SHUFELDT : OSTEOLOGY OF THE STEGANOPODES 207 



ments, the ceratobranchials are long, slightly curved, and completely ossified ; the 

 epibranchials are in cartilage only. In my specimen the sderotals of the eye, and 

 the bony elements of the internal ear, are missing. 



Of the Remainder of the Axial Skeleton. 



Upon examining the vertebral chain of Fregata aquila we find in it thirteen 

 vertebrae in the cervical region, that do not support free ribs ; the fourteenth 

 vertebra has a long, slender pair that are without unciform processes, the next five, 

 all freely movable upon each other, connect with the sternum by means of their 

 costal ribs or haemapophyses ; then, finally, there are two pairs of pelvic ribs, but 

 it is only the costal ribs of the leading or anterior pair, that connect with the 

 sternum. In the specimen before us, we may call them, from the fifteenth to the nine- 

 teenth vertebra inclusive, true dorsals, while counting, as best we may, the number 

 of vertebrae fused together in the pelvic sacrum, there appear to be fourteen in all. 

 Next follow six free caudals and a large pygostyle. 



Since the first part of this memoir was written I have had placed before me, a 

 skeleton in the rough of the Great Wandering Albatross (D:exulans), and upon com- 

 paring the arrangement and number of its vertebrae with what has just been given 

 for Fregata, we find it to be dissimilar in many particulars. This leads me to think 

 that with respect to the spinal column, the ribs, and the vertebrae, no typical Alba- 

 tross will be found to agree with the Man-o'-War Bird. 



Pneumaticity is a prominent character of the trunk skeleton of Fregata, and it 

 would seem that all the bones enjoyed that state. The atlas has a broad neural 

 arch, and its cup instead of being perforated, is extensively notched above. On the 

 axis the "odontoid process" is short and stumpy; and its haemal spine is also an in- 

 significant affair. On the dorsal aspect of this vertebra, the neural spine is broad 

 and tuberous, while the postzygapophysial processes are much swollen also. These 

 latter, in the third vertebra, are joined upon either side with the prezygapophyses 

 by means of a somewhat delicate interzygapophysial bar. A large haemal spine is 

 present here, and a low neural one. The same character is to be found in the fourth 

 vertebra, and both third and fourth possess short backward-projecting parapophysial 

 spines. 



In the fourth or fifth cervical a distinct neural process exists ; it is absent again 

 to include the ninth vertebra; it is but faintly developed in the tenth, and from 

 thence backward it gradually increases in proportion and changes in form, until we 

 have the low, quadrate plate of the dorsal series. Throughout the latter, haemal 

 spines are absent, and from the fifth to the tenth vertebra inclusive, the carotid 



