322 



THE ELASMOBRANCH FISHES 



Depressor mandibulae, 105 



Depressor rostri, 105 



Dermal fin-rays, 89, 94 



Dermal papilla, 30 



Dermatome, 96 



Dermis. See Corium 



Digestive tract, 121-126; 127-142; ar- 

 teries to, 166-168, 186-191; develop- 

 ment of, 127-128; mesenteries of, 121, 

 127; veins of, 200-201, 210-212 



Diencephalon, 221, 230-233; cavity of, 

 236; outgrowths from, 233 



Digitiform gland. See Eectal gland 



Dilator muscle of sac, 95, 111, 112 



Dilator spiraculae, 102-103 



Diphycercal, 74 



Diplospondyly, 51, 72, 74; function of, 

 74; incomplete, 49 



Bisceus thayeri, 10, fig. 21 



Diverticula of spiracle, 148, 153 ; nerve to, 

 153 



Dorsal aorta, 165-166, 186; development 

 of, 186; paired, 165, 186; tributaries 

 of, 166, 186; unpaired, 165, 186 



Dorsal bundles, 89, 96, 99 



Dorsal constrictor muscles, 90-91, 102- 

 104 



Dorsal cutaneous vein, 202, 203, 216-217 



Dorsal fin, 6, 12, 14; in notidanids, 6; 

 position of, 12 ; skeleton of, 51, 82-83 



Dorsal gastric artery, 187 



Dorsal horn of cord, 222, 237 



Dorsal intercalary plate, 47, 48, 70, 71 



Dorsal intestinal artery, 167, 190 



Dorsal intestinal vein, 200-201, 211; 

 tributaries of, 211 



Dorsal marginal cartilage, 82 



Dorsal myelonal vein, 208 



Dorsal plate, 47, 48, 72; foramen of, 48; 

 incomplete diplospondyly, 49 



Dorsal pterygial vein, 213 



Dorsal root ganglion, 227, 246 



Dorsal root nerve, 227, 246; foramen of, 

 48, 210, 246 



Dorsal spinal vein of ray, 210 



Dorsal suspensory ligament of eye, 270 



Dorsolateral artery, 168, 191 



Dorsolateral bundle, 97 



Dorsomedian bundle, 97 



Duct of Cuvier, 171; tributaries to, 198- 

 199, 200, 202, 205, 210, 212, 214 



Ductless glands, 134 



Ducts of kidney, 294-296 



Ductus choledochus, 124, 137-138 



Duodenum, 124, 136-137; arteries to, 166- 

 167; blind sacs of, 137; derivatives of, 

 136-137; ducts to, 124, 137, 138; mesen- 

 tery of, 121 



Ear, 258-261, 264, 270-274; capsule of, 

 258, 271; development of, 274; nerve 

 of, 261, 273; parts of, 258-259 



Ear stones. See Otoliths 



Ectethnioidal process. See Antorbital pro- 

 cess 



Efferent arteries, 165, 182; branchial, 

 165, 175, 182; development of, 175; 

 hyoidean, 165, 182 



Efferent branchial arterioles, 157 



Efferent-collector arteries, 161-162, 173- 

 177; branches of, 163-165, 178-180; de- 

 velopment of, 175-177; in holobranchs, 

 149, 153, 157, 162 



Egg (ovum), 303; development of, 303; 

 hatching of, 305-306 



Eggshell, 305-306; attachment of, 305; 

 flanges on, 305; perforation of, 306; 

 production of, 305; tendrils of, 305; 

 types of, 305-306 



Elasmobranch fishes, divisions of, 8; se- 

 ries of, 9-10 



Elastica externa, 69, 70 



Elastica interna, 69, 70 



Electric cone, 114 



Electric discs, 112, 113, 114; layers of, 

 114 



Electric nerve, 115, 243, 244 



Electric organ, 112; anatomy of, 114-115; 

 in Torpedo, 115; nerves of, 115, 243, 

 244; origin of, in rays, 114 



Electric ray {Torpedo), 3 



Embryonic aortic arches, 175 ; derivatives 

 of, 178 



Enamel, 30, 32; derived from, 132-133; 

 in rays, 32; nature of, 32; of fin spine, 

 33; of saw tooth, 35; of sting, 37; of 

 teeth, 128, 130; in Carcharias, 132-133 



Enamel organ, 30, 33, 35, 128 



Endolymphatic ducts, 5, 43, 55, 259, 271, 

 272, 273 



Endorachis, 237 



Endoskeleton. See Skeleton 



Ependymal cells, 229-230 



Epiblastic fold, 15 



Epibranchial cartilages, 45, 64, 65, 93, 107 



Epidermis, 23, 28, 30; derivatives of, 28- 

 38; layers of, 23, 26, 30 



Epididymus, 301 



