[25] OLIGOCH^TOLOGICAL RESEARCHES. 903 



baiuty tliat the climate of California, dry as it is, is gradually oliauging^ 

 to a damp oue, and that for the following reasons : 

 jl If Middle and Southern California in former, not to say distant, ages 

 had enjoyed a moist and rainy climate, its soil in favorable places would 

 most likely contain numerous earth-worms. I naturally judge this 

 from analogy, as there is no country which is not absolutely dry for any 

 length of time where earth-worms are wanting. If now, therefore, the 

 climate of California began to get drier, the worms formerly distributed 

 over the whole of the country would naturally recede to the remaining 

 moist land around the water-courses, and, finding here the necessary 

 conditions for existence, remain to the present day. 



But in Middle and Southern California I have hunted in vain for 

 native Liimhricides, and even so in the always moist earth around King's 

 and San Joaquin Rivers, places at present climatically isolated. From 

 these facts I draw the conclusion that even in former time no climatical 

 connection existed between the said river valleys and other countries in- 

 habited by earth-worms and that the climate, if changing at all, is get- 

 ting moister, being formerly an arid one. 



Around San Francisco and other cultivated places throughout Cali- 

 fornia we find in the gardens several imported European species of 

 earthworms and only one single species which at present is known 

 only from California. 



If similar conclusions can be drawn from the study of LumhricuUdm 

 or terrestrial Oligochceta, it may also be reasonable to suppose that 

 even the geographical distribution of the Limicolide worms will en- 

 lighten us upon subjects related to a country's former geographical 

 and climatological connections. 



It is, of course, as yet too early to speculate further upon these points, 

 or to draw any conclusions from the few with certainty known facts, 

 but I have here only wished to call attention to the importance of the 

 geographical distribution of this class of animals, and, which of course 

 is partly the same, to the study of their diftereot species. 



While many classes of animals exhibit both more attractive features, 

 more gorgeous colors, and are more easily studied, they therefore in no 

 way are any more valuable to the science of natural history, and it 

 would even be well if scientific expeditions and private collectors would 

 more generally and with more generosity di\dde their attention between 

 the popular and not popular classes of the animal kingdom. 



But, returning to the geographical distribution of the species, we 

 find that about 22 species of TuUficidoe are as yet known, and about 

 equally divided between Europe and iSForth America, provided we only 

 consider species which are sufficiently well described to be recognized 

 and classified. 



Among species as yet iusufdciently known I consider Scemiris abys- 

 sicola, Scmuris limicola, TuMfex profimdicola, Chirodnllus larvceformis, 



