310 J K. Thacher — Median and Paired Fins. 



Plate LVII. 

 Figures 49, 50 — Eugomphodus litoralis. Anal. 

 Figures 51-54. — Squalus (Acanthias) Americcmus. First dorsal. 



Figures 55, 56. — " " " Second dorsal. The spine is re- 



moved in figs. 53, 55, 57 ; but not in ligs. 51, 52, 54, 56. 



Plate LVIII. 



Figure 57. — Squalus Americanus. Second dorsal. 



Figure 58. — Baia levis. First dorsal. 



Figure 59. — " " Second dorsal. 



Figure 60. — Myliohatis Fremenvillei. Sole dorsal. 



Figure 61. — Acipenser brevirostris. Sole dorsal; a, neural arch; 6, intercalary carti- 

 lages ; c, neural spine ; d, foramen for ventral branch of spinal nerve ; e, foramen 

 for dorsal branch of spinal nerve. 



Plate LIX. 



Figure 62. — Acipenser brevirostris. Anal. Opposite 2-| vertebrae. 



Figure 63. — Section of vertebrarium of Acipenser brevirostris; a, neural spine; 6, 



ligamentum longitudinale ; c, neural arch. 

 Figure 64. — Acipenser brevirostris, left ventral, from above ; a, iliac process. 

 Figure 65. — Acipenser brevirostris, portion of right ventral, from below. 

 Figure 66. — Section of pectoral fin of Mustelus canis. 

 Figure 67. — Mustelus canis, ventral. 

 Figure 68. — Mustelus canis, pectoral detached from girdle. 



Plate LX. 



Figure 69. — Eugomphodus litoralis. Ventrals; a, b and c nerve-foramens. 



Figure 70. — Pectoral limb of Ichthyosaurus, after Cuvier. Car., carpalia ; Cen., 



centralia ; u, ulnare ; i, intermediiun ; r, radiale ; U, ulna ; R, radius ; II, humerus. 



I take, though with some hesitation, Gegenbaur's indentification of the radial and 

 ulnar sides in this limb of IcMhyosaurv,s. 

 Figure 71. — Gryptobranchus Japonicu^s. Hind foot, after Hyrtl, Schediasma anatomicum, 



1865. 



