264 



lary) (21) at the other end, and they also support the constant element of the diverging 

 appendage of the arch (pterygoid). The hsemapophysis (maxillary) (21) resumes in birds 

 more of its normal proportions and elongated slender form : but the haemal spine (premaxil- 

 lary) (22) is largely developed though undivided, and sends upwards and backwards from the 

 part corresponding to the symphysis of the spine, when this element is divided, a long 

 pointed process ('), which joins and usually coalesces with the neural spine (u) and divides 

 the anterior outlet of the haemal canal into two apertures called the nostrils. The modifica- 

 tion of the haemal arch of the nasal vertebra in the Lizard tribe is here repeated. The 

 pleurapophysial appendage (pterygoid), 24, connects the palato-maxillary arch with the tym- 

 panic, and in the Ostrich and a few other birds, also with the basisphenoid 5 : the second or 

 haemapophysial ray of the diverging appendage (malar and squamosal) is developed in all 

 Birds as in the squamate Saurians ; combining the movements of the haemal arch of the 

 nasal vertebra with that of the frontal vertebra, and consisting of the two styliform ossicles 

 'malar u and squamosal 27) which extend from the haemapophysis, 21, 21", to the pleurapo- 

 physis, is : the essential relationship of the compound ray, w and 27, with the nasal vertebra, 

 is indicated by their becoming confluent with its haemapophysis (at *"), whilst they always 

 maintain an arthrodial articulation with the pleurapophysis (29) of the succeeding vertebra. 



The bones of the splanchno-skeleton intercalated with the segments of the endoskeleton in 

 the bird's skull are the petrosal (IB), between the neural arches of the occipital and parietal 

 vertebrae, early coalescing with the elements of those vertebrae with which it comes in con- 

 tact ; the sclerotals (17), interposed between the frontal and nasal neural arches ; and the 

 thyrohyals (47), retained in connection with the debris of the haemal arch of the parietal 

 vertebra. The olfactory capsule remains cartilaginous. The dermal bone (lacrymal, 13) is 

 well-developed and constant : a second supraorbital dermal bone is occasionally present. 



Purchased. 



1365. The skull of a young Ostrich (Struthio Camelus). 



It shows the principal sutures of the cranium, the bones of which are numbered according 

 to the TABLE or SYNONYMS. 



Hunterian. 



+ 



1366. The thorax, pelvis, and scapular arch of the same young Ostrich. 



It shows the ligamentous condition of the clavicles : the halves of the sternum, which are 

 ossified from distinct centres, are still separate : the distinction of the coracoid from the 

 scapulae, and of the ischium from the pubis and ilium, may be seen. The limits of the 

 bodies of the 20 sacral vertebrae are also distinguishable. The symphysis of the pubis is 

 cartilaginous. 



Hunterian. 



1367. The bones of the wing of a young Ostrich (Struthio Camelus). 



The antibrachium is one-third the length of the humerus : the carpus presents two bones, 

 placed between the metacarpus and antibrachium. The metacarpus consists of three bones : 



