PLATE XXX. 



Class-OYCLOSTOMATA. 



THE HAG-FISH (Myxine glutinosa). 



FIG. 1. DISSECTION FROM THE VENTRAL ASPECT, x f . 



n. nostril surrounded by tentacles : m. mouth : o. oesophagus 

 p. branchial pouches : h. heart : 1. liver : i. intestine : a. anus ; 

 ov. ovary : e. eggs : tn. g. mucous glands. 



FIG. 2. BRANCHIAL SYSTEM, x . 



o. cesophagus : i. internal branchial ducts : b. branchial pouches 

 d. external branchial ducts : s. special duct on the left side 

 c. common branchial duct : p. branchial pore : v. ventricle : 

 a. branchial artery giving off a branch to each gill. 



THE EIVER LAMPREY (Petromyzon fluviatilis). 

 FIG. 3. MOUTH, x 1. 



FIG. 4. SIDE VIEW, x 1. 



e. eye : 6. external branchial openings. 



