PROCEEDINGS AM. PHILOS. SOC. 



VOL. XLI, No. 168, PLATE XV. 



^^ 







^7 



'.I. ^ 





-5«y «:^^! 



a '-'■ , 



%^^' 



(5-3 



./. 2 



4-f 



»& 





9 



36' 



b'h 



% 



4^ 



NICHOLS-SPERMATOGENESIS OF ONISCUS ASELLUS LINN. 



