INDEX 



Abdominal pores, 271. 



Acanthias, larva of, 21 6 (Figs. 288, 

 289). 



Acanthodes, gill shields, 20; a fossil 

 shark of the Coal Measures, 79; 

 structure of, 80, 8i; A. wardii, 81 

 (Fig. 87) ; shagreen and denticle of 

 A. gracilis, 8 1 (Fig. 88); affinities 

 of, 95; diagram of affinities, 98 

 (Fig. 103) ; gill arches, 1 14. 



Acanthodians, antiquity of, 9; fin 

 spine and pectoral fin, 28, 29 (Fig. 

 32); pectoral fin of Parexus, 42 

 (Fig. 51), 44. 



Acanthodopsis wardii, teeth of, 82 

 (Fig. 88 A}. 



Acanthopterygian, 166 (Fig. 171 A). 



ACANTHOPTERYGII, in classification, 9 ; 

 as a subdivision of Teleocephali, 174. 



Acipenser, in classification, 8; antiquity 

 of, 9, 1 66 (Fig. 171 A}; swim-blad- 

 der of, 22 (Fig. 1 3) ; description of, 

 159-161; A. sturio, 160 (Fig. 165); 

 eggs and breeding habits, 181 (Fig. 

 194), 185; fertilization, 187; devel- 

 opment of eggs, 203 (Figs. 249- 

 264), 207; larval development of, 

 221-223 (Figs. 296-302); heart, 

 oonus and bulbus arteriosus, tables, 

 260; gills, spiracle, gill rakers and 

 opercula, tables, 261 ; digestive tract, 

 tables, 262 (Figs. 326-331); swim- 

 bladder, tables, 264, 265 (Fig. 13); 

 genital system, tables, 266; urino- 

 genital ducts and external openings, 

 tables, 267 (Figs. 332-337) ; excre- 

 tory system and urinogenital ducts, 

 tables, 271. 



ACTINOPTERYGII, in classification, 8, 

 147; description of, 155-178 (Figs. 

 157-185 A)\ Chondrosteans (Gan- 

 oids), 155; fossil forms, 155-159 

 (Figs. 158-164); living types, 159- 

 178 (Figs. 165-185 A}. 



Actinotrichia, 31, 33 (Fig. 39). 



dZtheolepis, ganoid plates of, 24 (Fig. 



25), 25. 



Agassiz, L., 37, 66, 107, ill. 

 Agassiz, A., 224. 

 Air-bladder, v. Swim-bladder. 

 Allis, E. P., 50, 51. 

 Alopias,%<); A.vulpes (thrasher shark), 



89 (Fig. 95). 

 Alosa, eggs and breeding habits, 181 



(Fig. I97)> 186. 



American Arthrodirans, 130. 



American Geologist, 80. 



Amia, in classification, 8; antiquity 

 of, 9, 1 66 (Fig. 171 A); swim-blad- 

 der of, 21, 22 (Fig. 14) ; sensory 

 tracts in head dermal plates, and 

 scales of, 50-52 (Figs. 64-68) ; A. 

 calva, 51 note; a Ganoid with her- 

 ring-like scales, 145 ; description of, 

 163-165 (Figs. 167, 168); Mesozoic 

 forms, 164, 165 (Figs. 169-171); 

 heart, conus and bulbus arteriosus, 

 tables, 260; gills, spiracle, gill rakers, 

 and opercula, tables, 261 ; digestive 

 tract, tables, 263; swim-bladder, 

 tables, 264, 265 (Fig. 14); genital 

 system, tables, 266; excretory sys- 

 tem and urinogenital ducts, tables, 

 271. 



Amiurus, barbels of, 46, 47 (Fig. 58). 



Ammoccetes, head of, 61 (Fig. 72 C"), 



285 



