MOLLUSCA. (11 



The L. Icevis of Reeve is also L. mauritiana, and quite distinct from 

 the L. Icevis of Philippi (/. c. vol. iii. p. 10, pi. 6. tig. 6), which is 

 also from the Mauritius. /,. undulata of Gray is also considered a 

 variety of L. mauritiana by Mr. Tenison-Woods (/. <•. p. 72) ; hut 

 here I think ho overstrains the power of variation. Besides the 

 difference in form and colour, the violet columella and sculpture 

 readily distinguish that shell. In adopting the Lamarckian name 

 L. cwrulescens, even supposing the Mediterranean and Australian 

 shells were the same species, 1 think Mr. Tenison-Woods is wrong, 

 considering what is said upon this point by Philippi (op. cit. vol. ii. 

 p. 166), llanley ('Ipsa Linnau Conchylia,' p. 32t>), Jeffreys, and 

 others. 



63. Risella lutea. 



Trochus luteus, Quoy 8r Gaimard, Voy. ' Astrolabe,' vol. iii. p 271, 

 pi. 62. tigs.. 8-11 ; Kiener, Coq. Viv. pi. 38. fig. 2. 



Trochus cicatricosus, Jonas, PhilippVs . Ibbild. pi. 2. fi?. 2. 



Bembicium luteum, Philippi, Zeitsch. Mai. 184(">, p. 132. 



Risella lutea, Philippi, Kit, iter's Con.- Cab. p. 4, pi. 1. figs. ], 2. 



Risella kielnmnnse^i, Zvlc ! "ir, Ve rhandl. zool.-botan. Gesellsch. Wien, 

 18G6, vol. xvi. p. 913; Voy. ' Nbvara,' pi. xi. tigs. 11 a-d. 



Bab. Port Jackson, Port Denison, Port Curtis, and Port Molle 

 (Coppinger). 



This genus has been suppressed by Mr. Tenison-Woods (Proc. 

 Linn. Soc. N. S. Wales, 1879, vol. iii. p. 61); but, in my judgment, 

 it may be retained with advantage as distinct from Littorina. The 

 Trochoid form and flattened base of the species is not approached in 

 that genus, and the character of the columella is very different. 



According to Mr. Tenison-Woods there is but one species otRisella 

 in Australia (R. melanostoma of Graelin), under which name he 

 includes fifteen varieties or species, which have been named and 

 described by Lamarck, Quoy, Gray, Philippi, and others. 



Although the separation of many species or constant local forms 

 seems impossible, we must not therefore ignore their existence. 

 Risella bruni is a South-Australian shell, and does not attain any 

 thing like the size of several of the other species, e. g. R. nana, 

 R. melanostoma, and R. imbricata. Although it might be possible 

 to get together an immense series of specimens which would unite 

 step by step the two most extreme forms, nevertheless the R. bruni 

 would still remain the small species from South Australia, and the 

 other, the R. imbricata from Sydney, Port Stephens, &c, would also 

 be recognizable as such. 



I am far from admitting the validity of all the described species ; 

 but there are some, I think, which may be retained, at all events, 

 with convenience. It is not my intention now to discuss this subject 

 further, but, in conclusion, will call attention to Philippi's mono- 

 graph of the genus, which has been altogether overlooked by Crosse 

 ( Journ. de Conch. 1864) and by Tenison-Woods ; it was published 

 in 1853 in Kiister's ' Conchylien-Cabinet,' and contains the following 



