EXPLANATION OF PLATE XVI. 



Life-history of the Gall-fly Neuroterus lenticularis. On the left, the partheno- 

 genetic (spring) generation, (i) Fly with ovipositor withdrawn ; (2) with 

 ovipositor extended; (3) abdomen and ovipositor enlarged; (4) galls from 

 which the parthenogenetic females hatch. On the right, the sexual (sum- 

 mer) generation, known as Spathegaster baccarum. (5) Male; (6) female; 

 (7) abdomen and ovipositor of sexual female enlarged ; (8) galls from 

 which the sexual generation hatch. (The figures of the flies are from 

 drawings by F. BALFOUR BROWNE, Esq.; the galls from specimens in the 

 Cambridge Museum.) (From the Author's Determination of Sex.} 



