1886.] MR. R. COLLETT ON B AL.ENOPTERA. BOREALIS. 257 



Fig. B. 



Fis. C. 



Fig. D. 



Balcenopterus tmii-etus. 



Fig. A. Female (nat. size 3-5 iiiui.). 



B. Abdominal segment of female, seen fi-om above. 



C, D. Naupliua of female, second stage (nat. size 025 mm.). 



