144 JOURNAL OF CONCHOLOGY, VOL. I4, NO. 5, JANUARY, I9I4. 



I understand that the indications of the shell are in general agreement 

 with those of the radula, though perhaps less conspicuous. 



Taking, then, the genus Ancylus — in a wide sense — to include 

 Ferrissia, Lczvapex, Latix, and even Velletia (but not Latia) and 

 classifying by the radula alone, it falls into four well-marked sections, 

 with very different radulse and significant geographical distribution. 

 The first or northern section is represented by Ancylns fliiviatilis 

 Miill. Of this I have examined eight species : — 



A. captiloides Jan. A. abyssinicus Jick. 



A. fluviatilis IMiill. A. adnncus Gld. 



A. orbicularis Clessin. A. recurvus Parr. 



A. simplex Easter. A. striains Quoy. 



It is found all over Europe and beyond, as far certainly as Madeira, 

 Oran, Damascus, and Abyssinia, and probably over Northern Asia ; 

 but I have no evidence that it reaches India. In this the radula is 

 long, and the lateral teeth are simple hooks in nearly straight rows, 

 while the marginals have two cusps, the larger inside, but so short 

 that they seem set on plates. The jaw is delicate, and segmented in 

 plates, like that o'i Piindum pygmceuni. 



The second section is represented in my cabinet by Aficylus 

 laciistris L. only. Its distribution is similar to the former, but more 

 limited. It certainly reaches from Norway to Transylvania, though 

 apparently not to Sicily or Syria, and certainly not to Africa. At first 

 sight the radula is quite different. The arched rows of laterals with 

 expanded bases and hooks with minute denticles remind us of the 

 Trochidce ; while the plate-like marginals recall the Docoglossa. Yet 

 they all seem modifications of the broad hooks of the first section, 

 and I see no reason to suspect any more distant afirnities. 



A third — what I have called the Southern section — must be ex- 

 tended to include the similar radulse of Gundlackia, Aviphigyra, and 

 Neoplanorbis. I have examined thirty-two of these (N). They repre- 



(N). Type (A). 



Africa. — 



A. burmipi Walker. A. mooiensis Walker. 



A. equeefefisis Walker. A. ? compressus Jick. 



A. transvaalensis Craven. A. taiigatiyiceusis Sm. 



A. differ Krss. 



India.-— ■ ■ ; 



A. verruca Bens. A. sp. (Calcutta). 



Tasmania. — 



Gundl. petterdi Johnst. - ., 



