54 THE FROG chap, hi 



which has been kept from the first in spirit or formaline : the latter is 

 the more instructive. An additional skull should be carefully cleaned, 

 and then boiled until the numerous bones become separated from one 

 another or disarticulated. 



After observing the form and relations of different parts of the 

 skeleton as described on pp 35 and 36 (Fig. 8, A), they may be sepa- 

 rated from one another for moie detailed examination. The individual 

 vertebrjE should be strung on a piece of wire or string so as to prevent 

 their being lost or misplaced. 



With the specimen before you, work through the characters of the 

 axial skeleton (pp. 36 — 46) : if you omit ihe details given in small type 

 (pp. 40 — 44) at the present stage, do not forget to examine them 

 subsequently. Make sketches of — a. Any one of the vertebrze from 

 the first to the seventh, from the side and from the front and back:; 

 b. the first vertebra; i. the urostyle ; d. the skull from above and 

 from below ; and e. the hyoid. 



It requires considerable skill to make a satisfactory preparation of the 

 chondrocranium, but if you wish to attempt it, procure a large skull 

 which has not been dried, and boil it in water. Carefully separate, by 

 means of a scalpel, most of the membrane-bones (p. 43) ; the palatines, 

 pterygoids, and quadratojugals, and the dentaries and angulosplenials 

 cannot well be disarticulated without destroying the soft cartilaginous 

 parts beneath them. 



Make out — i. The brain-case and \Xs fontanelles and nerve apertures. 

 2. The olfactory capsules. 3. The auditory capsules. 4. The palato- 

 quadrate bar (to which the palatine, pterygoid, and quadratojugal bones 

 have been left attached). 5. The mandibular or Meckets cartilage 

 (to which the angulosplenial and dentary have been left attached). 

 6. The cartilage-bones (exoccipitals, pro-otics, sphenethmoid, and mento- 

 meckelians). 7. The columella, stapes, and fenestra ovalis. Sketch 

 from above and from below. 



Now proceed to examine the appendicular skeleton (pp. 46—52), 

 and sketch the shoulder-girdle and fore-limb, and the hip-girdle and 

 hind-limb. 



SpUt one of the longer hmb-bones (e.g., humerus or femur) 

 longitudinally with a knife, and note the marrow-cavity in the shaft 

 (Fig- 13)- Place another of the long bones in 10 per cent, hydro- 

 chloric acid for an hour or two ; wash thoroughly in water and 

 examine. 



