219 
the entire bone, as shown in the subjoined admeasurements, is longer in the Din, gracilis: 
it is also, as the name of the species implies, more slender in proportion to its length. 
This bone (Pl. LV. fig. 1) was obtained from beneath a sandy deposit, about two 
feet below the surface, at a locality between Wanganui and Turakina, North Island of 
New Zealand, by the Rev. Mr. Taylor. 
D. gracilis. 
in. lin. 
The entire length of the bone is . . . . . . 23 6 
The transverse breadth of its proximalend . . 5 O 
The transverse breadth of its distal end aa Be 
The circumference of the middle of the shaft. . 4 
The fibular ridge extends down the shaft 9 
10 
6 
6 
But this ridge commences nearly three inches below the back part of the proximal 
end of the bone, nearer the outer side than in the D. struthioides : it is interrupted by 
an oblique smooth tract at the point indicated in the admeasurement, where the 
medullary artery penetrates the bone ; it then reappears about an inch and a half below 
the interruption, and soon gradually subsides. This second lower part of a fibular 
ridge is better marked than in the Din. struthioides. The relative size and position of 
the procnemial, p, and ectocnemial, e, ridges are much the same as in the tibia of the 
Din, struthioides and Din. dromioides. 
Metatarsus (Pl. LIV. fig. 3). 
The difference between the Din. struthioides and the Din. gracilis is more obvious at 
first glance in a comparison of their metatarsi than in that of the above-described bones ; 
especially to an eye accustomed to the comparison of the metatarsi of the different 
species. The superior length and slenderness of that bone in the Din. gracilis would at 
once prevent its being confounded with the metatarsus of the Din. struthoides. 
The following are the chief dimensions of the bone in question: those of the extre- 
mities being approximative by reason of their worn margins :— 
D. gracilis, 
in. lin. 
Length of the tarso-metatarsus . . . . - + Is 
Circumference at the middle of the shaft : 
Transverse breadth of proximal end 
Transverse breadth of the distal end 
Breadth of the middle of the shaft 
Thickness or antero-posterior diameter of ditto 
ae OO 
mon ® & & OS 
The depressed surface for the back toe is better marked than in the Din. struthioides, 
