OF CONCHOLOGY. 187 



most truly remarked that tlie affinity of the Amphiperasidge to 

 the Cyprjeidae has been much exaggerated. To that learned 

 naturalist we also owe the definite approximation on substantial 

 grounds of the Amphiperasidos and PedicuJareacea* and the 

 combination of those two families in a technical but at the same 

 time natural group, f distinguished by the form of the lateral 

 teeth of the radula and their comb-like armature, and, it may 

 now be added, by the simple rolling of the shell on itself. Such 

 characters isolate them from the rest of the great group of Ta- 

 nioglossa. of which they are members, and, if any special name 

 is desired, the designation DiGiTOGLOSSA, (;ilthough a hybrid), 

 imagined by Gray for the Amphiperasidge, but soon afterwards 

 abandoned, may be taken up and extended to embrace the large 

 group. 



As the young shells of Amphiperasidse are rare in cabinets, it 

 may not be superfluous to add that their character can be ascer- 

 tained by a longitudinal section of the adult. 



* Messrs. Adams admit three families— Cypragidas, Amphiperasidae and 

 Pediculariidse (i, p. 263 — 274) and Dr Chenu has united all in one family 

 — CypraBidae (i, p. 264 — 274, 1859) — but no reasons fcr such juxtaposition 

 are given, or are apparent from the diagnoses or remarks. 



fTroschel, Gebiss der Schnecken, ii, p. 12, 1866. 



