NOTES ON THE HABITS OF CERTAIN CRAWFISH. 
BY CHARLES C. ABBOTT, M.D. 
In the course of a day’s fishing during the past month of Sep- 
~ tember, my companion and myself caught a large number of 
those lobster-like crustaceans, known everywhere as ‘¢ Crawfishes ;” 
and by zoologists, as either Cambarus or Astacus, the former 
differing from Astacus in having a more elongated body, “ by the 
absence of the gill on the fifth pair of legs,” and other slight dif- 
ferences, not noticeable except upon careful examination. 
e crawfishes found in New Jersey all belong to the genus 
Cambarus; and of this génus, certainly three species, viz., Cam- 
barus acutus Girard, Cambarus affinis Say, and Cambarus Bartonii 
Fabricius, are found either in the streams and ditches near, or in 
ghe Delaware River, at Trenton, New Jersey. 
It is difficult to say which of the three species is the most abun- 
dant in the general locality we have named, inasmuch as they — 
seem to’ prefer different streams; one being a plant-loving, one 
a stone-haunting, and the third, a mud-frequenting species. In 
their respective haunts, each is apparently as numerous as is 
either of the others in their chosen home. : 
During the past month (September), as a result of a thorough 
examination of many small streams, as well as of the Delaware 
River itself, we have found the Cambarus acutus to frequent — 
running streams, which have masses of vegetation growing in 
them, the animal in question resting upon the plants, usually 
near the surface of the water. We have found since our collect- 
ing excursions, on carefully approaching clear, running streams, — 
ae such as just mentioned, that this crawfish is to be seen resting 
o on the plants always with the head directed down stream. lf 
ao disturbed, they would dart backwards down to the roots, appar- 
ently, of the plant upon which they were sitting. After a 
lapse of about ten minutes they would return to their former — 
resting-place creeping up the plant down which they had so 
suddenly darted tail foremost. 
~ The Cambarus afinis is apparently the river species of this — 
locality. We have been able to find it, as yet, an! in the Dela- 
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