POLYPTEKUS. o 



The vent is situated close to and in front of the anal fin ; on each side of it an 

 abdominal pore, minute and difficult to distinguish, opens under the scaly basal fold 

 of the anal fin. 



The ventral fins are composed of 13 to 16 rays; one of the fins, either the right or 

 the left, is not infrequently longer than the other. 



Apart from the superficial bones of the skull, which afford important specific 

 characters, the skeletons appear to differ according to the species in the number of 



Tiff. 1. 



Caudal region of P. senegalus, female, from Fashoda. Natural size. 

 Fie. 2. 



Caudal region of P. senegalus, male, from Pashoda. Natural size. 



vertebrae, of which there are 64 to 67 (50 or 51 precaudal -+-14 to 16 caudal) in 

 P. bichir, 53 (41 + 12) in P. endlicheri, and 60 (47 + 13) in P. senegalus. 



We owe the first observations on the characters of the young to Dr. Steindachner, of 

 Vienna, who, in 1869, on his return from a collecting-expedition to the Senegal, 

 announced the startling discovery that both P. lapradii and P. senegalus are provided, 

 for a certain period, with a large opercular gill similar in appearance to those possessed 

 by Tailed Batrachians. Since then, numerous specimens provided with external gills 

 have been obtained in the Congo, in the Gambia, in the Niger, and in the Nile. 



b2 



