504 ^ CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



animal parasites have been recorded, none of them insects except for the Strep- 

 siptera. Although there are many genera of myrmecophilous and termitophilous 

 lepismatoids, none has been satisfactorily studied in the field. Among the sev- 

 eral domestic Lepismatidae, it is noteworthy that the commonest species, such as 

 Thermohia domestica and Lepis77ia saccharina, are unknown in the original wild 

 state. 



Although investigated more fully than the Entotrophi, the Thysanura are 

 very scantily known. The physiology and cytogenetics are virtually untouched : 

 tantalizing cases of pattern polymorphism in the machiloids await study; the 

 functions of the eversible vesicles, coxal and abdominal styli, and lateral ocelli 

 are unknown or subjects of controversy. A major revision of the classification is 

 urgently needed. The first of the writer's researches on this problem is in press. 

 In almost any region new species may be found. Natural foods are not well 

 known. Behavioral studies are rudimentary, and only recently have the bizarre 

 methods of insemination of one lepismatid and one machilid been described, re- 

 spectively by Sweetman (1938) and Sturm (1952). 



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Grassi, B. 



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Imms, a. D. 



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