180 PROFESSOR OWEN 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 Dinornis elephantopus! nine caudal vertebre 
are noted, as in the Apteryar, 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- 
2 
versely extended neural arch” ’. 
FORTY-SIXTH, FORTY-SEVENTH, and FORTY-EIGHTH VERTEBRA, or Terminal Caudals 
(3 nat. size). 
Fig. 39. 

Aspects. 
Fig. 38, lateral ; 39, hemal. 
In a species of Dinornis, which Capt. Hutton thinks may be D. crassus*, the last 
three caudal vertebree coalesce into the ‘ ploughshare bone’ (figs. 38 & 39); but this, as 
in D. elephantopus, D. 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, 9), 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. 8) 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 cavity extends to the 
anchylosis with the last vertebra. The sides of both vertebre are subconcave, the 
centrum expanding at both ends. The quasi-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.iy. p. 163. 2olibs 
8 « The box also contains a complete set of caudal vertebrae 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. 
4 ¢ Os en charrue,’ Fr. 
