No. 556] 



NOTES AND LITERATURE 



255 



port his contention. Why should we regard the first finger as 

 having been lost? It would be interesting to have Abel's further 

 views on this matter. The oldest amphibian has but four digits 

 in the hand and they doubtless never had more, but we don't 

 know. His discussion of the origin of tfa thumb is open to 

 question as has been suggested by Doctor Matthew in a pre- 

 vious review of this work. The work as a whole is well printed; 

 the illustrations are clear and show care in selection. The work 

 is, I am sure, a welcome addition to our libraries. 



Whatever we may think of the "Arachnid Theory" for the 

 origin of the vertebrates, as outlined in Patten's "Evolution of 

 the Vertebrates and their Kin," we must all acknowledge our 

 debt to Professor Patten for the information on the oldest known 

 vertebrates as outlined in Chapters XX and XXI of that work. 

 Those of us especially who are engaged in the attempt of teach- 

 ing something of the nature of the oldest known vertebrates must 

 feel grateful to the author for the excellent discussions of these 

 most interesting vertebrates, which he discusses and figures so 

 fully and so beautifully. The text of these two chapters is illus- 

 trated with 33 exquisite drawings and photographs based on ac- 

 tual specimens or on the most authoritative works. The writer 

 of these reviews feels a personal debt to Professor Patten for the 

 figures of the left pectoral Limb of Eusthanopteron fordi (Whit- 

 eaves) from the Devonian of Canada. He says of the limb that it 



indicates the way ... in which the typical skeleton of the pectoral 

 appendage of the tetrapoda has been derived from the hiserial pectoral 

 fin of fishes. 



We should like to modify the sentence to say may instead of has, 

 for no one knows whether or not this was the way of the origin 

 of the tetrapodous limb. Restorations of Cepholaspis, Lasanius, 

 Birkenia, Thdodus, Lanarl ia, Vrcpanaspis and Bothriolepis are 

 given, as well as two photographic pages of specimens of Bothri- 

 olepis as they occur in the rock: one slab containing nearly a dozen 

 more or less complete specimens. My means of sections Professor 

 Patten has arrived at some conclusions which seem to point, in 

 his opinion, to the arachnoids. The structures he describes are 

 certainly very interesting in their resemblance to arachnid struc- 

 tures. If his interpretation of their value is doubted he has the 

 satisfaction of knowing that no better interpretation has been 

 given. To say that they are characters due to parallelism is beg- 



