May. I Mathews AtiD Irbvalk, " Perry's Arcana." ii 



Plate XII. is of Pomacea maculata, which " is conceived to 

 be a naiive of the South Seas." This is the first use of the 

 generic name Pomacea, which is a synonym of Ampiillaria, 

 Lamarck. The s])ecies we cannot recognize, while the habitat, 

 when it was re-figured in the " Conchology," pi. .xx.wiii., 

 fig- 3> was altered to West Indies. 



Plate XV. contains figures of four fossil shells, named Conns 

 angiilatus, Aciilea angulaia, Cerithium Icevis. and Cassis 

 verrucosa, of which is written: — "The above shells are of the 

 kind found in different i)arts of France, in beds of gravel or 

 clay." 



Plate XVT. purports to be a figure of Conns gloria-»taris, 

 and a shell in the British Museum is mentioned. When the same 

 figure was reproduced in the " Conchology," pi. xxv., fig. i, 

 it was definitely said to be " delineated from a fine specimen 

 in the British Museum." The figure seems, however, to have 

 been drawn from a nice specimen of Conns textilis ; moreover, 

 no record is kept of a British Museum specimen of Conns 

 gloria-maris at that early date. Perry notes : — " The Conns 

 has a considerable analogy to the genus Volntella, lately- 

 established." 



Plate XIX. is a good representation of " Bnlinins zebra, a 

 native of the Soutfi Seas and of the islands of New Zealand," 

 which shows a quaint mixing of localities, the shell being the 

 well-known Achatina zebra. Gmelin, of Africa. 



Plate XXIII. introduces the genus Triplex, the species name 

 chosen being foliatns. This is a splendid figure of the shell 

 many years later named M. palmarosce-, Lamarck (Anim. s. 

 Vert., vol. ix., p. 572). When, later. Perry reproduced the 

 same figure in the " Conchology " (pi. vi., fig. 3). he altered 

 the specific name to T. rosaria, and the reproduction is not 

 such a nice picture as the " Arcana " one. Thus by monotypy 

 the type of Triplex is T. foliatns. Perry, and the sjiecific name 

 supersedes M. palmarosce. Lam. 



Perry remarks : — " The Triplex genus of shells are re- 

 markable for their triangular form, which is occasioned l')y three 

 tfiick divisions placed lengthwise on the outside of the shell, 

 and which form its chief ornament Other shells, which in 

 many respects have a resemblance to it, are distinguished in 

 a similar wa}' : the Monoplcx has one fold on its body : the 

 Biplex two folds : the Hexaplex six folds, and so on with the 

 following sjiecies. until we arrive at the greatest mimber. the 

 Polyplex, in which the folds are very numerous, but the 

 number not defined." 



Plate XXVIII. contains figures of (\\<d shells, the centre one 

 being Scalaria disjnncia. the Tnrbo scalaris, Linne. Of the 

 other four is written :— " The four small shells which accom- 



