[71] THE OSTEOLOGY OF AMIA CALVA. 817 



As in so many other bony fishes, we find in this Bass a series of ir- 

 regularly-shaped bouelets, circumscribing the lower boundary of the 

 orbit. These are the suborbitals (Fig. 27, 8b. o.). They are seven or 

 eight in number, the hinder one resting on the postfrontal, while the 

 large anterior one, which, in common with other osteologists, I have 

 termed the lacrymal, overlaps, when in position, the maxillary and j)re- 

 frontal {La.). On either side of the ethmoid, and what at first appears 

 to be almost a continuation of this chain of bones, we observe another 

 slender osseous element. This is the nasal. A mucus canal perfo- 

 rates its substance for its entire length (Fig. 27, JSFa.). In designating 

 these bones as the nasals, I am aware it disagrees with what Sir Rich- 

 ard Owen has, stated in his Anatomy of Vertebrates in the matter (Vol. 

 I, pages 113 and 114), and must believe with Parker that " the proper 

 nasal {na.) is a small ossification on each nasal roof, external to the 

 supraethmoid in its middle region " (The Salmon, Morph. of the Skull, 

 page 74). I must also believe, until some better observer corrects me, 

 that the bone I have described as the ethmoid in Megalops and Albula 

 is a single ossification in the adult, and the nasals of these forms I take 

 to be missing in the specimens in hand. Resting on the forward end 

 of the cranium in Micropterus we find a handsomely developed pair of 

 premaxillaries (Fig. 27, Fmx.). Each bone has an ascending process in 

 this region of its support, and when the two are properly articulated 

 they form a graceful and nearly semicircular arch, the lower surface 

 of which is thickly studded with very fine teeth. A rounded, lamelli- 

 form i)rocess is also developed on the upper side of the limb of each 

 premaxillary, about one-third the distance above its pointed extremity 

 (Plate YIII, Fig. 22). 



The maxillary is a large bone, with expanded hinder extremity, on 

 the upper border of which it supports an admaxillary (Figs. 27 and 22a). 

 It is completely edentulous as in most other osseous fishes. Ante- 

 riorly it does not meet its fellow of the opposite side, but develops at 

 this end, internally a circular and vertical disk, with a raised facet to 

 articulate with the cranium. Another elliptical disk is found at this 

 extremity, directed outwards. It is for the maxillary process of the 

 palatine to play on. The form of the palatine in Micropterus is well 

 shown in Fig. 22, PI. This bone being firmly articulated with the 

 palato-quadrate arch, and the n^axillaries and premaxillaries being 

 freely movable, the mechanism of these latter bones offers an in- 

 teresting study. The manner in which they may move upon each other 

 is easily seen in Fig. 22. This is still more engaging a subject in 

 those fishes with protractile snouts, of which there are many genera. 



In Micropterus the opercular group of bones is very well developed 

 (Fig. 27, and Plate XIII, Fig. 32, Op., 8. Op., Pr. 0., and J. Op.). The 

 operculum is a beautiful scale-like plate of bone, the largest of the four. 

 In outline it is an irregular quadrilateral, with a reinforced border on 

 its anterior margin, which is so fashioned and strengthened at its upper 

 H. Mis. 67 52 



