XXX MONTHLY PROCEEDINGS 



Dr. Horn called the attention of the members to an instance of 

 dimorphism in the female of Desmocerus aurij^ennis Chev., the occur- 

 rence of which is not common. The male of this species has the 

 elytra of an uniform orange color, the punctuation is coarse on the 

 disc ojradually becoming finer toward the tip. The normal female has 

 the disc of the elytra coarsely punctured but much less so than the 

 male and behind the middle very much finer, the elytra are of the 

 same color except that thei*e is a large discal steel-blue space resem- 

 bling in general outline a keystone, of variable extent. In the second 

 form of female the elytra are bluish-black narrowly bordered at base, 

 sides and apex with the orange color, the surfiice not shining, the 

 punctuation being also much finer and denser than in the normal form. 

 The punctuation of the thorax is also finer and denser. 



Dr. Horn stated that this latter form had been supposed to be a 

 distinct species by some of his European correspondents, but that he 

 was confident that it was merely an instance of dimorphism, which 

 view is at least partially confirmed by Mr. Morrison, who stated that 

 the specimen shown had been taken in copulation with the normal 

 male. 



In answer to inquiry Dr. Horn stated that sexual dimorphism is 

 not uncommonly observed especially in the female sex, citing as 

 examples several species of Dysticus and Ganmdijtes ; in the male 

 true dimorphism is very rare unless we consider the impoverished 

 forms of Prionus imhricornis an instance, or probably better the 

 .almost hornless males of Phanseus and Stratpgua. These Dr. Horn 

 did not consider instances of true dimorphism in the sense in which 

 the female Desmoa-rus is noted, nor in the same category with the , 

 females of Dutiscus with the elytra plain or sulcate. 



The following additions to the Library of the American Entomo- 

 logical Society were announced : — 



Proceedings of the Boston Society of Natural History, vol. xx, 

 pp. 177 — 208. From the Society. 



Bulletin of the Essex Institute, vol. xi, Nos. 4 — 9. From the 

 Institute. 



Canadian Entomologist, vol. xi, Nos. 9 and 10. From the Editor. 



North American Entomologist, vol. i. No. 5. From the Editor. 



Entomologist's Monthly Magazine, Nos. 185 and 186. From the 

 Conductors. 



Proceedings of the Zoological Society of London, 1879, Parts 

 1 and 2. From the Society. 



