LEPIDOSIREN— PROTOPTERUS. 15 



possessed a functional lung, and was reckoned as a Reptile, or as what we should now 

 more distinctively term a Perennibranchiate Amphibian. 



Within two years from the publication of Fitzinger's new species {Lepidosiren 

 paradoxa), another nearly allied animal from Senegambia was submitted to Prof. Owen for 

 examination. He was at first disposed to regard it as a new genus, and in the Manu- 

 script Catalogue of the Museum of the Royal College of Surgeons he assigned to it the 

 name of Protopterus, but the perusal of Natterer's account of Lepidosiren paradoxa after- 

 wards led him to unite the two species in one genus. Ultimately the points of difference 

 appeared to be of generic importance, and the name of Protopterus was revived for what 

 was first named in print Lepidosiren annectens. Meanwhile Peters 1 had proposed the 

 name of Rhinocryptis, which is thus a third synonym in use. 



Professor Owen came at once to the conclusion that Lepidosiren and Protopterus 

 were not Amphibia, but Fishes, resting this conclusion on the supposed absence 

 of any communication between the nasal sacs and the mouth. A long controversy 

 ensued, in the course of which every part of the structure of the fishes in question 

 was minutely scrutinised. The amphibian determination was supported by Natterer, 

 Fitzinger, Bischoff, and Gray. 2 Milne-Edwards less decidedly took the same side. 

 Agassiz, 3 Muller, Hyrtl, and Peters' 1 regarded the piscine characters as predominant, and 

 their arguments have finally prevailed. 



It is not needful to review in all its details an extinct controversy. Lepidosiren and 

 Protopterus present the following decisive characters, each found in unquestioned Fishes, 

 and none in any recent adult Amphibian or Reptile : 



1. Persistent notochord; no intervertebral cartilages. 



2. No occipital condyles ; notochord entering the skull. 



3. Vertical fin -rays. 



4. Dentition consisting of a pair of vomerine teeth, and two pairs of opposed dental 

 plates. 



5. Persistent internal gills. 



6. No distinction of large and small intestine. 



The Protopterus of Tropical Africa is now known to frequent the river Gambia, the 

 Senegal, Niger, Zambesi and Nile. All these streams are more or less intermittent. 

 When the waters retreat the Protopteri which may be left upon the bank bury them- 

 selves in the mud, leaving however a small aperture for communication with the air. 

 As the mud dries and cracks in the sun the fishes become enveloped in earthy cases 

 lined by a thick mucous secretion. In this state they remain until the return of the 

 rainy season enables them to escape and swim about again. The more obvious pecu- 



1 ' Monatsbericht der Akademie der Wissenschaften zu Berlin,' 1844, p. 414. 



2 'Proc. Zool. Soc.,' 1856, p. 342. 



3 'Poissons Fossiles,' vol. ii, pt. ii, p. 46. 



4 ' Midler's Arcliiv.,' 1845, §§ 1—14. For further references, see pp. 13, 14. 



