[45] THE OSTEOLOGY OF AMIA CALVA. 791 



iug', and what differs from Jordan and Gilbert's description, the pecto- 

 ral and ventral fins in these two specimens were of a bright Prussian 

 green. The two remaining specimens were smaller fish, much lighter 

 in color, being sort of a clay-brown, with the fins of a similar shade, 

 and less mottled than the others, with the caudal ocellation present, 

 only not so large or brilliant. 



OF THE GANOID PLATES. 



This series of investing bones of the cranium have been so thoroughly 

 described by Sagemehl above, and by Bridge in the Journal of Anat- 

 omy, that I shall content myself with a running review of them, with 

 special references to the fine specimen before me, from which I made 

 my drawing. (Plate IV, Fig. 16.) 



The most extraordinary thing about Bridge's description is that he 

 seems to have secured a specimen for his dissection, wherein the parie- 

 tal dermo-plates were in one piece, without any trace of a suture be- 

 tween them. To the united bone this anatomist gave the name of the 

 dermo-sui)raoccipital, which is commented upon by Dr. Sagemehl in 

 Part I of this paper. 



It seems hardly possible that Bridge could have been mistaken in this 

 matter, as he made special search for the sutural trace dividing them, 

 aware as he was of Owen's already having mentioned that two plates 

 occupied the site of his dermo-supraocci])ital. Moreover, the sculptur- 

 ing would be different on a single plate, as the rugosities would radiate 

 from a single center to the borders as they do in the other plates. 



In all the specimens that I have examined, including the one before 

 me, these parietal plates, existed as described by Dr. Sagemehl, even to 

 the detail of the suture not terminating in the median line posteriorly 

 as shown in Plate I, Fig. 1, Pa. This was the condition found and de- 

 scribed also by Franque, who gives a very good rei)resentatiou of a 

 superior view of the dermal plates in this fish. (Plate II, Fig. 7.) 



The arrangement in my specimen is precisely the same as in the speci- 

 men drawn by this latter anatomist, the right-hand plate extending 

 more anteriorly and the suture between the bones deflected to this side 

 posteriorly. Figure 7 should show, however, more marked serrations 

 of the margins of the bones anteriorly, as they are invariably found to 

 be so in nature. 



External to the parietal plates on either side we find a longer and nar- 

 rower bone, sculptured as the rest, which is the squamosal. (Plate IV, 

 Fig. 16, Sq.) 



Behind the squamosals and parietals, the hinder margins of which 

 form nearly a straight suture across the skull, we find the supra- 

 temporals, two rather long, triangular plates placed transversely with 

 their blunted apices meeting in the median line (Fig. 16, ^S'. tp.). These 

 two plates shut out from superior view the two forked limbs of the 

 pqsttemporals upon which they rest. 



