344 Mr. T. G. Ponton on some Sjjecies of Oliva 



XLIV. — Remarhs on some Species of Oliva recently described 

 by Mr. Frederick P. Marrat. By T. Geaham Ponton, 

 F.Z.S. 



In the ' Annals,' ser. 3. vol. xx. p. 213, Mr. Marrat published 

 descriptions of twelve new species of Oliva, With your per- 

 mission I would beg to make a few remarks upon some of 

 them. 



The genus Oliva is one of the most interesting to the stu- 

 dent of variation. Colour, which has been so frequently 

 taken as a guide in the determination of specific differences in 

 shells, here almost completely fails. This has been well shown 

 in the fine monograph of the genus published by the late Mr. 

 L. Reeve ; and I cannot help thinking that Mr. Marrat has 

 somewhat lost sight of the fact. 



For example, the Oliva violacea described by him is almost 

 identical with some specimens of Oliva reticularis, from Ma- 

 zatlan, in the Museum of the Bristol Philosophical Institution. 

 These shells have the pale zigzag lines and semilunar dots 

 described by Mr. Marrat. The base of the columella is stained 

 with violet, which, by the way, is a marked character of 0. re- 

 ticularis. The interior of the aperture is pale bluish — thus 

 making a decided approach to Mr. Marrat's shell. In fact I 

 cannot help thinking that 0. violacea is nearer the typical 

 form of 0. reticularis than some Californian examples of the 

 species in our Museum, which are of a deep brown, marbled 

 with a darker colom-; the columella in these examples is 

 of a full, rich brown tint. Similar specimens are figured in 

 Reeve's monograph. 



Olivajamaicensisj Marrat. — This shell, Mr. Marrat remarks, 

 is intermediate between 0. splendidula and 0. reticularis. 

 This observation goes far to prove that the opinion entertained 

 by many conchologists respecting the identity of the two spe- 

 cies mentioned is a correct one. I cannot distinguish Mr. 

 Marrat's shell from varieties of 0. reticularis with a depressed 

 spire — a feature which is not uncommon even in very typical 

 forms of the species. 



Oliva 2>olita, Marrat. — I cannot help thinking this shell is 

 merely a variety of O.jaspidea, which varies much both in 

 form and colour : certainly varieties of that species in our 

 Museum answer well to Mr. Man-at's description. 



Oliva piperata, MarrM. — Mr. Marrat remarks that this shell 

 is allied to 0. conoidalis, Lam. The 0. conoidalis of Lamarck 

 is simply a variety of O.jaspidea. Is not Mr. Man-at's shell 

 the same ? 



Oliva faba, Man-at. — This shell, Mr. Marrat observes, is 



