No. 393.] THE LIFE HABITS OF POLYPTERUS. 723 
along the right (larger) lobe of the so-called lungs. These 
structures open by the common large (about 2 cm. long) glottis 
into the pharynx, and they contain normally about four or five 
hundred cubic centimeters of air. A further discussion of the 
respiratory function of these bladders will be given later, when 
their histology can be discussed ; but their principal resem- 
blance to amphibian or reptilian lungs is shown in the relations 
of the capillaries and the arrangement of the blood vessels 
running to and draining them. 
REPRODUCTION. 
1. Migration. 2. Time and place of breeding. Manner of 
fertilization — size and character of eggs. 3. List of fish as to 
ovaries. 
1. Migration.— Several of the fresh-water fishes found in the 
Nile migrate each season to the Mediterranean to spawn. This 
is the case with the eel (Hanash) and the several species of 
mullets. It has never been supposed that Polypterus could be 
found in any considerable numbers north of the second cataract, 
so that there seemed to be little likelihood that this fish migrated. 
When, however, fish were found in this lower part of the river 
more abundantly than in any other part known, except the 
head waters, it became a possibility that Polypterus had migra- 
tory habits. Investigation of the distribution of Polypterus at 
points intermediate to the second cataract and the mouth 
showed that in the large brackish Lake Menzaleh, an enlarge- 
ment of the Delta, no adult fish could be got, although it 
was reported that two young Polypteri were obtained here 
the year before. The single specimen in the Natural History 
Museum at Cairo was the only one which had been seen in the 
local markets there for a number of years. At Assiout, 325 
miles from the sea, the fishermen did not recognize the stuffed 
specimen shown them, but when the name, ‘“aboubichir,’’ was 
mentioned they said that such a fish was occasionally found 
there ; that it came from bad crocodiles’ eggs and went down 
the river, while the good eggs brought forth young crocodiles 
that went up river! 
