302 SUMMARY OF CURRENT RESEARCHES RELATING TO 



normal direction of their pedal waves. By the use of a manometer 

 it was shown that pedal waves are areas of suction, and therefore 

 concavities. J. A. T. 



Pedal Locomotion of Aplysia californica. — G. H. Parker {Jonrn. 

 Exper. Zool., 1917, 24, 139-45, 1 fig.) finds that pedal locomotion in 

 this sea-hare " is due to monotaxic retrograde waves, which lift the foot 

 locally and temporarily from the substrate, enabling it thus to move 

 forward with freedom, while the rest of the foot for the time being 

 holds the snail in place by many small areas of local suction." J. A. T. 



Arthropoda. 

 a. ^nsecta. 



Insects and Disease. — Malcolm E. MacGregor {Trans. Amer. 

 Micr. Soc, 1918, 37, 7-17. See also Journ. Tropical Medicine and 

 Hygiene, 1917, 20) publishes five provisional tables showing the part 

 that insects play in spreading diseases of unknown origin (like trench 

 fever), of bacterial origin, of spirochsetal origin, of Protozoan origin, 

 and of Helminth origin. A fifth table shows the more important 

 diseases directly attributable to insects and Acarina. Much of our 

 knowledge with regard to insects and disease is still indefinite, but the 

 author's tables, which are in no way dogmatic, afford striking illustration 

 of the multiplicity of inter-relations. J. A. T. 



Wing-markings of Arctiidae.— J. F. van Bemmelef {Proc. R. 

 Acad. Sci. Amsterdam, 1918, 20, 849-60) finds in a study of Arctiidse 

 additional evidence in support of his view that there was for Rhopalocera 

 and Hepialids an original pattern, common to all members of the group, 

 and modified in various but not independent ways in the several 

 families, genera and species. The colour-pattern of Arctiidse may be 

 deduced from an ancestral fundamental form, in which a light ground 

 is divided into seven fields by a corresponding number of transverse 

 rows of dark spots, running uninterruptedly from fore to hind margin, 

 on both sides of the fore as well as of the hind wings. It represents 

 not the primitive Lepidopterous pattern but the secondary He])ialid 

 design. No fundamental control exists between ground colour and 

 markings ; they have a common origin, and become altered in the same 

 way by similar influences. J. A. T. 



Wing-venation of Lepidoptera.— R. J. Tillyard {Proc. Linn. Soc. 

 N.8.W., 1917, 42, 167-74, 7 figs.) describes the wing of a Triassic 

 fossil insect which represents a generalized type called " Protome- 

 copterous," and is regarded as near the ancestral stock of the four 

 orders Mecoptera, Trichoptera, Lepidoptera and Diptera. J. A. T. 



Observations on Caterpillars of Cabbage-white Caterpillars. — 

 Cl. Gautier {C.R. Soc. BioL, 1918, 81, 196-7) has seen these cater- 

 pillars regurgitate the well-known green syrupy alimentary content 

 to a distance of 4 cm. The fluid shows nutritive particles, occasional 



