EXPLANATION OF [PLATE 33]. (XX. p. 714.)
Fig. 1. Transverse section through the pelvic fin of an embryo of Scyllium belonging to stage P[5], magnified 50 diameters. bp. basipterygium. br. 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. foramen.
Fig. 3. Pelvic fin of a young male embryo of Scyllium stellare, magnified 16 diameters. bp. basipterygium. mo. process of basipterygium continued 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 shew how the fins are attached to the body, magnified 18 diameters. br. cartilaginous fin-ray. bp. 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.
Fig. 6. Pectoral fin of an embryo of Scyllium canicula, of a stage between O and P, in longitudinal and horizontal section (the skeleton of the fin was still in the condition of embryonic cartilage), magnified 36 diameters. 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. cartilaginous fin-ray. m. muscle. hf. horny fibres.
Fig. 8. Pectoral fin of an embryo of Scyllium stellare, magnified 16 diameters. mp. metapterygium (basipterygium of earlier stage). me.p. rudiment of future pro- and mesopterygium. sc. cut surface of a scapular process. cr. coracoid process. fr. 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. metapterygium. mes. mesopterygium. pp. propterygium. cr. coracoid process.