18/6.] ON THE ANATOMY OF PLOTUS ANHINGA. 335 



skin had been destroyed by moth. The present was therefore the 

 first authentic introduction of the Surnia ulula into this country. 

 The Hawk-Owls of America and Europe were, Mr. Sharpe said, 

 scarcely distinct species, but tolerably recognizable races. 



Tne following Papers were read : — 



1. Notes on the Anatomy of P/o/r<* a«Af«^a. By A. H. 

 Garrod, M.A., f .Z.S., Prosector to the Society. 



[Received March 31, 1876.] 



(Plates XXVI., XXVII., XXVIII.) 



The Darter is one of those birds whose anatomy, with the 

 exception of its skeleton, is comparatively little known ; I therefore 

 take the present opportunity of describing the organs and some 

 of the most important muscles of Plotus anhinga from the two 

 specimens which were recently living in the Society's collection, and 

 which, from my prosectorial advantages, it has been my good 

 fortune to be able to dissect. 



On December 28th, 1872, the Society became possessed, for the 

 first time, by purchase, of a male specimen of Plotus anhinga, 

 which died on the 17th of this month, with general jaundice and 

 distention of the gall-bladder from obstruction of the common bile- 

 duct. Tbe second specimen, a female, was purchased on the 30th 

 of September, 1875 ; it was never quite healthy, and died on the 

 7th of February, without any special organic lesions, but with a 

 dropsical condition of the subcutaneous areolar tissues, frequently 

 found in Steganopod birds. It is this second specimen which I 

 first dissected ; and the other coming to hand, opportunely for me, 

 has enabled me to verify my observations. 



Pterylographically, there is nothing for me to add to the results 

 arrived at by Nitzsch*. The skin is not in the least pneumatic, in 

 which respect it contrasts greatly with Sula and Pelecanus, and 

 agrees with Phalacrocorax. 



With reference to the anatomy of its circulatory organs, it is to 

 be noted that Plotus anhinga possesses only a single carotid artery, 

 the left. In Sula bassana, Phalacrocorax carbo and P. lugubris, 

 Fregata aquila, and Phaethon there are two. In Sulafusca (a speci- 

 men in very bad immature plumage from Port Lemon, Porto Rico) 

 the left carotid only exists, as also in Pelecanus rufescens and P. 

 onocrotalus. 



As to the respiratory organs, from Plate XXVIII. fig. 3 it can 

 be seen that the syrinx is in no way peculiar, a single pair of intrinsic 

 lateral muscles being present. By the side of it I have figured the 

 lower portion of the windpipe of a male Gannet {Sula bassana), in 

 which a pair of fatty bodies are developed just above the bifurcation 

 of the bronchi, the like of which I have not elsewhere seen. 



* Pterylography, Rav Society's Translation, edited bv P. L. Sclater, F.R.S., 

 p. 151. 



