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Arr. II. — Description of a new Spei of Polypterus, from 
West Africa. By W. O. Ayres. Boston, Mass. 
Tue rivers of Africa, which had previously yielded two 
species of the remarkable genus Polypterus, have now 
afforded another. A specimen, brought by Mr. Perkins 
from Cape Palmas, and presented to the Boston Society of 
Natural History by him, is undoubtedly a representative of a 
new form. It is readily distinguished from the bichir and 
senegalus by the small number of dorsal fins. A specific 
name derived from its origin will not be inappropriate, more 
particularly as Cuvier has adopted the same course in regard 
to the one received by him from Senegal. It may be called 
P. palmas. 
Its form is elongated, depressed at the head, nearly cir- 
cular at the pectorals, and thence gradually becoming more 
and more compressed. The entire length is nine inches and 
three tenths; the greatest depth, about midway of the length, 
an inch; breadth at the same place, six tenths; breadth of 
the head, eight tenths. The specimen is quite manifestly 
full grown, or nearly so, and it is worthy of note that both 
the species discovered in West Africa are small while the one 
which inhabits the Nile is of much greater size. 
One of.the remarkable characters of the fishes constituting 
this genus is the strong lorication of nearly every portion of 
the surface. The plates which shield the head are granu- 
lated or shagreened. Those covering the upper portion of 
the head in this species are eight, arranged somewhat in 
pairs, though those of one side do not precisely match those 
of the other in position or size. The operculum is irregularly 
quadrangular, narrowest in front, arcuated posteriorly, nine 
twentieths of an inch in length. The pre-operculum, shorter 
and narrower than the operculum, is situated immediately 
in front of it. The inter-operculum, triangular in shape, is 
inserted between the two preceding pieces, with its base 
