68 ELEMENTARY BIOLOGY. [CHAP. 



c. Its anterior cornua, slender cartilaginous rods, 

 arising from the front of the body on either side : 

 each is long and curved, running at first forwards, 

 then backwards and outwards, and finally for- 

 wards and upwards, to become attached to the 

 periotic capsule below the fenestra ovalis. 



7. The limbs and limb-girdles. 



These are best studied in the wet state. In 

 dealing with the carpus and tarsus, no difficulty will 

 be found if treated as follows. Isolate sufficient of 

 the limb-skeleton to embrace the carpus or tarsus 

 and pick away any fragments of the soft parts which 

 may remain; immerse in spirit for a few hours; 

 transfer to absolute alcohol for 1 hour, thence into 

 oil of cloves. The latter medium will thoroughly 

 clarify the preparation, and it may be kept in it for 

 an indefinite period. 



The shoulder-girdle and its related structures. 



a. Their general arrangement : they form an incom- 

 plete ring round the fore part of the trunk, com- 

 posed partly of bone, partly of cartilage. Note 

 the cavity (glenoid fossa) with which the fore-limb 

 articulates. 



Examine from the ventral aspect ; the whole is 

 seen to consist of 



a. Paired elements ; symmetrical on opposite sides 

 and meeting each other in the mid-ventral 

 line. 



/?. Median elements; in corresponding relationship 

 anteriorly and posteriorly with the applied ven- 

 tral ends of a. 



