[73] THE OSTEOLOGY OF AMIA CALVA. 819 



the anterior extremity of the arch to which it belongs. The nietaptery- 

 goid (Fig. 32, M, Ft.), a flattened and irregularly shaped bone is wedged 

 in between the hyomandibular and quadrate, and firmly establishes 

 the connection of the two arches at this extremity. It overlies also a 

 thin scale-like process thrown out on the part of the ectoptery-goid, just 

 opposite the angle this bone makes above its articulation with the 

 quadrate. The ectopterygoid is a bent and narrow strip of bone that 

 directly connects the quadrate with the palatine. It forms the outer 

 margin of the floor of the orbit, which is chiefly made up of the ento- 

 pterygoid. Both the palatine and ectopterygoid support a dense area 

 of very fine teeth upon their lower surfaces. The entopterygoid is a 

 beautiful shell-like bone which is overlapped by the palatine anteriorly 

 and the metapterygoid behind. It is bent upon itself at about its lower 

 third towards the median plane, and thus forms the greater part of the 

 floor of the orbit by its upper surface, and by its lower the roof of the 

 mouth. The entopterygoid is quite transparent, and for some little 

 distance from its outer margin marked by wavy and delicate concen- 

 tric lines. 



Although the bones just described are so intimately connected with 

 the quadrate, I prefer to call this arch, as I have done above, the 

 pterygopalatine, considering the quadrate as the property of the sus- 

 pensorium. It is often termed, however, the palato quadrate arch, and 

 I took occasion to use this term in the first part of this paper. 



Oftlie Hyoid and Branchial Arches ofMicropterus. — Our large-mouthed 

 black bass offers us very little that differs from the more typical Teleos- 

 teans in the skeletal parts of its respiratory apparatus. From the lower 

 end of each hyomandibular there is, as we saw above, suspended a small 

 rod of bone, the interhyal (the stylohyal of many authors). To these is 

 articulated, on either side, a broad triangular piece, the epihyal (Fig. 

 32, E. hy.), which in its turn connects with the larger and longer i)iece, 

 the ceratohyal. The connection between these two latter elements is 

 very much strengthened by a longitudinal lashing of bony fibers on the 

 inner aspects over the joint, the bones themselves being quite com- 

 pressed and flattened i)lates of a form shown in the figure. The cerato- 

 hyals, the anterior pair, meet in front in a ligamentous symphysis, over 

 which ride, side by side, two other separate elements, the hypohyals {H. 

 hy.). These are broadly conical in form, with their apices drawn out 

 into blunt processes, which are directed upwards and backwards. Best- 

 ing upon the hypohyals above is an azygos bone about a centimeter 

 long (in a bass that would weigh three pounds), which is the glosso- 

 hyal (Fig. 27, G. hy.). It is a flattened bone, shaped somewhat like 

 the vertical section of an hour-glass, it being the part of the skeleton 

 which supports the soft parts of the tongue. This bone has also been 

 called the os Unguale. It may be absent in some of the true bony fishes. 



In the specimen I have in my hand we see on the outer aspect of the 

 epihyal, just above its lower and near its anterior border, two large and 



