180 University of California Publications in Zoology [Vol. 10 



the southeastern deserts are practically without any representa- 

 tives of these groups at all ; a very few, relatively, occur in the 

 southern coast district ; the numbers increase up the Sierra 

 Nevada and towards the northwest, until a state of extreme 

 plenitude is met with in the higher parts of the Sierra Nevada 

 and in the Humboldt Bay region. 



It is evident that these geographic relationships in numbers 

 may show limitation by temperature as well as humidity. Tak- 

 ing numbers of individuals into account, rather than species, 

 though both hold in a way. there appears to the writer to be 

 closest dependence of insectivore population upon dampness of 

 climate if not also upon the permanent presence of standing or 

 running water. 



It may be said of the restricted genus Sores, as far as west- 

 central California is concerned, that all of the six species are at 

 least semi-acpiatic. Their peculiarly interrupted local distribu- 

 tion thus becomes explicable. 



That shrews regularly inhabit the salt marshes of San Fran- 

 cisco Hay was to the writer's knowledge first established in 1908 

 by Mr. Joseph Dixon, who captured a number of specimens in 

 tlif vicinities of Palo Alto and Petaluma in his search for repre- 

 sentatives of the rodent genus Beithrodontomys. Dixon's speci- 

 mens were acquired by Miss Annie M. Alexander and presented 

 by her to the University of California Museum of Vertebrate 

 Zoology, where they form part of the basis of the present paper. 



More recently Miss Alexander and Miss Louise Kellogg dis- 

 covered the presence of shrews in the marshes at the confluence 

 of the Sacramento and San Joaquin rivers. By repeated efforts 

 these collectors obtained for the Museum the series of ten speci- 

 mens enumerated beyond under the description of the remark- 

 able new species Sorex sinuosus. 



From the uplands of west -central California only scattering 

 examples have been seeured, most of these being from the humid 

 coasl belt. Tii show the scarcity of shrews away from the humid 

 coast belt, attention may be called to the fact that in three 

 months' trapping in the summer of 1912, the two Museum col- 

 lectors so engaged found but two specimens of shrews among 

 the many hundreds of small mammals captured. 



