xl INTRODUCTION. 
it generaily hes pendant from the inner side of the coxa, 
and is longer in some species than in others. In the 
genera Proto and Caprella, the penis seems to be 
formed out of the anterior pairs of pleopoda, just as 
is the case in the Brachyura, among the Stalk-eyed 
Crustacea. These observations are further confirmed by 
those of M. Rousel de Vauzeme on the genus Cyamus. 
In the Jsopoda, these organs have been carefully worked 
out by Siebold, Lereboullet, and Schdbl. In the genus 
Ligia (Fig. 16), we have observed on each side three testes, 
| consisting of long narrow 
vesicles, thinning away to 
exquisitely fine filamen- 
tary prolongations. These 
vesicles increase in dia- 
meter as they approach 
towards the efferent duct, 
where they rapidly be- 
come constricted before 
uniting with the vas defe- 
rens. These vesicles are 
filled with seminal cells, 
and are, we believe, the 
true testes. M. Lere- 
boullet, however, in his 
researches on the Onis- 
cide,* states that he has 
observed that each of 
Fic. 16. these fusiform sacs has 






attached to its extremity other irregular sacs, which 
he regards as the principal secreting organs, and con- 
sequently the spermogenic glands or testicles. These 
* Mém. sur les Crustacés de la Famile des Cloportides, par A. Lereboullet. 
Strasburgh, 1852. 
=<. 
