THE CRANIAL SKELETON. 



117 



have a different function from that they have in man ; or 

 having the same function as in him, they may be considerably 

 increased in size and importance. 



They may be absent as distinct bones even in man's class 

 especially in forms which pass a large part or the whole of 

 their lives in water, and where the secretion of tears is super- 

 fluous. 



Thus they are absent by anchylosis with the malar in the 

 Dolphins, and are wanting altogether, unless early anchylosed 

 with the maxillary or malar, in the Seals and Pangolins. 

 On the contrary, though very small, they are present in the 

 Elephant and Sirenia, but in an imperforate condition. 



JflX- 



FIG. 108. UPPER VIEW OF THE SKULL OF A DOLPHIN {Delphinns globiceps). 

 (After Cuvier.) 



c, occipital condyles ; e, median ethmoid in nasal fossa ; f, frontal overlapped by 

 mx, maxilla ; , nasal ; /, parietal, driven down quite to the side of the skull; 

 fi, pre-maxilla (here enormous) ; so, supra-occipital. 



They are present and of good size in many Fishes (e.g. Pris* 

 tipoina\ where each lachrymal constitutes the first of a chain 

 of suborbital scalelike bones, which extend beneath the orbit 

 from before backwards. In Fishes, of course, there is no 

 lachrymal foramen. 



These bones appear to be absent altogether in Batrachians, 

 and sometimes in Birds, though present, and sometimes large, 

 in Reptiles (e.g. Chelonians). 



In that the lachrymal is confined to the orbit, man differs 

 -from most of his own class, except the Apes ; even in animals 

 so high up in the scale as Lemurs it not only extends on to 

 the cheek, but the lachrymal foramen is placed there. 



