62 COLLECTIONS FROM MELANESIA. 



species, not mentioned by the above authors : — R. fimbriata, 

 R. flavesceng, R. grisea, and R. plicatula. Another species wbich 

 has also escaped attention is the Trochus melanostoma of Iteeve 

 ( Proc. Zool. Soc. 1842, p. 185; Conch. Syst. vol. ii. pi. 218. fig. 16). 

 Tin's is the same as Risella fimbriata of Philippi, which I think 

 should be regarded as a large form of R. melanostoma, Gmelin ; and 

 with this species I would also unite R.fiavescens and R. plicatula of 

 Philippi. I Junker has also described a species from Sydney under 

 the name of R. crassa, which appears to be remarkable on account 

 of a thickened channelled lip (Mai. Plat. 1861, vol. viii. p. 42). 



R. hielmannseggi, Zelebor, is the R. h/tra, Quoy, of which R. 

 imbricata may be a variety. The two following species resemble 

 Risella in form, but have the concentric multispiral operculum 

 of Trochus, from which they are distinguished by their non-pearly 

 apertures — Trochus tantillus, Gould, and Risella isseli, Semper. 

 The Tectarius luteus of Gould, Risella infracostata, Issel, R. par- 

 vula, Dunker ('? = tantillus), and Trochus conoidalis of Pease will 

 probably have similar opercula ; these four species differ from 

 Risella not only in the operculum, but in being narrowly per- 

 forated. The statement with regard to Risella a u rata being the 

 male of R. nana (although both are hermaphrodite) made by 

 Mr. Tenison- Woods (Proc. Linn. Soc. N". S. Wales, vol. i. p. 244), 

 and that " all breed freely with one another," seems to me to re- 

 quire some further corroboration. He himself hesitates to assert 

 positively that either of these two forms are incapable of repro- 

 ducing their own kind, " for there are many places on the coast 

 where no species can be found except the variety now known as 

 R. aurata." This, in my judgment, proves that that species at all 

 events is self-propagating ; yet Mr. Tenison-Woods says that 

 specimens of this species kept in glass jars for a few weeks did not 

 become fertile. Experiments rmtde for so short a time are far from 

 conclusive, especially when made under such artificial conditions. 



64. Rissoina clathrata. 



A. Adams, Proc. Zool. Soc. 1851, p. :?<>.*>; Schwartz von Mohrenstern f 

 Denkschrift. Ahad. Wissenschqft. Wten, 1861, vol. xix. pt. 2, p. 154, 

 pi. vi. tig. 49 ; Smith, Jburn. Linn. Soc. vol. xii. p. 553. 



Ifab. Prince of Wales Channel, 7 fms. (Coppinyer); Philippine 

 Islands (Cumin;/) ; var. minor, from the Caroline Islands (J. 

 Brazier). 



The specimen obtained by Dr. Coppinger is of a yellow-wax 

 colour, faintly tinged with rose towards the apex and at the aper- 

 ture. It has the upper whorls broken off. the remaining four and 

 a half measuring 10 millim. in length. The figures in Kiister's 

 ' Conchylien-C&binet,' pi. iv. tigs. 12, 13, do nol give the faintest 

 idea of this species, and probably represent another. 



