98 ORGANS OF SUPPORT, 



find here two lengthened slender pelvic bones, unconnected 

 with the rest of the skeleton, and having the rib-like form of 

 the iliac bones of fishes and amphibia. 



The head is most lengthened, straight, and fish-like in the 

 piscivorous cetacea, as the porpoise (Fig. 53,) where the 

 face is chiefly composed of the long maxillary and inter- 

 maxillary bones, (,) and the vomer, which is extended 

 between them. The small nasal bones are placed far back- 

 wards upon the forehead, behind the nasal apertures, and 

 behind them is the narrow band of the frontal bone, which 

 is in contact with the occipital, from the parietals being 

 confined to the temporal region of the head. From the 

 great extent and the vertical position of the occipital bone, 

 and the extension of the maxillary bones upon the forehead, 

 the cranium is here generally small, compared with the face, 

 and is much extended transversely ; great extent of surface 

 for muscular attachment is thus given to the back part of the 

 head, and great development to the jaws in front, for pre- 

 hension. The teeth, like those of fishes and reptiles, are 

 adapted for prehension, and not for mastication ; they are 

 similar in form, conical, bent, and placed alternately in the 

 opposite jaws. In the cachalots, they are present only in 

 the lower jaws, which are very narrow, and in contact with 

 each other throughout the greater part of their course, and 

 thus are opposed only to the middle part of the roof of the 

 mouth. In the foetus of the balsena there are teeth in the 

 lower jaws, which soon entirely disappear, and the alveolar 

 margin of the upper jaws are occupied with vertical, long, 

 thin, horny laminae, which are fimbriated on their inner 

 edges, and by straining the water, they collect the small 

 floating animals on which the whales feed. The malar bone 

 forms the lower boundary of their very small orbit (f,) and 

 is here a remarkably thin, slender, and curved bone, com- 

 pared with the massive malar bone of the herbivorous spe- 

 cies, which require a more powerful masseter for mastication. 

 The petrous and tympanic portions of the temporal bone, 

 though anchylosed together, are connected only by cartilage 

 to the other bones of the skull, the ethmoid bone presents 

 no cribriform plate, and the infraorbitary foramen is divided 

 into a series of small apertures extending forwards along the 

 upper jaw-bones. The right side of the head is generally 



