THE CANADIAN ENTOMOLOGIST. 197 



period in comparison with that of the other two, and with those elapsing 



between the other instars. The full life-history of each of the bred 



individuals is as follows : 



No. I. No. 2. No. 3. 



Ova deposited May 20 June 5 August 19 



Emergence " 31 " 16 " 26 



I St Ecdy?is June it "24 September 2 



2nd " *' iS "29 " 10 



3rd " "25 July 4 '' T7 



4th '• July I "9 " 24 



5th " " 12 " 20 October 12 



The above gives periods for the full development from occlusion of 



the ova to the adult of 53, 45 and 54 days, the one whose development 



occurred in midsummer having the shortest period. One of the adults 



survived in my aquarium till early January. It was sluggish, but finally 

 died as a result, doubtless, of the abnormal conditions under which it 

 laboured. 



A most noteworthy fact in the development of Belostoma fiiimiiica is 

 the progressive diminution in size of the claw on the anterior tarsi, which 

 finally disappears at the last motilt. In the genus Amorgius this is not the 

 case — the nymphs have two equal-sized claws on the anterior tarsi, long 

 and well-developed, one of which disappears at the last moult. This may 

 be seen in the nymphs of Amorgius annidipes, A. obscuriim and A- 

 americamim. On the other hand, the nymph of B. Boscii is single-clawed 

 in the anterior tarsi in the third to fifth stages, which peculiarity it shares 

 with Abediis breviceps. 



This paper treats only of the more obvious structural differences in 

 the nymphal instars, because lack of material as well as of time to devote 

 to entomology, has prevented the deep study necessary to satisfactorily 

 elucidate many obscure points. What is set down is the result of personal 

 observations, the life and habits have been carefully studied from the 

 living bug, and the anatomical features have been investigated by 

 dissections and microscopical examinations. 



In conclusion, I may say that Belostoma flum'niea is so common a 

 bug, and so easily kept in captivity, that it is possible for any one to breed 

 them and check my results, which I sincerely trust may be done before 

 long. 



