600 



THE AMERICAN NATURALIST 



[Vol. XLI 



The Suboesopkageal Body of Insect Embryos. — The question as to- 

 the origin and the morphological significance of the suboesophageal 

 body which has been found in certain insect embryos is an open one. 

 Hirschler* has studied this structure in embryos of Donacia and has 

 added much to our knowledge of its nature. He finds that it is ento- 

 dermal in origin and that from an unpaired rudiment at the end of 

 the stomadeal invagination there arise four rounded, paired masses 

 which finally communicate directly with the lumen of the mid-intestine. 

 These persist until at least the third day of larval life — their further 

 fate has not been studied. 



Hirschler's results apparently confirm the theory of Nusbaum and 

 Fulinski, '06, that the suboesophageal body is to be homologized with 

 the hepatopancreas, or glandular diverticula of the mid-intestine, of 

 the Crustacea. 



Stridulation Rhythm of Crickets.— According to A. F. Shull (Can. 

 Ent., vol. 39, p. 213), in the chirping of the snowy cricket "exact 

 synchronism is comparatively rare" and exists only between two or 

 three neighboring individuals. Thus two crickets five feet apart were 

 observed to time their chirps in unison as if they heard each other. 

 The rate of stridulation is independent of wing length; in general it 

 increases with rise in temperature, but Dolbear's and Bessey's formulae 

 to express this relation are only approximately correct. Under the 

 same conditions the rate in different individuals varied from 93 to 110 

 chirps per minute. Except on cool nights, from 600 to 800 chirps 

 are usually performed continuously; one cricket was found to chirp 

 2,640 times without interruption. 



Notes.— Bull. 110 of the X. Y. State IVIuseum, preparatory to a 

 monograph of the Cecidomyiidae, presents descriptions of 203 new 

 species belonging to this group. The Cecidomyiidae, or gall gnats, 

 are dipterous insects from 0.5 to 3.0 mm. in length which produce 

 various leafy galls including tlie "willow cones." Bull. 109 of the 

 \. Y. State Mu^rum is devoted to the tussock moth and rim leaf beetle. 



W. A. Riley. 



' Hirsehler, J. 

 Entuickhmf,' l>ei 



im., 1907, 31, pp. 766-770. 



und ihre embryonale 



