134 BULLETm UNITED STATES GEOLOGICAL SURVEY. [Tol.VI. 



are also enlarged and laterally flattened for articulation with the verte- 

 bral ribs. These latter enlarged ends are sometimes larger, sometimes 

 smaller, than the extremity of the iDleurapophysis they meet. 



Through the teachings of jDhilosophical anatomy, we must recognize- 

 in the avian haemal spine or the bone sternum, developed as it may be^ 

 the confluent haemal spines ; and in it, in its maturity, see one of the 

 most interesting bones to contemplate, it being one of the most diversi- 

 fied in form in the bird skeleton. Owen styled the type of this bone, as. 

 found in the Lark now under consideration, "cantorial" (Anat. and 

 Phys. of Vert., Vol. III). It is certainly typical of the suborder Oscines^ 

 as far as American ornithology is concerned ; good examples as testify- 

 ing to this I have now before me, in the hsemal spines of Turdus mi- 

 gratorius, AmpeUs garruhts, Mimus polygloUus,Lanius, and many others. 



In UremopMla the sternum is very light and delicate in structure ; so 

 thin is it in some individuals that we fiud deficiencies occurring, usually 

 in the body, as foramina of no mean size (1.8 millimetres). Its outer 

 surface, indeed the entire surface of the bone, has the appearance as if 

 it were venated, the sohd bony veins being thicker and more opaque 

 than the general surface of the bone, and «branching from the various 

 borders. 



The carina is moderately well developed, measuring in the vertical 

 line below the coracoidal groove 9 millimetres. Its inferior border, ex- 

 panded behind, is rounded and somewhat thickened; this thickening: 

 disappears on the anterior border, which is sharper and continuous with 

 a conspicuous crest on the front of the manubrium. 



The carinal angle, with an aperture of 70°, is quite prominent and 

 produced anteriorly. Just within the anterior margin of the keel we 

 find a rather prominent carinal ridge, its lower extremity branching 

 backwards, and by its ramifications taking part in the superficial vena- 

 tion referred to above. The keel arises abruptly from the inferior and 

 median angles formed by the sides of the body where they meet mesiad. 



The xiphoidal prolongation is i^rofoundly notched once on each side. 

 These notches have the outlines of isoceles triangles, with their angles 

 rounded, and apices but a short distance from the costal borders. These 

 deep indentations of the xiphoid give rise on either lateral sternal bor- 

 der to a long, stout process, extending backwards and outwards, with 

 dilated extremity. 



The outer surface of the body of the sternum presents for examination 

 well-marked pectoral ridges, and, running from the bases of the xiphoidal 

 processes to the outer angles of the coracoidal depression, clearly defined 

 subcostal ridges. 



The manuhrium is a prominent, superiorly bifurcated, trihedral process,, 

 jutting out from a substantial base in the median plane, forwards and 

 upwards, from the angle formed by the coracoid groove and the front 

 border of the carina. At its base internally there is an extensive oval 

 pneumatic foramen. Its bifurcations are rounded, and give attachment 



