318 NOTES ON THE STRUCTURE AND RELATIONS 



we find the large teeth standing close together in groupes of 

 twos and threes on the one side of the jaw, while the corre- 

 sponding teeth on the other side of the same jaw stand apart. 

 This general irregularity is shared in some cases by those 

 terminal teeth of the under jaw which are received by the 

 perforations in the intermaxillaries ; and in a specimen of 

 Lepidosteus on the table before us, we find in the left inter- 

 maxillary two little holes beside each other, formed to re- 

 ceive two teeth, that stand a little apart, and in the right 

 intermaxillary the two little holes represented by one large 

 hole, formed to receive three teeth, which stand close to- 

 gether. 



Now, in the jaws of the Palaeozoic Coelacanths, those huge 

 reptile teeth which stand up over and behind the ichthyic 

 ones were received, as in the alligators and the Lepidosteus, 

 into cavities hollowed in the opposite jaws ; but though in 

 some of these ancient fishes, especially the Holoptychii 

 (Rhizodus) of the Carboniferous rocks, the reptile teeth of 

 the lower jaw nearest to the symphysis were greatly larger 

 than the others, and must have had cavities of greater depth 

 in the upper jaw hollowed to receive them, the arrangement 

 was not restricted to these anterior teeth, but pervaded both 

 jaws, under and upper, along their entire length, from the 

 snout to the angles of the mouth. In most of my specimens 

 of jaws of Ccelacanths from the Lower Old Ked Sandstone, — 

 in especial, in those of the Asterolepis, — each of the reptile 

 teeth, from near the condyloid processes to the symphysis, 

 stands out of the one side of what seems to be a socket 

 twice too wide for it, — in other words, beside each reptile 

 tooth there is a pit which received the reptile tooth in the 

 opposite jaw when the mouth was closed. [Spec. L] 

 Generally as they approached the sides of the mouth, the 

 pits were smaller than towards the snout ; but they are as 

 decidedly there, save in the cases in which some irregula- 



