208 



GENERAL ORNITHOLOGY 



n^i 



"bodies, till the last ones are quite down to the level of the ventral 

 aspect of the centrum ; these are also commonly the stoutest, most 

 directly transverse, and most nearly horizontal of the series of pro- 

 cesses, abutting against the ilia a little in advance of the socket of 

 the thigh-bone. This ends a series of consolidated " sacral " verte- 

 bras which are termed collectively " dorso- 

 lumbar," — all of them anterior to the 

 true sacrum of a bird. The sacrum proper 

 (Fig. 57, s) consists of those few vertebrae 

 — three, four, or five — from foramina be- 

 tween which issue the spinal nerves that 

 form the network called the sacral plexus. 

 These true sacral vertebrae are ribless, and 

 may be recognised, in a general way, by 

 the absence of anything like the cross-bars 

 above described, issuing from the verte- 

 bral centra ; though their neural arches 

 send off some small bars or plates to fuse 

 with the ilia. These sacrals proper are at 

 or near the middle of the whole sacral 

 mass. After these come a large number 

 — from five to ten or more — of vertebrae 

 which, from their following the true 

 sacrals, though consolidated therewith 

 and with one another, are considered to 

 belong to what would be the caudal 

 region of other animals, and are hence 

 called " tail-sacrals," urosacrals (Gr. odpa, 

 tail. Fig. 57, c). These continue to send 

 off a series of little plate-like processes 

 from their neural arches, just as the true 

 sacrals do ; l)ut, in addition to these, pro- 

 cesses are given off from the bodies of 

 the urosacrals, corresponding in position 

 and relation to those which proceed from 

 the bodies of the lumbars, and being ap- 



FiG. 57. — The sacrarium of a 

 young fowl, seen from below, nat. 

 size; after Parker, dl, dorsolum- 

 bar series, whereof the first is dor- 

 sal proper, the next three are lum- 

 bar ; s, the sacral series proper, or 

 true sacrum, consisting of five 



l^Z^^'o^J^^^:^^^ parentlyof thesame morphological char- 

 number, which anchyiose with one g^^^gj. (pleurapophvsial). These " riblets " 



another and with the sacrum. \i • t i 



are, however, quite slender, and also 

 oblique in two directions ; for instead of being transverse and 

 nearly horizontal, they trend very obliquely backward and 

 upward ; they also shorten consecutively from before back- 

 ward. The cross - bars of the latter urosacrals, however, are 

 stouter and altogether more like those of a lumbar vertebra. 

 The appearances described are those seen from below, or on 



