360 On a new Species of Opisthostoma. 



At p. 382 we fiud Pyripora, d'Orbigny, 1847, type 

 P. catenar'ia, Jameson. I have not seen cVOrbiguy^s 

 paper of 184^7, but in his ' Paleoiit. Fran9aise/ Terrains 

 Cretace, 1850-1852, p. 538, under the genus Pyripora 

 there is no reference to the species in question, and the 

 fossil species referred by Cauu to this genus would 

 scarcely seem to be congeneric with M. catenularia. 



Vol. xii. p. 100, lines 6 & 13. — For Membraniporella, Hincks, 

 read MembraniporeUa, Smitt. 



XLIV. — Description of a neiv Species o/ Opisthostoma //-(^jh 

 JVorth Borneo. By Edgar A. Smith, 1.8.0. 



Altogether twenty-three species of this genus from the 

 northern parts of Borneo have been described, and probably 

 many other forms still remain to bo discovered. 



Opisthostoma fratcrnum, sp. n. 



Testa dextrorsa, pyramidalis, angiiste umbilicata, rufescens ; an- 

 I'ractus G|, regularitcr lente accrescentes, perconvexi, lamellis 

 paucis, teimibus, obliquis, in medio anfractuum in spinas pro- 

 diictis, instructi, ultimus pone constrictus, dcin descei ulcus et 

 subito ascendens atque retroversus, autice solutus, infra spiiiis 

 excavatis cri&tatus ; apertura siibcircularis ; peristoma obliijuura, 

 duplex, album, margine interne expanse, tubajformi, externo 

 tenuissimo, aliquanto dilatato. 



Diam. max. 2-75 mm. ; alt. 2-25. 



The identification of many of these minute objects is almost 

 impossible or, at all events, very uncertain, from description 

 or figures such as have as yet a])peared. It is only by actual 

 comparison of specimens that the differences become appreci- 

 able. The present species bears a closer resemblance to 

 0. conciiinum, Fulton, than to any other. It differs from it, 

 however, in being a trifle smaller, having more convex and 

 higher whorls, fewer laniel'oe, and the outer peristome is less 

 interrupted on the right side. The delicate oblique lamellai 

 are about fourteen in number upon the penultimate whorl 

 and are produced at the middle into short hollow spines 

 directed obliquely upwards. This row of spines is continued 

 under the body-whorl, forming a crest, between the constric- 

 tion and the peristome, of about six or seven spines. The 

 distance of the solution of the anterior portion of the body- 

 whorl is a trifle variable. Even under the microscoj)e no 

 spiral sculpture is traceable, but some feeble lines of growth 

 may be observed. 



