VOL. IV.] Fresh Water OligochcEta. 21 



geographical distribution, which influences are not interfering 

 with the fresh water algae inhabiting the same localities. 



Nearly all the California fresh water oligochseta 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 lyake, 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 silvani (long form) 

 among others. In I,aguna 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 Rhinodrilida. 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. Szitroa rostrata is similar!}' 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. Sutroa alpestri's 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. Telmatodrilus 

 vejdovskyi again has, though extensively searched for, only 

 been found in a single meadow in the Sierra Nevada, in Fresno 

 County. Eclipidrilus 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 



