232 



1234. The skull of a small Gull (Larus). Mm. South. 



1235. The hyoidean arch of a small Gull (Larus}. Presented by Dr. Leach, F.L.S. 



1236. The thorax, pelvis, and scapular arch of a small Gull (Larus). 



There are 9 pairs of ribs, the last two heing supported by sacral vertebrae : the first pair is 

 free or floating ; the rest are completed by bony hsemapophyses, all of which, save the last, 

 articulate directly with the sternum : five pairs of these ribs support appendages. Many of 

 the tendons of the dorso-spinal muscles are ossified. 



Hunterian. 



Genus Sterna (Terns). 



1237. The skeleton of a large Tern (Sterna caspia}. 



There are 20 vertebrae between the skull and sternum, the last six of which support move- 

 able ribs, of which the first is free ; the succeeding five are articulated to the sternum by bony 

 hsemapophyses ; the seventh and eighth pairs of ribs are attached to the sacrum, the seventh 

 being articulated to the sternum by bony hsemapophyses, whilst those of the eighth are 

 attached to the preceding ones. There are 9 caudal vertebrae. The pectoral process of the 

 humerus is unusually developed and incurved. 



Hunterian. 



1238. The skeleton of a Tern (Sterna (Thalasseus) poliocercus). 



The number of vertebrae between the skull and the sacrum is 21, of which the last six 

 support moveable ribs, the first sacral vertebrae supporting a similar pair. The keel of the 

 sternum is relatively longer and deeper than in the Albatros or Petrel. The apex of the 

 furculum is attached to a semi-ossified arch or loop, at the fore part of the apex of the keel 

 of the sternum. The pectoral process of the humerus is remarkably developed and incurved ; 

 the ectocondyloid process is also more developed than in the Albatros. There are 8 caudal 

 vertebrse. 



Mus. Gould. 



1239. The skull of the common Tern (Sterna Hirundo}. Purchased. 



1240. The dried head of the common Tern (Sterna Hirundo). 



Presented by W. Bullock, Esq. 



