PLATE XIII 



Development of the gonads in Sagitta gazellae Small Northern race. 



Fig. i. Late stage II, showing the opaque tail segment characteristic of 

 the stage, rudimentary seminal vesicles and short thin ovaries. 



Fig. 2. Stage II/III, a rare intermediate stage, the seminal vesicles are 

 full sized but the tail segment is still opaque, the ovaries are still 

 short and thin. 



Fig. 3. Late stage III, the tail segment is empty and the seminal 

 vesicles full, the ovaries are somewhat thickened. 



Fig. 4. Late stage IV, the seminal vesicles have burst, and the ovaries 

 are nearly fully developed. 



