NOTES ON Ml'iDIAN AND PAIRED FINS OE FISH. 375 



All the figures refer to Scyllium caiiicula, and the arrows point towards 

 the head. In several of the figures the myotonies, their muscle-buds, and the 

 radial muscles are drawn in red. Blue in fig. 2i represents sensory nerves. 



The spinal nerves in the embryo are numbered from the first ganglion, ia 

 the adult from the first which issues behind the skull. About five myotomes 

 are found in embryos in front of the first ganglion. When portions of the 

 embryos were cut off before imbedding, the number of the ganglia was esti- 

 mated, and an .r inserted before it to denote its uncertainty, as in fig. 4. 



PLATE 10. 



Fig. 1. — llcconstruction from serial longitudinal sections of a portion of an 

 embryo about IS mm. long. It is cut off behind the first dorsal fin. The 

 pectoral fin has been cut off near its base. 



Pig. 2. — Reconstruction of the first and second dorsal fins of an embryo 

 24 mm. long. 



Fig. 3. — Reconstruction of the first dorsal fin of an embryo 26 mm. long. 



Fig. 4. — Reconstruction of the first and second dorsal fins and of a portion 

 of the pelvic fin of an embryo 19 mm. long. 



Pig. 5. — Longitudinal vertical section of the hinder region of the first 

 dorsal fin of an embryo 28 mm. long. The radials are beginning to appear ; 

 the extremities of several muscle-buds are seen above. 'Cam. Ob. Z.,' 

 a a, 00. 3. 



PLATE 11. 



Fig. 6. — Reconstruction of a portion of an embryo 28 mm. long (same as 

 that in fig. 5), with the first dorsal and pelvic fins. 



I'iG. 7. — Reconstruction of the first dorsal fin of an embryo 33 mm. long. 

 Both the muscles and the precartilage radials are represented. 



Pig. S. — Longitudinal horizontal section of the first dorsal fin of an embryo 

 32 mm. long. Z. A. oc 3, Cam. 



Pig. 9. — Reconstruction of the pelvic fin of an embryo 28 mm. long. The 

 precartilage skeleton is represented complete; the anterior twelve ventral 

 muscle-buds and ten posterior dorsal muscle-buds are indicated. At this 

 stage the base of the muscle-buds is being converted into contractile tissue, 

 which is not represented in the figure. 



Pig. 10. — Reconstruction of a portion of the vertebral column, the skeleton 

 of the first dorsal, and of the pelvic fiu of an embryo 37 mm. long. The cartilage 

 is beginning to develop. 



Figs. 11, 12. — Keconstructions of the first dorsal fin (fig. 11), and the 

 pelvic fin (fig. 12), of the series represented in fig. 10. The muscles are out- 

 lined in red and the skeleton in black. 



