VOL. IV. | Fresh Water Oligocheta. 21 
geographical distribution, which influences are not interfering 
with the fresh water algze inhabiting the same localities. 
Nearly all the California fresh water oligochzta which have 
been described to date, have been found in single ponds 
or springs, and have been vainly searched for elsewhere. 
Thus in the Mountain Lake, near San Francisco, at the 
Marine Hospital, several forms occur which are not found 
outside of that little pond, as a pond it really is. We may 
mention Sutroa rostrata and Limnodrilus stlvani (long form) 
among others. In Laguna Puerca, which is only a few miles 
from this place, we look in vain for these species, but here 
another species and genus occurs, which again is found nowhere 
else. This genus is a new one, related to Sparganophilus, of the 
family Rhinodrilide. ‘This family is an American one, still one 
species of Sparganophilus has lately been found and described by 
Benham, from a very limited spot in the River Thames, in 
England. Mr. Benham is convinced that the cocoons of this 
worm have been brought there with American plants, as the 
locality where the worm is found is, in reality, restricted to a few 
yards square. Swztroa rostrata is similarly restricted, it being 
only found in a place not over a hundred feet square in the pond 
mentioned above. But, if we return to our San Francisco species, 
we find that in Laguna Merced, not over a mile from Laguna 
Puerca, we look in vain for any of the species found in the two 
other ponds. Swutvoa alpestris again has been, so far, only found 
in a few small springs around Donner Lake, in the Sierra Nevada, 
-and I have not been able to find it elsewhere. Ze/matodrilus 
vejdovskyt again has, though extensively searched for, only 
been found in a single meadow in the Sierra Nevada, in Fresno 
County. LEclipidrilus is another remarkable form, found in two 
little springs at Alpine Meadows, on the head waters of the middle- 
fork of King’s River, in the Sierra Nevada. 
Ocnerodrilus occidentalis has only been found in a plat of 
garden one hundred feet square in Fresno County, but nowhere 
else in California, nor have I been able to find any other species 
of Ocnerodrilus in this State. Ocnerodrilus beddardi occurs only 
in the Cape region of Baja California, but does not transgress its 
limits, and does not-reach the main-land of Mexico, across the 
