Shufeldt: Birds from Bermuda. 371 



perhaps the exception of the last pair, and there was probably a pair 

 of free cervical ribs. 



The vertebrae and ribs in the collection of the American Museum 

 of Natural History do not fully admit of completing the chain, in 

 order to assemble a perfect skeleton of ^strclata vocifcrans, while 

 they do in the collection of Mr. McGall. After very careful study, 

 I have selected from the latter lot a string of vertebrae that I must 

 believe are very nearly, if not quite, correct. They may, of course, 

 have belonged to a number of different individuals, and are probably 

 of both sexes at different ages; but this is the very best one can do 

 with such a mixed lot of material. In my own mind there is no 

 question but that the number of vertebrae in the spinal column of the 

 extinct Petrel here considered agreed with " CEstrclata grisea," as 

 enumerated above ; so, too, for the ribs. One thing is certain : both 

 species possess eleven vertebrae in the sacrum. Then I selected the 

 cervico-dorsal series before I turned to the work of Forbes on CEsfre- 

 lata grisea, and very much to my satisfaction I found that I had 

 settled upon the same number of cervicals and dorsals that he had 

 entered in his table — that is, 15 cervicals and 7 dorsal vertebrae. The 

 arrangement is precisely the same throughout — ribs, epipleural ap- 

 pendages, and all — in Ossifraga gigantea as it is in the true petrels, 

 but not in any of the rest of the Procellaridcr, in so far as Forbes 

 and I have examined them. 



The atlas is very delicately fashioned, its body being incomplete 

 above, the remaining parts either thin or small, and the bone is un- 

 marked by any passage on either side for the vertebral arteries. This 

 is also the case with the axis, in which vertebra the odontoid process 

 is short and feebly developed. It has, however, a well-pronounced 

 haemal and neural apophysis, and its diapophyses are turned abruptly 

 upwards. 



We find that the third cervical vertebra also possesses strong neural 

 and haemal spines, while perfect canals for the vertebral arteries are 

 present in it, and short pleurapophyses project backwards from be- 

 neath them, one upon either side. These are longer and more spiculi- 

 form in the fourth cervical, and in this the pre- and postzygapophyses 

 are an evident feature. Its neural and haemal spines are on the road 

 toward aborting. From this point on, to include the 15th vertebra 

 which supports a pair of free ribs, the vertebrae of this division of 



