66 THE ASTEROLEPIS, 



THE ASTEROLEPIS, ITS STEUCTURE, BULK, 

 AND ASPECT. 



With the reader, if he has accompanied me thus far, I shall 

 now pass on to the consideration of the remains of the AsterO' 

 lepis. Our preliminary acquaintance with the cerebral pecu- 

 liarities of a few of its less gigantic contemporaries will be 

 found of use in enabling us to determine regarding a class of 

 somewhat resembling peculiarities which characterized this 

 hugest ganoid of the [Middle] Old Red Sandstone. 



The head of the Asterolepis, like the heads of all the other 

 Celacanth, and of all the Dipterians, was covered with osse- 

 ous plates, — its body with osseous scales ; and, as I have 

 already had occasion to mention, it is from the star-like 

 tubercles by which the cerebral plates were fretted that M. 

 Eichwald bestowed on the creature its generic name. Agas- 

 siz has even erected species on certain varieties in the pattern 

 of the stars, as exhibited on detached fragments ; but I am 

 far from being satisfied that we are to seek in their peculi- 

 arities of style the characters by which the several species 

 were distinguished. The stellar form of the tubercle seems 

 to have been its normal or most perfect form, as it was also, 

 with certain modifications, that of the tubercle of the Coc- 

 costeus and Pterichthys ; but its development as a complete 

 star was comparatively rare : in most cases the tubercles ex- 

 isted without the rays, — frequently in the insulated pap-like 



