354 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [YolTI. 



vertebral canal commences in the tenth — i. e., in this segment it is com- 

 pletely surrounded by bone, and continues its course through the axis ; 

 the last two or three vertebrae are very broad from side to side, the ulti- 

 mate one bearing a free pair of pleurapophyses that have in their turn 

 distinct uncinate processes. 



The neural tube as found in this section of the spine commences and 

 terminates broadly and transversely elliptical, merging into the sub- 

 circular as it nears its mid-portion at the middle of the neck ; it is of 

 considerable caliber throughout. The dorsal division of the spine has 

 allotted to it five vertebrae, closely locked together, yet easily detached 

 by ordinary maceration ; their combined neural spines form one con- 

 tinuous quadrate crest. These are fastened together above by the 

 " arrow-head" point that we have described in other papers. There is very 

 little difference in the lengths of the transverse processes, from first to 

 last, so we do not find much change in the processes of the ribs they 

 sustain, as to length of pedicles and tubercula. Short metapophysial 

 ridges are found above the diapophyses; they never seem to attain 

 sufficient length to connect the vertebral segments, however. 



The neural canal commences transversely elliptical, to terminate, much 

 diminished in caliber, in the subcircular form. In the first dorsal we 

 find a thin quadrate lamina of bone, projecting downwards aud forwards 

 in the mesial plane, as a well-developed hypapophysisj the second sup- 

 ports the merest apology for this process, and the remaining dorsals have 

 none at all, though by compression of the centra a low ridge presents 

 itself along their middles, which is only faintly perceptible in the last. 

 There is a free pair of ribs for each dorsal vertebra, and these are mov- 

 ably connected with the sternum by corresponding pairs of hsemapophy- 

 ses, the whole structure and appearance being distinctly oscine in char- 

 acter. The pleurapophyses are very slender below and not markedly 

 expanded above as they are in some other birds. Commencing with the 

 last cervical rib, and continuing entirely through the dorsals, we find the 

 series of epi-pleural appendages complete on either side, and freely artic- 

 ulated with the posterior borders of the ribs, with which they make an 

 angle of about 45°, and attain sufficient length to overlap the rib in their 

 immediate rear, though often in younger birds, aud even some old ones, the 

 last uncinate process does not reach the free sacral rib. The sternal ribs 

 are quite delicately fashioned, and support, as usual, anteriorly the trans- 

 verse heads for articulation with the costal border of the sternum, while 

 posteriorly we discern the moderately upturned and clubbed extremities 

 with shallow facettes for the inferior ends of the vertebral ribs. 



The sternum of the Loggerhead Shrike is almost or quite typically 

 "cantorial" in its outlines, but only feebly pre-eminent in those features 

 that stamp it as belonging to a bird of any great power of flight. The 

 manubrium, directed upwards and forwards, springs from a solid base to 

 become bifurcate at its anterior extremity and throw down a sharp 

 border below, that becomes continuous with the cariual margin in 



