[79] THE OSIEOLOGY OF AMIA CALVA. 825 



In Micropterus there are two of these bones, an upper and a lower 

 one, attached to the other elements of the girdle by ligaments. The 

 upper piece is a scale-like bone parallel to the median plane, while the 

 lower segment is a straight spine resting upon the inner aspect of the 

 entire length of its anterior border (Fig. 23 T.}. This lower teleotem- 

 poral was regarded by Garus as a displaced iliac bone. These teleotem- 

 porals of the bass rest against the coracoids, and above the proscapula 

 (Fig. 23). This latter element in Amia presents for examination a ver- 

 tical portion, which has a strong process developed, directed upwards, 

 at its antero-superior angle, a feature it holds in common with Microp- 

 terus. I^ow, the outer aspect of this vertical portion is sculptured in 

 Amia like the opercular bones, while in the bass it is marked like its 

 own opercular bones, with white, wavy lines and radiations. 



The proscapula of Amia next sends off anteriorly from its vertical 

 plate, nearly at right angles, a longer and broader portion. This part 

 is pointed at its further end where it articulates with the fellow of the 

 opposite side by ligament. Its upper surface is gently convex, and its 

 inner margin is fortified by a raised rim, directed downwards. This 

 rim, similarly situated, becomes a ijrominent feature in Micropterus 

 (Fig. 23), and the coracoids articulate at its lower edge. They occupy 

 nearly the same position in Amia, but here they have become com- 

 pletely amalgamated and are represented only in cartilage {Yn.). Mi- 

 cropterus lacks a mesocoracoid, but both the hyper- and hypocoracoid 

 are thoroughly developed. The hypercoracoid is perforated about its 

 middle by an elliptical foramen (Fig. 23, Hyp. c), which is met in many 

 other Teleosteans. Above, this bone articulates with the proscapula, 

 as described above j anteriorly it articulates with the hypocoracoid 

 {Hyo. c), lying in the same plane, while below it articulates with three 

 of the actinosts; the fourth and largest of these bones articulating 

 with the hypocoracoid. This latter bone throws forwards a long, lamel- 

 liform spur that reaches far forwards on the under side of the proscap- 

 ula. It shows a rounded notch behind, just anterior of the facet for 

 the lower actinost. There are four actinosts in Micropterus, shaj^ed like 

 little dice-boxes, and forming a graded series as regards their size. 

 From their hinder ends spring the sixteen rays that go to form the pectoral 

 Jin (Plate XIV, Fig. 35, Ast. Pf.). I find nine actinosts in the carpus of 

 Amia, composed of very elementary bone, with dilated posterior ends, 

 to which are attached the twenty-two rays of the pectoral fin. We 

 cannot see all of these in Fig. 24, because the view does not admit of 

 it, but they are correct in Fig. 35. Delicate markings encircle these 

 rays for their entire length, commencing a short distance beyond their 

 anterior ends. 



These members, after passing backwards for about half their dis- 

 tance, divide in two, the forks keeping close side by side and one above 

 the other. This phenomenon is repeated once more before arriving at 

 the posterior margin of the fin. A similar splitting of the fin rays 



