Endoskeleton of Elasmobranchs in General — Continued page 



Appendicular skeleton 75 



Skeleton of paired fins and of fin girdles 75 



Pectoral fin skeleton 75 



Pectoral girdle 79 



Pelvic fin skeleton 81 



Pelvic girdle 82 



Skeleton of unpaired fins 82 



Bibliography 84 



IV. MUSCULATURE 



Musculature of Heptanchus maculatus 89 



Muscles of the eye 89 



Buccal and pharyngeal muscles 90 



Dorsal constrictors 90 



Ventral constrictors 91 



Interarcuales 92 



Adductors 93 



Ventral longitudinal muscles 93 



Muscles of the fins 94 



Musculature of Elasmobranchs in General 96 



Muscles of the eye 99 



Muscles of visceral arches 100 



Superficial constrictors of pharyiLx 101 



Dorsal constrictors 102 



Ventral constrictors 104 



Deeper muscles of pharynx 105 



Interarcuales 106 



Adductores arcus 107 



Hypobranchial musculature 108 



Muscles of the fins 109 



Muscles of the claspers 110 



Electric Organ in Elasmobranchs 112 



Electric organ of rays 112 



Finer anatomy of electric organ 114 



Bibliography .■ •. ^^^ 



V. DIGESTIVE TRACT 



Digestive Tract of Heptanchus maculatus 121 



Mesenterial structures 121 



Buccal cavity 121 



Pharynx and associated structures 122 



Oesophagus 123 



Stomach 123 



Spleen 124 



Duodenum or middle intestine 124 



Valvular intestine 124 



Colon and rectum 126 



Rectal gland 126 



Cloaca 126 



Abdominal pores (Pori abdominales) 126 



Digestive Tract of Elasmobranchs in General 127 



Mesenteries 127 



Buccal cavity 128 



Teeth / 128 



Replacement of teeth • 131 



[viii] 



