318 Mr. Kinav's Deferiptions of 
I never could difcover that it had any eyes. When at reft it is 
nearly circular, but when it moves it becomes linear; and then 
the centre of the head is ufually protended into an obtufe angle. 
Its motion (if I may fo exprefs myfelf) is beautifully {mooth and 
uniform; and it is a very amufing fight to obferve thefe little crea- 
tures, in a clear fhallow ftream, on a calm day, by myriads 
fmoothly gliding over its bed. 
At reft it is feldom above one line in length, but extends itfelf 
to three when it moves. 
Found in flow ftreams, I believe almoft the whole year, upon 
aquatic plants. 
3. H. CRENATA. Tab, 29. 
H. fubdepreffa fubovata ftriata ftriis tranfverfis annularibus? mare 
gine crenulato. 
Defeription.—This fpecies is of a greenifh caft, fometimes in- 
clining to ath-colour. It is tranfverfely ftriated with annular ftriz, 
diim whence arife the crenatæ of its margin. 
Its upper furface is fomewhat convex. Its interanea are very 
vifible by means of its vitreous tranfparency; they appear like fo 
many feparate granula. Its excrements I have fometimes feen 
appended to the anus, its form. exactly refembling the interanea; 
they appeared to adhere to.the worm, and to each other, by means 
of a gelatinous tranfparent excretion, which hung in places in ob- 
long guttulz. : 
It has two eyes only, which are very much approximated: 
Its motion is very fimilar to that of the larvæ of the geometræs. 
and 1s performed by means of the adhefive property of the head 
and the tail. The tail being fixed to the fides of the glaís, it ex- . 
tends. 
