CONTENTS. 



LECTURE X. 



Vascular System of Fishes, p. 246. Absorbents, Lacteals, p. 247. ; Lymphatics, 

 p. 248. Lymphatic Heart, p. 248. Veins, vertebral, p. 250. ; Visceral, p. 251. 

 Portal System, p. 252. Portal Heart of Myxines, p. 252. Hepatic Venous 

 Sinuses, p. 252. Genesis of Blood-discs, p. 253. The Heart, p. 253. Acar- 

 diac Vascular System of Lancelet, p. 254. Pericardium, p. 255. ; its Outlets, 

 p. 255. Homology and Analogy of the Fish's Heart, p. 255. Auricle, p. 256. 

 Ventricle, p. 257. Bulbus arteriosus, p. 257. Heart of Lepidosiren, p. 258. 

 Essential Character of a second Auricle, p. 258. Branchial Artery, p. 258. 

 Comparison of normal Gills of Fishes with Gill-sacs of Myxinoids and Lam- 

 preys, p. 259. Branchial Apertures in Lancelet, Myxine, Bdellostome, Lam- 

 prey, Plagiostomes, and Osseous Fishes, p. 259. Branchiae liberae and Branchise 

 fixse, p. 259. What kills a Fish when out of Water, 260. Modifications of 

 Gill-chamber enabling a Fish to live out of Water, p. 260. Functions of Gills, 

 p. 260. Gills plicated, tufted, pectinated, p. 261. ; uniserial and biserial, p. 261. ; 

 variable Number in bony Fishes, p. 261. Defensive Valves and Processes of Gill- 

 arches, p. 262. Branchial Circulation, p. 263. Development of Gills, p. 264. 

 Hyoid uniserial Gill, p, 265. Retentions of embryonic branchial Structures, 

 p. 266. Deciduous external Gills in Plagiostomes, p. 267. Accessory branchial 

 Organs in the Labyrinthibranchii, in Heterobranchus, in Amphipnous, p. 267. ; in 

 Saccobranchus, p. 268. Arteries, p. 268. Pseudobranchiw, p. 268. Question 

 of their Relations to thyroid Glands discussed, p. 269. Plexus mirabiles in 

 Lamna and Thynnus, p. 271. Spleen, p. 271. 



LECTURE XL 



Pneumatic and Renal Organs. Air-bladder, p. 272. ; its Structure, p. 272. ; and 

 gradual Metamorphosis into a Lung, p. 273. Inconstant Character of the ru- 

 dimental Air-breathing Organ, and of the Ductus pneumaticus, p. 273. ; Vas- 

 cularity of Air-bladder, its Diversities, p. 274. Unipolar Retia mirabilia, 

 p. 275. Bipolar Retia mirabilia, p. 275. ' Air-gland ' present in some Fishes 

 that have the Air-duct, p. 276. Magnus's Discovery of free Gases in Blood, 

 p. 276. Chemical Analysis of Contents of Air-bladders, p. 276. Primary 

 Function of Air-bladder in Locomotion of Fishes, p. 276. ; Objection from its 

 Absence in Sharks obviated, p. 277. Adaptation of Gills and Air-bladder of 

 Lepidosiren to its Habits, p. 278. ; Homology and Analogy of Air-bladder dis- 

 cussed, p. 278. Renal System of Fishes, p. 282. Kidneys of Dcrmopteri, 

 p. 282. ; of Osseous Fishes, p. 282. Urinary Bladder, p. 282. Renal System 

 of Lepidosiren and Plagiostomes, p. 283. Relations of Kidneys of Fishes to 

 the primordial Kidneys of higher Vertebrates, pp. 282. 285. Supra-renal 

 Bodies, p. 285. 



LECTURE Xn. 



Generative System, p. 286. ; its enormous Development and extensive Range of 

 Varieties in Fishes, p. 286. These represent progressively arrested Stages of 

 its Development, p. 286. ; Parallelism in this respect between Male and Female 



