456 



Pro£ T. Jeffery Parker. 



[Apr. 17, 



not as a plate-like ingrowth ; its cavity contains a prolongation of the 

 antrum of Highmore. 



There are paired, rod-like Jacobson's cartilages, lying one on each 

 side of the rostrum in the vomerine region. 



In late embryonic life, and even in the adulfc, the quadrate articu- 

 lates with the roof of the tympanic cavity by a double articular 

 surface. 



The hyoidean portion of the tongue-bone chondrifies late — subse- 

 quently to stage G — and never ossifies. 



The Vertebral Column. — As in other Birds, -the atlas arises from a 

 post-occipital intercentrnm and a pair of neurochondrites. The axis 

 consists originally of seven pieces. In both vertebras each of these 

 elements ossifies separately. 



The way in which the notochord is constricted by the ingrowing 

 centrochondrites differs greatly in the various regions. 



The atlas and axis in a newly-hatched embryo differ far less than 

 in the adult from those of the other Ratitse. 



Two intercentra are described in the caudal region. 



A new method of writing the vertebral formula of birds is 

 adopted. 



The Sternum and Ribs* — The development of these parts seems to 

 show that the costal sternum does not originate by the union of all 

 four sternal ribs, but that it extends backwards independently of the 

 third and fourth ribs, meeting them in turn and becoming united with 

 them by joints. 



In some adult specimens the sternum bears a low, median ridge y 

 probably to be looked upon as a vestigial keel. 



The form of the adult sternum is very variable. 



The Shoulder Girdle. — Up to stage H the shoulder girdle is a single 

 cartilage ; during that stage the procoracoid and coracoid are differ- 

 entiated by fenestration. The procoracoid degenerates into a liga- 

 ment, which is sometimes present in the adult. The coracoid fenestra 

 may persist or may be filled up by a preaxial extension of the 

 coracoid. 



Acromial, procoracoid, and acrocoracoid tuberosities are present. 



The coraco- scapular angle varies from 150° to 122°. In stage E 

 the scapula is curved backwards over the ribs. In the same stage 

 the coraco- vertebral angle is 35° ; by stage H it has increased 

 to 90°. 



The adult shoulder girdle is subject to great variation, both in 

 form and size. 



The Fore-limb. — In the carpus a radiale, an ulnare, and the three 



* It is mentioned by the author that uncinate processes (or " uncinates ") are- 

 present in the ribs of Dlnornis, some points in the structure of the foot of which 

 bird are also described. 



