APPENDIX 573 



liver ; metapleural folds ; dorsal fin (Fig. 239) ; in the intes- 

 tinal region, myotomes, notochord, and spinal cord ; intestine ; 

 dorsal aorta, subintestinal vessel ; anal fin (Fig. 241). 

 11. Examine either specimens or wax models illustrating the 

 development (Figs. 358, 363). 

 The Dogfish will usually not be procurable alive. 



It can sometimes be observed in an aquarium. 

 The Oogrfish.i 2a. In ventral view of specimen, whose belly may have 



been opened to let in preserving fluid, note : nasal 

 openings, oronasal grooves, mouth ; cloacal open- 

 ing ; pectoral fins, pelvic fins, with claspers in 

 male ; anal and caudal fins (Fig. 252). 

 b. In side view, note : head, trunk, and tail ; eye, mouth, 

 spiracle, gill-clefts ; lateral line ; pectoral, pelvic, dorsal, 

 caudal, and anal fins (Fig. 245). 

 3<z. Strip off a small portion of skin to show myomeres (Fig. 247). 



b. Examine scales under lens (Fig. 246). 



c. Examine teeth. 



4. In a ventral view of the contents of the abdominal cavity, 

 note : falciform ligament, with internal opening of oviducts 

 in female and vestige of same in male ; bilobed liver, gall 

 bladder, bile duct ; cardiac and pyloric divisions of stomach, 

 bursa entiana, intestine, rectum ; pancreas and its duct ; 

 rectal gland ; spleen (Fig. 252). 



5«. Turn the liver forward and alimentary canal to the left, and 

 note in addition : cceliac artery, portal vein, testis or ovary, 

 vas deferens or oviduct. 



b. Remove the alimentary canal and its appendages, cut open the 



cloaca, remove the dorsal peritoneum on one side. Note : in 

 male, testes, vasa efferentia, vas deferens, vesicula seminalis, 

 sperm sac ; kidney ; cloaca, anus, urinogenital papilla, ab- 

 dominal pouches ; in female, ovary, oviduct, its internal and 

 cloacal openings, shell gland ; kidney, its duct and bladder ; 

 urinary papilla ; abdominal pouches (Figs. 254, 255). 



c. Cut open the intestine, wash out, and examine the spiral valve. 

 6a. Open the pericardium. Note : sinus venosus, auricle, ventricle, 



conus, ductus Cuvieri (Figs. 252, 257). 



b. Pass a seeker, behind the heart, through the pericardio- 



peritoneal canal. 



c. Cut open sinus venosus and ductus Cuvieri and find openings 



of : hepatic, posterior cardinal, and anterior cardinal sinuses. 

 7a. 2 Skin the throat and dissect away underlying sheet of muscles. 



1 The Piked Dogfish (Acant/iias vulgaris), sometimes used for dissection, differs 

 from the rough hound only in comparatively unimportant points. It is rather 

 smaller, and more slender, and has a sharp spine in front of each dorsal fin. Its 

 oronasal grooves are closed, the gall-bladder is more and the thyroid less con- 

 spicuous, the pancreas is variable in size, and both ovaries are present. The fourth 

 and fifth afferent branchials have a common root. The ophthalmic branch of the 

 fifth nerve passes ventral to the superior oblique muscle and is therefore probably 

 the ophth. profundus, and the maxillary and mandibular branches separate earlier. 



2 Parts of the arterial system missed in the dissection owing to lack of blood in 

 preserved specimens should be identified in injected specimens. 



