140 REY. A. H. COOKE ON THE [Mar. 19, 
Puysa stnvara, Gld. (figs. 3, 3 a). 
Radula with about 83 rows (specimen probably imperfect) ; 
laterals rather more extensive than in the other species; outer cusp 
very small. Formula 25-12—1—-12-25. 
Hab. Viti Islands. 
Puysa TABULATA, Gray (figs. 4, 4 a). 
Radula with at least 220 rows; extreme marginals very much 
curved. Formula 32—8—1-8-32. 
Hab. New Zealand. 
Puysa aicr®, Reeve (figs. 5, 5 a). 
No special features. Formula 25-7—1-7-25. 
Hab. Australia. 
Puysa MULTIsTRIGATA, Tate (figs. 6, 6 a). 
Formula 30—8-1-8-30. 
Hab. Australia. 
Puysa paysopsis, Cooke (figs. 7, 7 a). 
Radula large, rows about 140; laterals numerous. Formula 
30—9-1-9-30. 
Hab. Australia. 
Puysa scaLaris, Dkr. (figs. 8, 8 a). 
Rows about 140, not so much curved as in the other species ; 
passage between laterals and marginals not distinctly marked. 
Formula about 25—7—1—7-25. 
Afab. Angola. 
Several interesting facts follow on this investigation. In the first 
place, the teeth of the radule bear a very striking resemblance to 
those of the African genus Isidora, Ehrenb. So far as Iam aware, the 
radula of Isidora has only once been figured, namely by Jickeli in his 
‘Fauna der Land- und Siisswasser-Mollusken Nord-Ost-Afrika’s’*. 
The resemblance amounts to identity; in Istdora the central tooth 
is squarish, bicuspid, the laterals tricuspid, the marginals serrate, 
just as in these Australian ‘ Phys,’ and the shells present no differ- 
ence whatever. Fischer, therefore, is quite right* in regarding the 
Australian and African genera as the same, and thus a most remark- 
able link is established between the molluscan fauna of Australia 
and Africa, a link in the chain of evidence already afforded by the 
existence of the carnivorous Land-Shells (Riytida) in both Conti- 
nents, and, amongst the marine Mollusca, by the occurrence of 
identical species of such littoral shells as Purpura and possibly of 
Littorina. 
In the next place, the relation of the group is much closer to 
Planorbis than to Limnea. A comparison of the central tooth and 
first lateral of Plan. corneus and of Limn. stagnalis (see figs. 9, 10, 
1 Nova Acta Ac. Nat. Cur. xxxvii. 1875, Taf. iii. figs. 2-4, 
2 Manuel de Conchyl. p. 509. 
