1907.] ox THE AZYGOS VEIXS IN MAMMALS. 181 



the characters of the upper side would be reproduced in the lower^ 

 both pigmentation and armature. The symmetry does not extend 

 to the eyes and skull, but then the malformation of the head may 

 be due to a partial symmetiy, a reduction of the normal asymmetry. 



It is possible that both cases occur in different specimens — that 

 is to say, that in some ambicolorate specimens the condition is 

 due to metastrophe of the posterior i-egion of the body ; in others 

 to secondary symmetry, the doubling of the upper side in the 

 gamete. This cannot be decided without further investigation of 

 abnormal specimens both in the young state and the adult. There 

 can be no doubt of the importance of the unique condition 

 exhibited by the specimen heie descinbed, or that its condition 

 is best explained on the view I have suggested, namely, that it 

 consists of a metastrophic head joined to a normal body. 



I beg to ofier my thanks and congratulations to Miss Fox and 

 Mr. Enys for making the specimen known, and my thanks to 

 Dr. Allen for allowing me to describe it. 



EXPLANATION OF PLATE XI. 

 Abnormal Young Turbot. 



Fig. 1. Right (upper) side of abnormal Turbot 4'4 mm. long, enlarged. The eyes 

 are on the right side of the head, and the dorsal fin projects anteriorly as 

 a free process. Some pigment on the head dorsally, elsewhere only 

 scattered black chromatophores. 



Fig. 2. Left (lower) side of the abnormal Turbot shown in fig. 1. No ej'es on 

 the left side of head, nor pigment. Pigment on the posterior region as in 

 normal specimen. 



4. On the Azjo-qs Veins in the Mammalia. By Feank 

 E. Be-DDARd, M.A. (Oxon.), F.R.S., Prosector to the 

 Society. 



[Received February 1 , 1907'.] 



(Text-figures 62-73.) 



COXTENTS. 



(1) Introductory, p. 181. ] (9) The Azygos and other thoracic veins 



(2) TheAzygosVeinsintheUngulata, i» ^lie young of Ilyopotamus 



n 183 coypH,y).2l^. 



^' ' : (10) The condition of the Azj'gos and 



(3) Insectivora, p. 196. 



(4) Lemurs and Apes, p. 197 



(5) Edentata, p. 198. 



(6) Carnivora, p. 198. 



(7) Marsupials, p. 200. 



(8) Rodents, p. 208. 



the Classification of Maranials,. 

 p. 218. 



(11) The position of tlie Azygos witli 



reference to tlie Vertebrae, p. 219. 



(12) The Venie Intercostales Supremie,. 



p. 221. 



(13) Conclusions, p. 222. 



(1) Introductory. 



It appeared to Cuvier* — and presumably to his editor Duvernoy,, 

 since the statement is left unannotated — that the Azygos veins in 

 mammals were too variable to offer zoological characters of value \ 



* Anat. Comp. ed. 2, t. vi. (Paris, 1839) p. 238. 



