212 ELEMENTARY BIOLOGY. [XIII. 



7. The posterior cornua, or ihyro-hyals ; bony, and 

 shorter and thicker than the anterior cornua : 

 attached to the posterior border of the body 

 near the middle line and diverging as they run 

 backwards. 



&. Two pairs of smaller processes formed by the 

 elongation of the anterior and posterior angles 

 of the body of the hyoid. 



e. The sternum and shoulder-girdle. 



1. Their general arrangement : they form an incomplete 

 ring round the fore-part of the trunk : this ring is 

 composed partly of bone, partly of cartilage. Note 

 the hollow {glenoid fossa) with which the fore-limb 

 articulates. 



a. The sternum : situate in the ventral median line 

 and made up of several parts : beginning behind 

 we find — 



a. The xiphisternwrn; a thin cartilage, wide behind, 

 narrow in front, where it passes into — 



/3. A median cartilage ensheathed in bone, the 

 sternum proper. The anterior end of the ster- 

 num unites with the posterior and internal 

 angles of the coracoids (&. 7), the inner edges 

 of which meeting in the middle line separate 

 the sternum from — 



7.. The omosternxim, consisting of a slender, flat- 

 tened bone, terminated in front by an expanded 

 cartilage. The posterior end articulates with 

 the praecoracoids and the clavicles. 



h. The shoulder-girdle: beginning dorsally, it ex- 

 hibits on each side — 



