398 D^ VISON. [Vol. XI. 



termination of the liver. The most important information was 

 gained from the study of the heads of several specimens stained 

 in toto in borax-carmine and cut serially into sections one-fif- 

 tieth of a millimetre in thickness. Horizontal as well as sagit- 

 tal and transverse sections were made. 



TJie Skeletal Anatomy of the Head. 



The skeleton of the head is shorter and broader than in the 

 adult. The ossifications are, of course, vastly different. There 

 are but sixteen fully ossified elements in the cranium: pre- 

 maxillary, nasals, frontals, prefrontals, parietals, squamosals, 

 maxillaries, vomero-palatines, and parasphenoid. The follow- 

 ing elements are partially ossified: orbitosphenoids, prootics, 

 and exoccipitals. The pterygoids, quadrate and stapes are 

 wholly cartilaginous. The premaxillary is quite the same as 

 in the adult, and needs no further description than to state 

 that the interosseus septum is not derived from the nasal roof- 

 ing cartilage, as Wiedersheim (i) has suggested. The two 

 elements, though in contact, present no transition from one to 

 the other. The enveloping cartilage of the nasal sac is incom- 

 plete where the osseous septum is present. The union of the 

 cartilaginous floors of the nasal sacs medially extends beneath 

 the anterior part of the brain for a short distance, when the 

 middle portion of the cartilage passes into connective tissue, 

 leaving two lateral bars. Hay (3) speaks of an unpaired piece 

 of cartilage lying in the roof of the mouth of the adult be- 

 tween the anterior ends of the vomero-palatines, and states that 

 it is not found in his embryos. Wiedersheim speaks concern- 

 ing the same as follows : " Da wo die Vorderenden der Vofnero 

 palatine in der Mittellinie zusammenstossen, ragt ein conisch 

 gestalteter Knorpelzapfen vom Boden der Nasenhohle in die 

 Schleimhaut des Mundes herab, von welcher er einen Ueber- 

 zug erhalt." 



Hay believes that this nodule of cartilage has been cut off 

 from that forming the floor of the nasal sacs by the union of 

 the bones in the roof of the mouth. Fortunately my specimen 

 is of just the proper stage to settle the question. The roofing 



