DESCRIPTION OF PLATES IV AND V. 



PLATE IV. 



Fig. 1. — Transverse section through the pelvic fin of an embryo of 

 Scyllium belonging to stage P/ magnified 50 diameters, hp, basipterygium ; 

 hr^ fin-ray ; m. muscle ; hf, horny fibres supporting the peripheral part of 

 the fin. 



Fig. 2. — Pelvic fin of a very young female embryo of Scyllium stellare, 

 magnified 16 diameters, bp, basipterygium ; pu, pubic process of pelvic 

 girdle (cut across below) ; il, iliac process of pelvic girdle ; fo, foremen. 



Fig. 3. — Pelvic fin of a young male embryo of Scyllium stellare, magni- 

 fied 16 diameters, bp, basipterygium ; mo, process of basipterygium con- 

 tinued into clasper ; il, iliac process of pelvic girdle ; pu, pubic section of 

 pelvic girdle. 



Fig. 4. — Transverse section through the ventral part of the trunk of an 

 embryo Scyllium of stage P, in the region of the pectoral fins, to show how 

 the fins are attached to the body, magnified 18 diameters, br, cartilaginous 

 fin-ray; ^^, basipterygium ; m, muscle of fin; mp, muscle-plate. 



Fig. 5. — Transverse section through the ventral part of the trunk of an 

 embryo Scyllium of stage P, in the region of the pelvic fin, on the same 

 scale as fig. 4. bp, basipterygium ; br, cartilaginous fin-rays ; m, muscle of 

 the fins ; mp, muscle-plate. 



PLATE V. 



Fig. 6. — Pectoral fin of an embryo of Scyllium canieula, of a stage be- 

 tween and P, in longitudinal and horizontal section (the skeleton of the 

 fin was still in the condition of embryonic cartilage), magnified 36 dia- 

 meters, bp, basipterygium (eventual metapterygium) ; fr, cartilaginous 

 fin-rays ; pg, pectoral girdle in transverse section ; fo, foramen in pectoral 

 girdle; pe, epithelium of peritoneal cavity. 



Fig. 7. — Transverse section through the pectoral fin of a Scyllium 

 embryo of stage P, magnified 50 diameters, bp, basipterygium ; br, carti- 

 laginous fin-ray ; m, muscle ; hf, horny fibres. 



Fig. 8. — Pectoral fin of an embryo of Scyllium stellare, magnified 16 dia- 

 meters, mp, metapterygium (basipterygium of earlier stage); me.p, rudi- 

 ment of future pro- and mesopterygium ; sc, cut surface of a scapular 

 process ; cr, coracoid process ; fo, foramen ; hf, horny fibres. 



Fig. 9. — Skeleton of the pectoral fin and part of pectoral girdle of a 

 nearly ripe embryo of Scyllium stellare^ magnified 10 diameters, mp, meta- 

 pterygium ; mes, mesopterygium ; pp, propterygium ; cr^ coracoid process. 



' I employ here the same letters to indicate the stages as in my Mono- 

 graph on Elasmobranch Fishes. 



