344 Mr. T. G. Ponton on some Species of Oliva 
XLIV.—Remarks on some Species of Oliva recently described 
by Mr. Frederick P. Marrat. By 'T. Granam Ponton, 
F.Z.8. 
In the ‘ Annals,’ ser. 3. vol. xx. p. 213, Mr. Marrat published 
descriptions of twelve new species of Oliva, With your per- 
mission | 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 Mir. 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 O. re- 
ticularis.. The interior of the aperture is. pale bluish—thus 
making a decided approach to Mr. Marrat’s shell. In fact T 
cannot help thinking that O. violacea is nearer the typical 
form of O. reticularis than some Californian examples of the 
species in our Museum, which are of a deep brown, marbled 
with a darker colour; the columella in these examples is 
of a full, rich brown tint. Similar specimens are figured in 
Reeve’s monograph. 
- Oliva gamarcensis, Marrat.—This shell, Mr. Marrat remarks, 
is intermediate between O. splendidula and O. reticularis. 
This observation goes far to prove that the opinion entertained 
by many conchologists respecting the identity of the two i - 
cies mentioned is a correct one. I cannot distinguish Mr. 
Marrat’s shell from varieties of O. reticularis with a depressed 
spire—a feature which is not uncommon even in very typical 
forms of the species. 
Oliva polita, 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. Marrat’s description. | 
Oliva piperata, Marrat.—Mr. Marrat remarks that this shell 
is allied to O. conotdalis, Lam. The O, conotdalis of Lamarck 
is simply a variety of O. jaspidea. Is not Mr. Marrat’s shell 
the same ? 
Oliva faba, Marrat.—This shell, Mr. Marrat observes, is 
