35 
lu 1837 an undescribed fish was sent to the Vienna 
Museum from the river Amazons. It was examined by 
Fitzinger, who named it Lepidosiren paradoxa, placing it, as 
we now see, erroneously, in the class of Beptiles, but calling 
attention at the same time to its piscine afiinities. It com- 
pletely resembled a fish in external form, except that 
attenuated processes, cylindrical and pointed, occupied the 
position of the pectoral and ventral fins. It further possessed 
true gills, blind nasal sacs, a spiral valve in the intestine, 
besides a vertebral column and an organ of hearing compar- 
able only to those of a fish. But it was found to be furnished 
with a true paired lung, which communicated with the 
oesophagus by an airduct closed with a glottis, and received 
venous blood from the heart, returning it as arterial. This 
last hint as to its affinity was regarded for a time as 
decisive. The presence of a functional lung was then held to 
be the one test sufficient to separate the class Reptilia 
Keptilia + Amphibia of modern naturalists) from the 
class Pisces. Lepidosiren 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 Pitzinger's new 
species Lepidosiren paradoxay another nearly allied animal 
from Senegambia was submitted to Professor Owen for ex- 
amination. He was at first disposed to regard it as a new 
genus, and in the manuscript catalogue of the Museum of 
the College of Surgeons, he assigned to it the name of 
Frotoptenis, but the perusal of JSTatterer's account of Lepi- 
dosiren paradoxa afterwards led him to believe the two 
species to be generically identical. Ultimately the points of 
difference appeared to be of generic importance, and the 
name of Protoptenis was revived for what was first named 
in print Lepidosiren annectens. Meanwhile Peters* had pro- 
* Monatsbericht der Akademie der Wissenschaften zu Berlin, 1844, p. 414, 
