352 SUMMARY OF CURRENT RESEARCHES RELATING TO 



as bhe much reduced right olfactory canal, the spermaceti reservoirs, and 

 the structure of the bongue. 



Food of Shrew-mole.* — James A. West has examined bhe stomachs 

 of many shrew-moles (Scahpus aqmlicus) in Illinois. The contents 

 showed perhaps a greater amount of insect food and somewhat smaller 

 ratios of earthworms than those examined by others, but there is sub- 

 Btanl ial agreement to the effect that half or more of the food consists of 

 insects and their larvae, most of them noxious. To this extent, there- 

 fore, it is certain that shrew-moles are beneficial. There is no direct 

 evidence that they attack potatoes or other tubers, but they eat large 

 quantities of corn, and sometimes do considerable damage in fields of 

 newly-planted corn. 



Habits of Shrew-mole.f— F. E. Wood has made a study of Scalopus 

 aquaticus, the common mole of Illinois. The burrows are usually made 

 without bringing earth to the surface. There seems to be one litter in 

 the year, probably with three to six young ones. There is certain 

 evidence of their eating corn. Little is known of their natural enemies. 

 Numbers are often found lying dead, but unmutilated. Many are badly 

 infested with intestinal parasites, e.g. species of Filar ia and Spiroptera. 



Directive Markings of Passerine Birds.J— H. C. Tracy has made a 

 study of the significance of the white markings in birds of the order 

 Pass'eriformes. His investigations were directed mainly towards testing 

 the validity of the older interpretation of white markings in birds— as 

 serving rather as a clue to the direction of the disappearing bird than as 

 an aid" to recognition of the species— by analyzing their mode of occur- 

 rence in a single Order. He finds that there is good ground for believing 

 that markings exposed in flight, whatever their mode of evolution, are of 

 actual utility to birds as sight clues. This is true both of the compara- 

 tively uniform rear markings of open ground species, and of the varied 

 top pattern of arboreal forms. There is a decided correlation of the 

 markings with the habit of flocking, as well as with that of open ranging. 

 He shows that sexual selection can only have operated in producing a 

 more sharply defined pattern in the male, but cannot account for the 

 pattern itself. The newer view (Thayer, 1909) as to the concealing 

 effect of white markings, the author finds to be in perfect accord with 

 the older theory of directive markings, though it limits the application 

 of the latter to patterns that can be shown to be conspicuous. 



The author considers that the interpretation of diverse coloration as 

 having developed under conditions of comparative immunity from attack 

 needs much greater emphasis than has yet been given to it. 



Size of Spleen in Birds.§— Magnan and De la Riboisiere have 

 measured the spleen in a large number of birds. They distinguish two 

 main shapes— ovoid and elongated, and they find that large birds have 

 relatively smaller spleens, and small birds relatively larger spleens. La 

 Riboisiere previously came to the same conclusion as regards weight. 



* Bull. Illinois State Lab. Nat. Hist, ix. (1910) pp. 14-22, 

 t Tom. cit., ix. (1910) pp. 1-13. 



\ Univ. California Publications (Zool.) vi. (1910) pp. 285-312. \ 

 § Ann. Sci. Nat. (Zool.) xiii. (1911) pp. 269-85 (2 figs.). 



