456 Mr. W. T. Blanford on the Classification of 



by its sculpture, which is distinct in general from that of any- 

 other of the Cyclostomacea, except Diplommatina, and in the 

 absence of any tendency to coloured zigzag markings — a cha- 

 racter which may not appear of much value at first, but which 

 is nevertheless singularly constant throughout the genera Cyclo- 

 phorus, Pterocyclos, Opisthoporus, Cyclotiis, &c. — in fact, nearly 

 all the Cyclophorince, The animal is similar to that of Pupina, 

 having short, black tentacles, and differs in no essential point 

 from Cyclophorus. 



The large addition to the number of species renders it possible 

 to define more exactly the generic characters ; and the following 

 may be suggested : — 



Testa perforata v. umbilicata, conica, turbinata, globosa vel de- 

 pressa, unicolor, albido- v. succineo-cornea, rarius rubella. Anfractus 

 convexi, ultimus ad latus tumidus (spatio inflate sculptura confertiore 

 plerumque ornate), deinde prope aperturam constrictus, tubule su- 

 turali externe, pone stricturam eriente, antice in anfractu aperte, 

 cum spatio inflate longitudine concordante, postice clause munitus. 

 Peristoma circulare, plerumque incrassatum vel reflexum. Operculum 

 corneum (rare subtestaceum ?), multispirum, nucleo centrali interne 

 preminente seepe munitum. 



In the ' Ann. & Mag. Nat. Hist.' for March 1859, Mr. Benson 

 suggested the division of the genus into a typical section and 

 two subgenera, which he named Charax and Dioryx, distinguish- 

 ing the three sections by the characters of the constriction, the 

 typical group embracing such species as have " the last whorl 

 constricted somewhat remotely behind the aperture, tumid on 

 both sides of the constriction .'' In the section Charax, the 

 constriction is '' broad, contiguous to the aperture, and divided 

 more or less remotely from it, across the whorl, by a ridge, 

 which is hollow internally." In Dioryx the constriction is 

 "narrow and immediately behind the aperture." 



This distinction appeared at the time to be good, with the 

 exception that one of the species referred to Dioryx [A. crenu- 

 latus, Bens.) was more closely allied in most of its characters to 

 a form of Charax than to the members of its own section. But 

 there was evidently, after the removal of this species, a much 

 closer alliance between Charax and the typical group than be- 

 tween either of those types and Dioryx. To this Mr. Benson 

 referred in his paper, and also to the fact that the Western 

 Himalayan species, A. strangulatus, Hutt., showed a tendency to 

 a passage from Charax to the typical section. Since the publi- 

 cation of Mr. Benson's observations, some other species have 

 been discovered, especially A. Theobaldi, W. Blanf., and A.poly- 

 gonoma, W. Blanf., which are also intermediate in the characters 

 of the constriction ; and it may be doubted whether the form of 



