Dr. J. E. Gray on the genus Assiminia. 427 



Mr. Clark would have quoted his authorities more correctly, if 

 he had stated, — first, that Dr. Philippi referred his third species 

 (t. 24. f. 4) to the genus with a mark of doubt ! — as he never 

 examined the animal. It is the figure of this species which Mr. 

 Clark thinks " may be intended to represent our Truncatella 

 Grayana." On this head it is only necessary to observe (and 

 showing, at the same time, the dependence to be placed in Mr. 

 Clark^s quotation of synonyma), that as Dr. Philippi found this 

 species very frequently in the sea at Palermo, it is to be sup- 

 posed that he had observed it in all its ages ; and he describes 

 "the shell as half a line high, and one-third of a line broad, 

 subturrited, blunt, the whorls rounded, the last not ventricose" — 

 which does not very exactly fit our Assiminia Gray ana, as the 

 latter lives in brackish water, often at such a distance from the 

 sea, that, after rains, the ditches are nearly fresh — measures 

 one-third or more of an inch in length, is of a conic shape, acute 

 at the top, and with scarcely raised whorls, the last somewhat 

 angular in front. I could as soon believe that the littoral Pur- 

 pura Lapillus and the pelagic Buccinum undatum were the same 

 species, as they do not differ in more important characters ; and 

 I feel assured that ^Ir. Clark proposes to unite in his work 

 many species from superficial examination and incorrect compa- 

 rison. 



Secondly, Mr. Clark might also have stated, that Professor 

 Forbes and Mr. Hanley have removed one of the species {T. 

 atomus), which Dr. Philippi had described as belonging to the 

 genus Skenea ; and that Air. Clark himself, in his ' Mollusca,' 

 p. 386, refers this species to the genus Truncatella with doubt ! 

 And while on this species t may observe, that I must beg to 

 doubt the accuracy of Mr. Clark^s observation, when he states 

 that this species, which has a circular mouth to the shell and a 

 cylindrical body to the animal, has an " operculum which is 

 precisely of the same grossly spiral character and sculpture as in 

 Truncatella Montagui and Truncatella littorea" — which have an 

 ovate mouth to the shell, and the body of the animal com- 

 pressed; such a combination of characters being directly at 

 variance with all my experience. I am assured that T. atomus, 

 on the contrary, has a circular multispiral operculum like Tro- 

 chus, which, according to Mr. Clark^s most extraordinary theory, 

 ought to remove it from Truncatella to quite a different order 

 in his sexual system of Mollusca. It is to be regretted that Mr. 

 Clark observed the operculum of this species so superficially, 

 when he professes to have been able to see a white pupil on the 

 eye of a dried specimen of the animal, which animal in its entu'e 

 state is scarcely a quarter of a line in diameter ! 



