122 MR. G. A. BOULENGER ON THE [Feb. 18, 



We can now distinguish ten Polypteri : — 



1. P. bichirGeo&r. — Mle. 



2. F. laptxcdii Stclr. — Senegal, Gambia, Niger. 



3. P. congicus Blgr. — Congo, L. Tanganyika. 



4. P. endlicheri Heck. — ISTile, Niger. 



5. P. delhezi Blgr. — Congo. 



6. P. ornatipinnis Blgr. — Congo. 



7. P. loeeksii Blgr. — Congo. 



8. P. senegalus Cuv. — Nile, L. Rudolf, Senegal, Gambia, 



Niger. 



9. P. palmas Ayres. — West Africa, from Liberia to the 



Congo. 

 10. P. retropinnis Yaill. — Congo. 



Not before 1869 was anything known of the characters of the 

 young. We owe the first observations on this subject to Stein- 

 dachner \ who, on his return from a collecting expedition to the 

 Senegal, announced the startling discovery that both P. lapradii 

 and P. senegcdus are provided, for a certain period, with a large 

 external opercular gUl similar in structure to those possessed by 

 Tailed Batrachians. In 1896 ", I noticed the presence of external 

 gills in P. palmas, and successively in specimens of P. congicus, 

 lapradii, and toeeksii ^ In his highly interesting memoir on the 

 Breeding-habits of some West- African Fishes "', Mr. Btidgett has 

 made us acquainted with the external appearance of a specimen, 

 referred by him to P. lapradii (but which he informs me, after 

 examination of the Nigeria specimens sent by Dr. Ansorge, 

 should be referred to P. senegalus), smaller than any pi'eviously 

 obtained and which may be regarded as truly larval. Having 

 recently received, from various sources, a number of young- 

 specimens from the Nile, the Congo, and Nigeria, I am able to 

 supplement oui- present knowledge on various points. The notes 

 here offered deal with six species : P. Ia2)radii, P. congicus, 

 P. endlicheri, P. weeksii, P. senegalus, and P. palmas. It will be 

 observed that the young of P. bichir, the oldest known species, 

 the only one to occur in the Lower Nile, is still undescribed. 



Before proceeding to descriptive details, I wish to observe that 

 the specimens with external gdls at present known may be 

 arranged in three divisions: — (1) Without scales, and with the 

 dorsal fin spineless, not difierentiated from the caudal ; the only 

 example known being the larval specimen of P. senegalus, bi-ought 

 home from the Gambia by Mr. Budgett and described and figured 

 by him. (2) With scales of a cycloid type and with the doisal 

 fin as in the preceding. (3) With all the essential charactei's 

 of the mature form. Although the scales may, in the very 



1 Sitzb. Akad. Wien, lix. i. 1869, p. 103. 



2 Ann. & Mag. N. H. (6) xvii. 1896, p. 310. 



3 Ann. & Mag. N. H. (7) ii. 1898, p. 419, and P. Z. S. 1898, p. 493, 1899, p. 554, 

 1900, p. 267. 



■» Trans. Zool. Soc. xvi. 1901, p. 115. 



