444 



inner concave from the outer sloping surface of this part of the maxillary. The malar bone 

 is a moderately long and slender piece, bent upon itself at an acute angle, like the scapulo- 

 coracoid in Birds. The upper portion, wedged between the maxillary and frontal, is the 

 thickest : the lower and more slender brauch is bent downwards and backwards, circum- 

 scribing the orbit anteriorly and below, and continued by ligament or fibro-cartilage to the 

 short obtuse zygomatic process of the temporal. There are no lacrymal bones. The ante- 

 rior two-thirds of the middle and under surface of the maxillary is traversed by a vascular 

 and dental groove : rudiments of teeth hidden and buried in the gum are usually found in 

 this groove. The squamosal is a comparatively small, but strong and thick triangular bone : 

 the upper angle represents the expanded squamous part in land mammals, and is articulated 

 by broad dentated sutural margins to the frontal and exoccipital : its anterior border is 

 grooved for the reception of the alisphenoid : the lower angle is, as it were, truncated, and 

 presents a rough surface for the attachment of the petrotympanic : a short obtuse anterior 

 angle bends forwards and represents the zygomatic bone : the under surface presents a smooth 

 shallow cavity for the condyle of the lower jaw ; the inner border of the glenoid surface being 

 produced downwards into a slender styliform process. The condyle of the mandible projects 

 from the posterior part of the base or ascending ramus, which is compressed and produced 

 into a low obtuse coronoid process above, and into a similar angle below : a wide excavation be- 

 ginning, on the inner side of the ascending ramus, deepens and contracts into the dental canal, 

 which enters the substance of the horizontal ramus : a fissure is continued along the inner 

 side of the ramus from this canal, and is the sole indication of a compound structure of the 

 jaw. The vessels and nerves emerge from several foramina at the outer side of the ramus, 

 where it is attached by its long symphysis to its fellow : the upper border of the symphysial 

 part of the ramus is excavated by a continuous dental canal or groove, now somewhat resem- 

 bling that in the upper jaw. The length of the symphysis in the present skull of the foetal 

 Cachalot is three-fourths that of the rest of the ramus. In the adult male the dispropor- 

 tionate growth of this part of the jaw leads to an excess of length of the symphysial part 

 beyond the rest of the ramus. 



Purchased. 



2448. The two rami of the lower jaw, wanting the teeth, of a Cachalot (PJiyseter 

 macrocephalus) . Hun terian . 



2449. The rami of the lower jaw, with the teeth, of a male Cachalot (Physeter ma- 

 crocephalus). 



The symphysis of the jaw is coextensive with the dental series, which consists, in each 

 ramus, of twenty-seven teeth, conical or ovoid, according to their state of development and 

 usage : the smallest teeth are at the two extremes of the series. In the young Cachalot they 

 are conical and pointed, but become obtuse by use, whilst progressive growth expands aud 

 elongates the base into a fang, which then contracts, and is finally solidified and terminated 

 obtusely. The teeth are separated by intervals as broad as themselves. In respect to their 

 mode of implantation they offer a condition intermediate between that of the teeth of the 



