GENITAL SYSTEM OF LYCTUS BRUNNEUS. 595 
Arising as an invagination of the eiglith sternite and extending into the 
inetathoras is the long, flexible, and stcongly-chitinized cloacal stalk, from 
which arise systems of muscles for exserting and withdrawing the ovipositor. 
These muscles are found to be modified intersegmental muscles. 
Murphologicully the gonopore in both sexes was found to arise medianly 
on the ninth sternite, and the homology of the genitalia appears. 
In the larva of L. hrunneus there are nine pairs of spiracles, one thoracic 
and eight abdominal ; in tlie adult there are also nine pairs, two thoracic and 
seven abdominal. 
The movement which the rectum of the female is subjected to has been 
observed to be injurious to this organ, in that, lacking any muscuktory 
system for its withdi-awal, other than its muscular structure, it was found 
convoluted inside the "ovipositor" of an egg-laying specimen. This 
defectiveness must accelerate death. 
Acknowledgments. 
The economic investigation, of which this paper records part of the results, 
was suggested by Prof. H. Maxvvell-Lefroy, Imperial College of Science, to 
whom the writer has to express his thanks, and to the Commitfoe of the 
Scientific Industrial Research Dept. for a grant to carry on the work. 
The writer is also indebted to Dr. CJ. J. Grahan, Keeper of the Department 
of Entomology, British Museum (Nat. Hist.), for identifying specimens 
of L. hrunneus ; to Dr. Hugh Scott, Cambridge Museum, for specimens of 
L. linearis ; and to M. P. Lesne, Mus. Nat. d'Hist. Nat., Paris, for very 
kindly sending some oak thought to be infested with L. linearis. 
In addition, tha'nks are due to Dr. A. D. Imms, Rothamsted Experimental 
Station, for his advice and for his assistance in connection with the publi- 
cation of this paper ; and to Prof. Stewart MacDougall for his efforts to have 
the original paper published as a whole. 
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