924 The American Naturalist. [November, 
Parker? has shown that Schneider’s second species of Protop- 
terus, P. amphibius is a mistake. Schneider gives the Gambia 
as the habitat of this species. The distinctive characters separ- 
ating this species from annectens are the presence of lateral car- 
tilaginous rays in the fin membranes and only 30 ribs. 
Schneider describes the fins of the Protopterus material which 
Peters brought from Quellimane as long and pointed, but flat- 
tened appendages. This was found to be true of the pectoral 
fin, the pelvic fin being thickened at its base. The cartilagin- 
ous axis of each fin bears on one side several cartilaginous rays 
which support the membranous border of the fin. This border 
is, in turn, stiffened by numerous horny filaments (horn-rays). 
This membrane is found on the ventral edge of the pectoral 
fin. Schneider found cartilaginous rays in P. amphibius only. 
Parker states that his animals were from the Gambia, and 
that the specimens which he “examined for the purpose possess 
in the middle part of the fin, numerous cartilaginous parameres 
on each segment in both fins,” which, according to Schneider, 
is one sure sign of P. amphibius, but Parker’s animals also had 
35 ribs, which is one of Schneider’s marks of P. annectens. 
Parker concludes that there is possibly considerable variation 
in both these structures within the species, and this agrees with 
what Wiedersheim has previously found with respect to the 
FIN MEMBRANES, irrespective of their supporting structures. 
EXTERNAL GILLS. 
Owen,’ McDonnell,’ Schneider? Wiedersheim," Peters and 
Parker’ describe or mention the existence of external gills in 
specimens of Protopterus from the different localities of Africa. 
Owen’s observation has already been referred to. McDonnel 
simply states that he found three processes, rudimentary ex- 
ternal gills the longest of which measurd 4'", 
Boas makes the following statements concerning the exter- 
nal gills of the African mud fish. | 
“Uber die sogenannten äusseren Kiemen von Protopterus 
müssen wir ein Wort sprechen. Die betreffenden Gebilde 
waren bei den zwei von mir untersuchten Protopteri sehr klein, 
