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THE AMERICAN NATURALIST [Vol. XLIV 



as an element in the plague situation. Its habits and distribu- 

 tion have been outlined by Merriam. 8 who also discusses means 

 for its systematic destruction. 



Much less well known is another California rodent which has 

 very recently been shown to be susceptible to bubonic plague 

 under natural conditions. This species is the woodrat, Neotoma 

 fuscipes annectens Eliot. It is distinctly a new world form, of 

 which several species occur on the Pacific const and into the 

 desert region as far as Utah and Colorado. Evidently, if the 

 infection can be transmitted from one to another of these species, 

 the disease will thus extend over a large area. Rucker, 9 says 

 of their habits : 



Wood rats are nocturnal in their habits and are seldom seen in the 

 light of open day except when it is very cloudy. For the most part, 

 they are found along small wooded arroyos, in which they build their 

 nests, often of the most elaborate design. Those which the writer has 

 had the opportunity of dissecting consist of pieces of driftwood ar- 

 ranged in a pile, sometimes (i or 7 feel in diameter and 3 feet high. 

 There is usually only one entrance to the nest and this is lined with 

 sharp sticks. It is said that where cactus is plentiful the tunnel is 



The interior of the nest is frequently arranged fnto three stories, and 

 contains storehouses and living rooms. Usually there is an exit which 

 is frequently found near the base of a tree. This is utilized as a means 

 of escape when the ordinary entrance is blocked and some enemy begins 

 to tear the nest apart. The storehouses in several instances contained 

 large quantities of the conns of a plant growing in the immediate 

 neighborhood. Although wheat was g TOW ing but a few hundred yards 

 away, none of this was found in these nests. In certain regions the 



are raided annually by the Indians, who use them for food. They also 

 store up mushrooms, certain varieties of puffballs and acorns. 



In view of the part played by fleas in the transmission of the 

 disease, it is interesting to note the average number of fleas from 

 a squirrel is much larger than from a rat or from any other host 

 yet observed. Much collateral work has been done on the species 

 of fleas, found on the various rodents which suffer from bubonic 

 plague, and on the relations of these fleas to the transfer of the 

 disease as shown by their ability or readiness to bite man and 

 other hosts. The majority of the two rat fleas common in San 

 Francisco, viz., LwmopsyUa chcopis Roth and Ceratophyllus 



""Public Health Reports," Vol. 23, No. 52. 

 ""Public Health Reports," Vol. 25, No. 1, p. 2. 



