OSTEOLOGY OF THE DODO. 73 



would have had eight pairs of thoracic ribs ; and I think this excess of one pair beyond 

 the formula in Didunculus to be very probable in the large-bodied, small-winged extinct 

 Ground-dove. 



As far as the series of Dodo's neck-vertebrse under my observation exhibit such 

 characters, the proportion of those with neural spines, or with hypapophyses, or both, 

 is the same as in the ColumMdce. In this family, as in most birds, the greater part of 

 the series want both processes. The cervical parapophyses, descending to form the 

 sides of the carotid canal, do not meet, coalesce, and circumscribe it in any cervical 

 vertebra of Goura or Didunculus ; and not any of the vertebrae of Didus, which I have 

 yet received, shows such circumscription of the hsemal canal. The majority of the 

 cervicals in Didus (those, viz., that lack both neural spines and hypapophyses) are 

 broader and more massive in proportion to their length than in the winged Doves. The 

 third cervical m Didus has both the above processes, as in Columlidw : the characters 

 of the axis vertebra in the same family are closely repeated in that of the Dodo. In 

 the Raptores the axis vertebra is shorter in proportion to its length, and a greater pro 

 portion of the cervical vertebree at both ends of the series have both neural spines and 

 hypapophyses. 



The ribs of the Dodo are as broad, in proportion to their length, as in Doves, but are 

 relatively longer in proportion to the dorsal region-, encompas.sing a more capacious 

 thoracic-abdominal cavity. The ribs of the Vulture are more expanded than in Didus, 

 especially where they afford the extensive attachment to the epipleurals. But I shall 

 not dwell further on the comparative characters of this part of the skeleton, as more 

 decisive ones of the affinity of Didus are afforded by other parts. 



In comparing the sternum of the Dodo with that of Doves of flight, the first well- 

 marked difference is in the adaptive development of the keel in the last (PI. XV. fig. 2, 

 Didunculus), and in the provision for the concomitantly broader coracoids, the grooves for 

 which meet and run into each other across the fore part of the bone in existing Colum- 

 bidm (PI. XXIV. fig. 2, b) ; consequently the inner or upper wall of the confluent grooves 

 forms a median prominence (ib. e) at the front margin of the sternum, contrasting with 

 the wide notch at that part of the bone in the Dodo (PI. XVI. fig. 4). The next differ- 

 ence, as compared with Goura and most Pigeons, is the absence of the entolateral 

 processes (PI. XXIV. fig. 3, i) in the Dodo's sternum : but Didtmculus singularly exem- 

 plifies its nearer affinity to Didus by a like absence of those processes ; only the sternal 

 margins behind the ectolateral processes (ib. fig. 1, h), instead of converging with a 

 slight convexity to an obtuse apex, as in PI. XVIII., describe a concavity, through an 

 expansion of the posterior truncate end of the breast-bone. The sternum oi Didunculus 

 may be said to show one pair of posterior notches (PI. XXIV. fig. 1,/), that of other 

 Pigeons two pau-s(ib. fig. 3,//') ; but the sternum of Didus, vfhich is relatively broader, 

 shows no other trace of the anterior notch (PI. XVIII. /) than is afforded by the 

 rounded angle at which the ectolateral process (h) rises from the bone. Although the 



VOL. VI. PART 11. ^ 



