[81] THE OSTEOLOGY OF AMIA CALVA, 827 



works of Agassiz, Cuvier, Coi^e, DeKay, Gill, Giinther, Hnxley, Jordan, 

 Miiller, Owen, Eolleston, or Yogt." 



With regard to their location and general appearance, this author 

 states that " in the adult Amia there are two appendages on each side. 

 They are usnallj^ concealed from view by the operculum ; but the tip cf 

 the hinder one sometimes projects beyond the operculum at a point a 

 little above the base of the pectoral fin. The anterior appendage is 

 about 2 centimeters long, and its anterior extremity is a little more than, 

 half its length from the union of the isthmus with the hyoid arch. Its 

 hinder end is nearly opposite the medium tip of the shoulder-girdle. It 

 is wholly sui)erficial, and its hinder border i)rojects but slightly beyond 

 its attachment. The i)osterior appendage is about twice the length of 

 the anterior, and consists of three portions : a short triangular root just 

 beneath the skin ; a short but broad base, the deep surface of which is 

 continuous with the skin; a long free portion, whicli gradually tapers 

 backward to the tip, which is less than l'"'" wide. The root lies to the 

 mesial side of the posterior extremity of the anterior appendage, but 

 there is a distance of nearly 2™°^ between them. The posterior append- 

 age inclines dorsad, and rests quite closely against the adjacent surface 

 of the shoulder-girdle. 



"jSTeither has any direct connection with bone. The attached sur- 

 faces rest upon the muscles which constitute the isthmus, but do not 

 appear to be attached to them. While observing living Amias with ref- 

 erence to their respiratory function I never saw any movement of these 

 appendages. The thickness of the posterior one is about ^ ™"\ It is 

 quite flexible during life and while moist, but becomes more rigid when 

 dried. 



" The free surfaces of both appendages are corrugated in the adult. 

 The general direction of the ridges and furrows is across the length of 

 the surfaces obliquely forward from the dorsal toward the ventral bor- 

 der. The ridges are more or less wavy in outline, and present irregu- 

 larities of direction and arrangement, especially toward the tip and 

 ventral border of the posterior appendage. But the distance between 

 any two ridges is quite uniform; the number of ridges being about 18 

 to the centimeter u^jon the anterior appendage, and about 12 upon the 

 posterior. The transverse ridges do not always reach the ventral bor- 

 der upon the anterior two-thirds of the posterior appendage ; the ventral 

 third of the surfaces is in some cases nearly free, but may present one 

 or more ridges running nearly parallel with the border, or more often, 

 especially on the inner surface, there may be a series of short ridges 

 trending dorsad and forward from the lower border to meet the dorsal 

 series at open angles. 



" The anterior slopes of the ridges form an angle of about 45° with 

 the surface; but the posterior slopes are nearly perpendicular. The 

 crests are projected backward as numerous fine teeth which are barely 

 visible to the naked eye." 



