682 GEOLOGICAL SURVEY OF THE TERRITORIES. 
margins are produced slightly outwards, the inferior being the sharper 
of the two. 
The “costal processes” are exceedingly prominent, being bent over 
anteriorly at their apices, which are rounded. Behind them are observed 
the limited “costal borders,” exhibiting the four transverse facets for 
the sternal ribs, and pneumatic foramina. The “ carina” or keel affords 
the greatest amount of osseous surface of the entire bone, greatly ex- 
ceeding the body. Its lower margin is a long convex curve outwards, 
and the ‘ carinal angle” protrudes forwards nearly as far as the manu- 
brium, causing the anterior margin of the keel to be decidedly concave. 
The “earinal ridge” is thickened and heavy superiorly, where it 
limits or rather constitutes the boundary of the bone in that direction. 
Below it spreads out and is gradually lost, within the boundary of the 
earinal border proper. 
‘¢ Subcostal” and “‘ pectoral ridges” are nearly always well defined. 
The superior and inferior xiphoidal processes are very characteristic 
of the Tetraonide. They terminate by dilated extremities of nearly simi- 
lar shapes, Cupidonia being an exception; the ends of the apophyses 
of the superior pair in this bird being rounded posteriorly (Plate XI, 
Fig. 82; see Plate XIII, Fig. 91, Lagopus, forthecommon pattern.) These 
processes arise from a common stem, and their shafts are flat internally, 
with a raised ridge extending the entire length externally. The ‘‘ body” 
of the sternum is, as arule, very narrow, and notably concave anteriorly, 
becoming nearly flat behind, where it is produced beyond the keel for 
a greater or less distance. 
The manner in which this part terminates varies in the different 
Grouse. 
In Centrocercus it is nearly square across; in Lagopus roundly notched _ 
in the middle line, as it is in Bonasa ; in Tetrao canadensis it is broadly 
cordate ; while in Canace obscura, Cupidonia, and Pediecetes it is dis- 
tinctly cuneiform. The body is very narrow in Bonasa, approaching 
the Ortygine, where it seems really to be nothing more than a good 
ribbon-like finish to the superior border of the keel. In these birds, 
too, we are struck with the double carinal margins anteriorly formed by 
the projecting ridges, and the long spicula-form costal processes that 
extend nearly half-way up the shafts of the coracoids. 
So much do the sterna of the Grouse resemble one another in species 
-of average size that it would puzzle one not a little to tell them apart 
if they were separated from the skeleton, and we were not allowed to 
examine them in connection with other diagnostic features of the osse- 
ous parts of the species to which they might belc .y. 
In the Ortygine dilatations at the outer extremities of the xiphoidal 
prolongations are sometimes but moderately developed, as in our speci- 
men of Cyrtonyx massena, and the Plumed Partridge. The dilatations of 
the anterior or shorter pair of these processes are very broad in Meleagris, 
as are the stems that support them; the expanded part may have a 
foramen in it, or it may become bifurcated and the same specimen may 
show both varieties of termination. The longer or posterior pair in this 
Species become very narrow behind, but stouter, and scarcely support 
any terminal expansions at all. The anterior half of the keel of the 
sternum of the Wild Turkey is very thick and strong, and all its ante- 
rior parts are prolonged upwards and forwards, being massive and lofty 
in very old birds. In other respects the sternum is stamped with the 
leading features of the bone as found among gallinaceous fowls generally, 
and this remark applies also to the sterna of Pavo cristatus and Numida. 
Cupidonia and Pedicecetes are particularly alike, but the former could 
