No. 4.] SIIUFELDT ON THE OSTEOLOGY OF SPEOTYTO. 103 



and tlie diapopliyses are strong and raised, with their enlarged extrem- 

 ities expanded upon and firmly united with the iliac bones. There is but 

 one pair of sacral pleurapophyses, and they are free ones. Long and 

 slender, they articulate with the first vertebra in the usual manner, but 

 the relation is much more intimate, as they touch the diapophyses for 

 some little distance beyond the tubercula towards the capitula. The 

 lower extremities of these ribs are terminated by little roundish knobs, 

 which articulate with the hfemapophysis on either side, described as 

 being inserted in the posterior border of the fifth sternal rib. View- 

 ing the bone dorsal-wise, it is to be seen that the thickened crest of the 

 neural spine of the first vertebra protrudes from the angle made by the 

 ilia meeting it anteriorly to a greater or less distance. This broad and 

 compressed crest, then continued backwards, is firmly wedged between 

 the ilia until we pass the third vertebra ; at this point the ilia diverge from 

 each other to another point just anterior to the acetabula, then converge, 

 terminating in the posterior sacro-iline border within five or six milli- 

 metres of each other. The sacrum completely fills in the lozenge-shaped 

 space thus formed from the third vertebra — first, by continued broaden- 

 ing and compression of the neural spine, that soon becomes one with the 

 neurapophyses ; and, secondly, by the expanded extremities of the di- and 

 par-apophyses, the processes themselves also taking due part. The integ- 

 ritj" of the surface is unbroken, save posteriorly, where a few pairs of fora- 

 mina exist among the expanded transverse processes, increasing in size 

 from before backwards. Anterior to a line joining the acetabula this 

 surface is in the horizontal plane ; posterior to this line there is a decline, 

 which declination is accepted also by the innominate bones ; this gives 

 the entu'e pelvis a shape that seems to be characteristic of the majority ot 

 both the diurnal and nocturnal Raptores. The '^ ilio-neural" canals here 

 present open by small apertures posteriorly, at about the point where 

 the ilia commences to diverge, passing obliquely downwards and for- 

 wards; their anterior openings are large enough to allow a view of their 

 internal walls. The neural spine that divides them throughout is com- 

 pressed from side to side ; the ilia which form their outer boundaries are 

 convex; the neuro-spinal crest forms the roof, the basal surface being, 

 deficient, formed merely by the spine-like di- and par-apophyses of the 

 vertebrae and the confluent neural arches. The first vertebra occupies 

 the lowest level, the bird supposed to be standing as in PI. I. Xow, a 

 line drawn mesial on the centra below, from the first centrum to the last, 

 gradually rises until opposite the anterior borders of the ischiadic fora- 

 mina, then curves rather abruptly downwards to its termination. The 

 centra of the first two or three vertebrne are compressed from side to side 

 to such an extent as to cause them to appear wedge-shaped, the common 

 apex or edge being below ; after that, however, they rapidly broaden, 

 become compressed vertically and more cellular in structure ; they are 

 very broad from the fourth to the ninth, inclusive — then as ra])i<lly be- 

 come contracted as they approach the coccyx. Minute but numerous 



