518 EDWIN S. GOODRICH. 



Tig. 4. — Tluee endo-skelelal fin-supports and some dermal fin-rays of tlie 

 second dorsal fin of Scaumenacia curta. The distal end of the lowest 

 endo-skeletal ray lias been exposed by the removal of the covering dermal 

 rays. Slightly diagrammatic and enlarged. 



Fig. 5. — Enlarged and somewhat diagrammatic view of the anterior region 

 of the large dorsal lobe of the caudal fin of Eusthenopteron Foordi, 

 showing the relation of the dermal rays to the body-scales and endo-skeletal 

 fin-supports. 



Fig. 6. — Enlarged view of a small part of a dermal ray of the same 

 Eusthenopteron. 



PLATE 3G. 



Fig. 7. — Small portion of a transverse section through the ventral lobe of 

 the caudal fin of an embryo Scyllinm canicula, 80 mm. long, showing tlie 

 ceratotricliia, the connective-tissue layers, and the developing denticles. 

 Cam. X 300. 



Fig. S.— Section through the skin of the caudal fin of an embryo Scylliu m 

 canicula, 23 mm. long, cutting a little obliquely through the developing 

 ceratotricliia. Cam. oil im., oc. 8. 



JfiG, 9, — Section through the ventral lobe of the caudal fin of an enibiyo 

 Scyllium canicula, 80 mm. long, cutting the ceratotrichia longitudinally. 

 Cam. X 450. 



Fig. 10. — Similar section nearer the edge of the fin, and cutting the 

 ceratotrichia across. Cam. X 300. 



Fig. 11. — Section of the ventral lobe of the caudal fin of an embryo 

 Scyllium canicula, 60 mm. long, cutting across the ceratotrichia. Cam. 

 X 300. 



Fig. 12. — Similar section of the fin of an embryo Scyllium canicula, 

 23 mm. long. Cam. x 300. 



Figs. 13 — 15. — Sections through the same dorsal fin of a young Proto- 

 pterus, cutting across the dermal rays. The section represented in Fig. 13 is 

 nearest the edge, and that in Fig. 15 nearest the base of ihe fin. Cam. 

 X 300. 



Fig. 1G. — Similar section through the same fin near its base, showing the 

 developing scales. Cam. X 300. 



PLATE 37. 



Fig. 17.— Section through the distal region of the pelvic fin of Poly pterus 

 lajjradii, showing the actinotrichia, and the lepidotrichia developing as a 

 thickening of the basement membrane. Cam. X 350. 



