178 ON A DUCTUS BOTALLI IN CERTAIN BIRDS. [Feb. 17, 



The appearance of the abnormal vessels in the other specimen, 

 a Chilian Pintail {Dafila spinicauda), though the abnormality was 

 essentially the same, was less striking ; the right carotid ran towards 

 the left as in the Heron, for a short distance, but seemed relatively 

 smaller and straighter ; but it similarly turned suddenly forwards, 

 at the point of giving off the vertebral, and sent a vessel backwards 

 to the dorsal aorta, which it joined, at the left side of it opposite 

 the base of the heart. This specimen was not injected, but I was 

 able, by passing a bristle down the tube, to satisfy myself that the 

 connection between the carotid and the aorta was a functional one. I 

 also noted that in this specimen the artery supplying the skin of the 

 neck sprang, on the right side, from the same point as the vertebral, 

 while on the left it was smaller and given off a little posteriorly to 

 the vertebral. A ductus arteriosus stretched from the left side of 

 the dorsal aorta to the left pulmonary artery. Professor G. B. 

 Howes has kindly drawn my attention to Professor Turner's paper 

 on Globiocephalus svineval (Journ. Anat. & Phys. ii. p. 66, 1868), in 

 which the existence of a closed ductus arteriosus between the aorta 

 and pulmonary artery is recorded as occurring in that Cetacean. 

 Messrs. Marshall and Hurst also mention it in the Rabbit. 



Although I have dissected examples of upwai'ds of 90 species, the 

 above is the only abnormal variation in the carotids which I have 

 observed ; and that in the two specimens in which it occurred it can 

 only be regarded as an individual peculiarity I have had ample oppor- 

 tunities of proving, having dissected three other specimens of Nyc- 

 ticorax violaceus and one other of Dqfila spinicauda, besides two 

 specimens of Nycticorax griseus and one of Dafila bahamensis, none 

 of which exhibited this abnormality. I find, too, that the late 

 Prof. Garrod has examined the three first-named species, besides 

 Nycticorax caledonicus, and has not recorded any abnormality in 

 their carotids. 



It would seem therefore that this approach to the reptilian 

 structure does not characterize any particular species or genus, but 

 is liable to appear sporadically in individual specimens of species 

 belonging to widely separated groups. 



In conclusion, I have to express my thanks to the Society for the 

 facilities for study which they have afforded me, and in particular 

 to their Prosector, without whose kind tuition and assistance this 

 communication would have been impossible. 



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