AORTIC ARCHES OF BIRDS — GLEiSTNY 



557 



Species studied 



Oceanodroma leucorhoa (Vieillot) 

 Oceanodroma macrodactyla W. E. Bryant 

 Oceanodroma monorhis socorroensis C. H. 



Townsend 

 Oceanodroma hornbyi (G. R. Gray) 

 Halocyplena microsoma Coues 



By Garrod 



Thalassidroma pelagica= Hydrobates pe- 

 lagicus (Linn6) 



Thalassidroma fregata= Pelagodroma ma- 

 rina (Latham) 



By Glenny 



Oceaniies oceanicus (Kuhl) 

 Oceanites gracilis galapagoensis Lowe 



Fam% Pelecanoididae 



Ligamentum aortae prominent; ligamentum botalli lacking or re- 

 duced to a linea botalli; vertebrals and cervicals usually arise sepa- 

 rately from the common carotid; superficial cervicals variable, but 

 usually two pairs are present. 



In Pelecanoides exsul the ligamentum aortae may present a lumen 

 for a short distance. The left dorsal carotid alone enters the hypapo- 

 physial canal in Pelecanoides garnotii (USNM 344806) : B-4-s. 



Species studied 

 By Glenny 

 Pelecanoides exsul Salvin (2) j Pelecanoides garnotii (Lesson) 



Order PELECANIFORMES 



Both bicarotid and unicarotid arrangements occur within the order; 

 type A coracoid artery; type 1 thoracic artery except in Morus 

 bassanus (type 2 or type 3); hgamentum aortae present; ligamentum 

 botalli either present or absent; origin of vertebrals and superficial 

 cervicals variable. 



Reference: Garrod, 1873. 



Family Phaethontidae 

 Carotids A-1 ; presence of ligamentum botalli variable. 



Species studied 



By Glenny 



Phaethon lepturus dorotheae Mathews 

 Phaeihon rubricauda rothschildi (Math- 

 ews) 



By Garrod 



Phaethon sp. 



Family Pelecanidae 



Carotids B-3b-d; ligamentum botalli generally present. 



The unicarotid condition in this family is clearly a further step in 

 the modification of the conjugate carotid condition of the dorsal 

 carotid arteries. 



3.S2543— 53- 



