, munitum. Operculum testaceum, multispiratum, breviter 
cylindricum, extus planatum, intus profunde excavatum. Diam. 
maj. 26, min. vix 20mm.; alt. 10°5 mm.; apert. diam. intus 8 mm. 
os D 
WW \\ 
Fic. I.—Rhiostoma Dalyi, n.sp. 
Hab.—Juxta Pitsunaloke, in sylvis humidis et densis. 
This is nearly allied to R. Hainesi, Pfr., and R. simplicilabre, Pfr. 
The first is larger than R. Daly, and the diameter of its whorls 
is proportionately greater; its mouth, too, is more expanded, but 
the highly curved tube, running back from the peristome to the 
penultimate whorl, is similar, whilst that of . simplieilabre is 
quite differently directed, and the peristome in the latter is simple. 
Rk. Haughtoni, Bs., from Moulmein, is a much smaller form than 
Rk. Dalyi, and has the free portion of the last whorl shorter, and 
a very small tube arising from the peristome. The other two species 
