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ORGAN OF THE CAMBRIDGE ENTOMOLOGICAL CLUB. 



EDITED BY B. PICKMAN MANN. 

 Vol. I.] Cambridge, Mass., October, 1874. [No. 6. 



On an Appendage of the male Leucarctia acraea. 



Having occasion recently to examine the male genitalia of 

 this species, I was surprised, on pressing the abdomen forcibly 

 to 'show the parts, to see project from between the lower part 

 of the horny base of the claspers and the flap of skin which in 

 most species is closely adherent to it, two long, singular organs, 

 which I believe have not before been noticed. 



They spring from the base of a pouch which is concealed 

 between the last segments of the body, and formed by the con- 

 tinuation of the external skin. When fnlly distended they are 

 symmetrical, and curve gently downward and outward in the 

 shape of a horn. They are each about 20 millim. in length, 

 and at the base 2 millim. in diameter, gradually diminishing in 

 thickness to the apex, which is obtuse. 



The color of these organs and of the pouch is pale yellow, 

 and the former are clothed with long (3 millim.) fine, sparsely 

 scattered hair. Their distention is accomplished by the muscu- 

 lar contraction of the walls of an internal sac with which they 

 communicate, and which forces into them a yellow, strongly 

 scented fluid. They have no external outlet, nor is this fluid 

 secreted through the pores of the pouch ; its only function in 

 connection with them seems to be to fill and expand them. 



Although I have examined a large number of living speci- 

 mens, only one gave me the opportunity of watching the vol- 

 untary protrusion of this appendage. The operation was 

 interesting. The abdomen was slightly contracted, opening 

 the orifice of the pouch, from which projected two tufts of 

 black fine hair ; as the fluid forced its way out, the hairs, com- 

 mencing at the base, separated and stood erect ; the empty 

 skin, bearing the constantly diminishing tuft, was quickly 



