THl!] DEEMAL FIN-RAYS OF FISHES. 510 



Fig. is. — Section nearer the base of the same fiii. The lepidotricliia are 

 lieie thick, bony, and armed willi denticles. X 80. 



Fig. 19. — Section through the distal region of the pectoral fin of Lepi- 

 dostens osseus, showing the actinotrichia and the young lepidotrichia cut 

 across. Cam. x 350. 



Pigs. 20 — 23. — Sections through the caudal fin of a young trout, Salnio 

 fario, 21 mm. long. The sections pass progressively nearer the base of the 

 fin, Fig. 20 representing that nearest the edge. The developing lepidotricliia 

 are cut tiirough transversely. Cam. X 700. 



Fig. 24. — Approximately longitudinal section through the developing 

 actinotrichia and lepidotrichia, taken from the caudal fin of a young Sal mo 

 fario, 45 mm. long. Cam. X 700. 



Fig. 25. — Transverse section through the proximal region of the caudal fin 

 of a young Salmo fario, 21 mm. long. Cam. X 45. 



Fig. 26. — Transverse section through the base of the anterior dorsal fin of 

 the same fish. 



PLATE 38. 



Fig. 27. — A few of tlte dermal rays and superficial scales of tiie pelvic fin 

 ofDipterus valenciennesi (No. P. 618 of the British Museum). En- 

 larged. 



Fig. 28. — Still more enlarged view of a small portion of the same. 



Fig. 29. — Enlarged view of small portions of the dermal rays of the 

 pelvic fin of C e r a 1 d u s F o r s t e r i. 



Fig. 30. — Transverse section through the ventral iobe of the caudal fin of a 

 young Protopterus. Cam. X 40. 



Fig. 31. — Longitudinal section through the dermal ray of the same 

 Protopterus, showing the inner and outer layers. Cam. X 400. 



Fig. 32. — Transverse section through the proximal tinjointed region of tlie 

 dernuil rays of the anal fin of Dipterus valenciennesi. Cam. X 110. 



Fig. 33a. — Transverse section through the proximal unjoiuted region of 

 the dermal rays of the ventral lobe of the caudal fin of Scaumenacia 

 curt a. Cam. x SO. 



Fig. 33b. — Section of the distal segmented region of the same. Cam. 

 X 80. 



Pig. 34. — Transverse section through the distal jointed region of the 

 dermal rays of the pectoral fin of Ceratodus Forsteri. Cam. x SO. 



Fig. 35.4. — Enlarged view of two dermal rays from the anal fin of 

 Dipterus macropterus. 



