136 BUEEDlXG-HAHrrs OF SOME WEST-AFKKJAX FlSUE.i. 



PLATE XI. 



Fii. 1. Larva of I'olypterus lapradei Stein., 1^ inch in length, magnification about four 



diameters showing the very large external gill of the hyoid arch, situated immediately 



behind the spiracle, the blood-supply to the same from the ventral aorta, and the 



very lar»e size of the head and tail-region of the body, also the dorsal fin not broken 



up into finlets. The larva is drawn in a very characteristic attitude as observed when in 



the aquarium. The smallness of the alternate branches of the gill and their different 



position is not shown. 

 Fig. 2. External gill of Polypterus lapradei, showing the difference in size of each gill-branch : 



p. 118. 

 Fi°-. 3. Larva of Protopterus annectens Ow., a few days after leaving the nest, about one month 



old. The larva was killed when its chromatophores were neither fully expanded nor fully 



contracted. The first pair of external gills has been lost and metamorphosis is nearly 



complete : p. 124. 

 Fitr. 4. Larva of Gi/mnaixhus niloticus Cuv., one week after it was laid, two days after hatching, 



showing external gill-filaments, blood-vessel to and from yolk-sac, and the completely 



diphycercal tail : p. 127. 

 Fig. 5. Larva of Gymnarchvs, four days later, showing long drawn-out yolk-sac and abundant 



external gill-filaments. The fin-folds of the tail are shown, and the first trace of 



differentiation of the tail to form the whip-like feeler : p. 127. 

 Fig. 6. Larva of Heterotis niloticus Cuv., one day after hatching, showing external gill-filaments, 



backward extension of the yolk to the cloaca, the pectoral fins, four branchial arches, 



developing operculum, and heterocercal rays in the tail : p. 129. 

 Fig. 7. Larva of Heterotis. dorsal aspect, in order to show relations of operculum, gills, and 



pectoral fin : p. 129. 

 Fig. 8 Larva of Sarcodaces odo'e BL, just after hatching, showing the large adhesive organ borne 



on the front of the head : p. 130. 

 Fig. 9. The same, frontal aspect, to show the form of the adhesive organ : p. 130. 

 Fig. 10. Larva of Hyperopisus bebe Lacep., showing the four dorsal and two frontal cement-organs, 



the auditory sacs, and prominent gill-folds : p. 131. 



