76 PEOFESSOE OWEN ON THE 



Dromaius and Casuarius, yet the length of those foramina (which are unclosed) in 

 Struthio and Apteryx, concomitant with the greater relative length of the pelvis, shows 

 the difference of iJidus from the cursorial Brevipennates in this part of the skeleton. 

 The ischia of the winged Pigeons resemble those of the Dodo; but the inner longitu- 

 dinal ridge is more strongly marked in Didunciilus : in the Goura it is less developed 

 than in Bidus ; the bone is longer also in proportion to its breadth, and the ischiadic 

 foramen is longer and narrower : the proportions of that in Didimculus are more like 

 those in Bidus. In IHdunculus the pubis coalesces with the ischium behind the small 

 obturator foramen, but leaves a second or posterior elongate ischio-pubic vacuity. The 

 greatest amovmt of resemblances with the pelvis of the Dodo is found in that of different 

 members of the Dove-tribe. 



In comparing the pelvis of the Dodo with that of the Vulture (PI. XXIV. fig. 6), we 

 find in the latter that the fii'st two confluent sacral vertebrae supporting moveable ribs 

 are succeeded by several with short abutting ribs, the extent of this part of the sacrum 

 being nearly one-half of tlie whole, instead of one-fourth as in Didus and the Doves. 

 The reappearance of rib-abutments after four ribless sacrals is in the posterior thu-d of 

 the sacrum, and they are continued to the end of that bone from the last four vertebrae 

 of the series, constituting a very marked difference, both as to number and the character 

 of the vertebrae in the sacral part of the pelvis. 



With regard to the iliac bones, the anterior concave track occupies two-thii-ds of the 

 extent of the bone in Vultur, not one-half as in Didus and most Doves ; the breadth of the 

 posterior parts of the ilia with the intervening sacrum in the Vultiu'e is relatively less 

 than in the winged Doves, and differs in a greater degree from that characteristic part in 

 the sacrum of Didus. In Ciconia the antacetabular part of the pelvis is relatively 

 longer, and the iliac bones are more expanded anteriorly. In Platalea the proportions 

 are more nearly those in Didus. In Otis the ilia touch the fore part of the sacro-spinal 

 ridge, but leave both posterior and anterior apertures of the ilio-neural canals widely 

 open. In (Edicnemus and Charadrius they are grooves, the Uia not reaching the sacral 

 spines. The external concavity of the Uium is longer, narrower, and deeper, in most 

 waders, than in Didus. In Eiidyptes and Ap)tenodytes the ilia are more expanded ante- 

 riorly, but the whole pelvis is narrower and longer than in Didus. The Gar-fowl 

 {Alca impennisy, Uria, Podiceps, and Colymbus, all show still longer and narrower pro- 

 portions of the pelvis. 



In the Doves of flight the proportions and relative position of the three compart- 

 ments of the cranial cavity differ fr-om those in the Dodo. Both the pros- and mesen- 

 cephalic ones are proportionally larger than the epencephalic ; and the mesencephalic 

 compartment lies more directly below the prosencephalic one. A very thin stratum of 

 finely cellular diploe divides the two tables of the skull along the medial line of the 

 upper surface : it is thicker between the orbits. The falcial ridge at the inner surface 



' Trans. Zool. Soc. vol. v. pi. 51. 



