180 



PROFESSOR 0"W"EN ON THE GENUS DINORNIS. 



en charrue,' or ' ploughshare bone,' in most other birds, and in all those that fly and 

 possess the ' rectrices ' or ' rudder-feathers,' as the tail-quills are termed. 



In the description of the skeleton of Dinomis ele])]ia)ifopus ^ nine caudal vertebrae 

 are noted, as in the Apteryx, reckoning the terminal bone as one of the series, and its 

 leading distinction of shape from that in birds of flight is pointed out. The character 

 of the bifid neural spine is indicated as " a pair of tubercles supported by a low trans- 

 versely extended neural arch " ^. 



FORTY-SIXTH, FORTY-SEVEJ^TH, and FORTY-EIGHTH VERTEBRA, or Terminal Caudals 



(j nat. size). 

 Fig. 38. Fig. 39. 



Aspects. 

 Fig. 38, lateral ; 39, hjemal. 



In a species of Dinomis, which Capt. Hutton thinks may be I), crassus ^, the last 

 three caudal vertebrae coalesce into the 'ploughshare bone ' (figs. 38 & 39); but this, as 

 in D. elephantopiis, B. maximus, and doubtless in the rest of the genus, has no claim 

 to the shape, common in birds, which suggested the vernacular name ■*. 



The neural spine is suppressed in the last two of these caudals (fig. 38, 8, y), which 

 are reduced to the central element with, perhaps, a neural ridge imperforate ; and this 

 ridge forms the uppermost of the three ridges which characterize the three-sided cone 

 constituted by these two terminal vertebra;. Of the three sides the lower is the 

 broadest (fig. 39, 9). 



In the penultimate (8th caudal) vertebra the lower surface (ib. s) presents a tri- 

 angular excavation, the base being turned forward and the sides formed by the last 

 rudiments of parapophyses (ib. 8, 9, p, p) ; the apex of the ca\aty extends to the 

 anchylosis with the last vertebra. The sides of both vertebrae are subconcave, the 

 centrum expanding at both ends. The 5Mas?-parapophysial expansions of the fore end 

 of the last centrum (ib. 9, p) extend beyond the hinder expansions of the penultimate 

 vertebra. The centrum of the last vertebra contracts to an obtuse point, grooved below. 



' Zool. Trans, vol. iv. p. 163. ' Ib. 



' " The box also contains a complete set of caudal vertebras of D. crassus (?) from Shag Point : these are from 

 one bird." Letter dated " Dunedin, N.Z., 13th Dec. 1875." These vertebrae were six in number, reckoning 

 the soldered three as one. I doubt their including the entire series. 



* ' Os en charrue,' Fr. 



