18 PEOF. E. EAT LANKESTEE ON LEPIDOSIEEN AND PEOTOPTEEUS. 



and the vascularity of the villi are in favour of the supposition that the cavernous tissue 

 may be erectile under certain conditions, probably at the time of sexual congress '. 



External Gills of Protopterus. 



The presence of external gills was given in the Brit. Mus. Cat. Fishes, viii. p. 322 

 (1870), by Dr. Giinther, as diagnostic of the genus Protopterus in contrast to Lepidosiren. 

 The diagnostic is adopted also by Schneider (loc. cit.). I believe that the distinguished 

 zoologist of the British Museum would not at the present moment put forward that 

 character as one to be insisted upon. There is no doubt that moderate-sized specimens 

 of Protopterus, such as that figured in PI. II. fig. 2, do not possess external gills. 

 While small specimens of Protopterus possess remarkable pigmented (yellow and 

 black) external gills, it is impossible at present to use this character as distinguishing 

 Protopterus from Lepidosiren, since small specimens of Lepidosiren have not been 

 examined, and may therefore, for all we know, possess such gills also. 



The Specimen q/" Protopterus arxnectens, figured in Plate II. fig. 2. 



The Protopterus figured in the Plate accompanying this paper, for the purpose of 

 comparison with Lepidosiren, was living in the tank of the Reptile House in Regent's 

 Park three hours before it was sketched. The drawing has a special value, therefore, 

 as being made from a perfectly fresh and undistorted specimen. It was kindly placed 

 in my hands for the purpose of study by Dr. P. L. Sclater, Secretary to the Zoological 

 Society of London. It proved to be a female, and is one of six from the Gambia River 

 presented to the Society by Mr. H. H. Lee. 



It is remarkable that both the limbs and the tail of well-grown specimens oi Protopterus 

 seem to be specially liable to injury during life. I believe this injury arises not only 

 from bites inflicted by the Protopteri on one another, but also from the attacks of a 

 parasite which is allied to, if not identical with, the Saprolegnia ferox of salmon 

 disease. In captivity they are, as a fact, attacked by Saprolegnia, and the consequent 

 ulceration leads to loss of parts of the caudal and lateral fins. 



The female specimen which is drawn in PI. II. fig. 2 is remarkable for the complete- 

 ness of the caudal fin and for the fact that a minute median filament is present, 

 extending beyond the main outline of the fin posteriorly. 



I am not able at present to give any further detail as to the nature of this process, 

 the specimen being retained in a complete condition for exhibition in the University 

 Museum, Oxford. 



The lateral fins are of more than average length as compared with specimens of this 

 size. In young Protopteri the pectorals and pelvics are very long; in specimens 



' A demonstration that such is the nature of the villi would, however, require specimens in which the 

 condition of turgescence was actually retained in preservation, or fresh specimens upon which injection could 

 he practised. 



