REPOET ON THE SPHENISCID^. 17 



ception of those of the eleventh and twelfth, are fused with one another, as well as with 

 those of the last dorsal vertebra, to form an osseous margin for articulation with the 

 innominate bone. The intervertebral foramina, with the exception of those between the 

 eleventh and twelfth vertebrae, are completed by the vertebrae themselves. Those 

 between the eleventh and twelfth lumbo-sacral vertebrae are of larger size than the 

 others, and are completed externally by the pelvic bone. The renal fossae are deep and 

 oval in form. They are separated from one another by the median ridge formed by the 

 fusion of the vertebral bodies. 



The articular processes, spinous processes and arches of the lumbo-sacral vertebrae, 

 together with those of the last dorsal vertebra, unite to form a single osseous mass. 

 The spinous processes form a single continuous osseous ridge, on either side of which 

 lies the portion of bone formed by the union of the arches of the lumbo-sacral vertebrae. 

 This portion is oval in form, its widest part being situated immediately in front of the 

 acetabulum. It is perforated at regular intervals by small foramina, by means of which 

 the dorsal branches of the lumbo-sacral nerves escape from the vertebral canal. 



The distinction between the lumbo-sacral and coccygeal vertebrae is by no means well- 

 defined. In several specimens of different species I found that the first coccygeal 

 was immovably anchylosed with the last lumbo-sacral vertebra, and that the apices 

 of its transverse processes came into contact with the pelvic bone. In every specimen, 

 however, there was a distinct want of anchylosis between the arches and spinous processes 

 of the last lumbo-sacral and those of the first coccygeal vertebra, and this, coupled with 

 the fact that in the majority there was also a certain degree of mobility between the 

 bodies of these vertebrae, while those of the other lumbo-sacral vertebrae were immovably 

 fused together, and that the total number of lumbo-sacral and coccygeal vertebrae together 

 was the same in every species, seems to me to justify the separation of the two segments 

 on the grounds above mentioned. 



The only variation in respect of the lumbo-sacral vertebrae from the arrangement 

 above described in Eudyptes chrysocome, appears in Pygosceles tceniatus. In every pther 

 species the spinous processes of the anchylosed vertebrae form a sharp prominent keel, 

 which extends along the whole length of the lumbo-sacral region. In Pygosceles, on 

 the other hand, this keel presents a flattened appearance, as if the spinous processes 

 had been compressed from above downwards, and appears as a flattened and but 

 slightly prominent surface of bone of an elliptical form, which presents its greatest 

 breadth opposite the sixth lumbo-sacral vertebra, and narrows to a poipt at either end. 



Comparative JReinarks. — ^The lumbo-sacral portion of the^^ertebral column in the 

 Penguins difi"ers, as is well known, from that of other birds, inasmuch as it never 

 becomes completely anchylosed with the pelvic bones. Even in the adult the original 

 separation is indicated by the presence of a well-defined suture. 



(ZOOL. CHALL. EXP.— PART SVIII. — 1883.) S 3 



