560 lepadidjE. 



on their ventral side. The testis is rounded, and consists 

 of a mass of cells, on an average ^th of an inch in dia- 

 meter. The vesicula seminalis varies extremely in condition, 

 being either a mere rather broad vessel, enlarged where it 

 joins the testis, or a bag fully as large as the testis itself, 

 and distended with spermatozoa, all arranged parallel to its 

 longer axis. There was an evident relation between the size of 

 the vesicula seminalis and that of the testis, the number of the 

 cells in the latter decreasing as the mass of the spermatozoa 

 increased : there was also an evident relation between the 

 age of the male and the state of these organs ; younger and 

 more opaque individuals, having their testes of large size; 

 and older specimens, with the lower end of the peduncle 

 arrived at its full dimensions, having the vesicula distended. 

 Some few old specimens had evidently discharged their 

 spermatozoa. By dissection I more than once distinctly 

 traced the vesicula seminalis entering the broad lower end 

 of the penis. The membrane, forming the vesicula, is 

 ringed, and I presume is, as in other cirripedes, contractile, 

 so as to expel the spermatozoa. The probosciformed penis 

 (m) is of extraordinary length : it is plainly ringed, or rather 

 articulated, in this respect resembling that organ in Ibla and 

 Alepas ; it tapers gradually, and terminates (as usual) with 

 a brush of fine bristles ; it is furnished with delicate volun- 

 tary muscles, arising from the body round its basis, and 

 extending no doubt up to the apex, but too fine to be traced 

 all the way. Its broad lower end is attached in a slight de- 

 pression, on the ventral side of the sack, a little above the point 

 of attachment of the pupal antennas. According to all analogy, 

 the spot whence the penis springs must be considered as re- 

 presenting the thorax and abdomen ; and the outer membrane 

 of the penis is here, as on this view it should be, reflexed and 

 is continuous with that lining the sack. Ordinarily the penis 

 lies coiled up in complicated folds, appearing like a large in- 

 testinal worm, and fills the lobed part of the peduncle, which 

 apparently serves for no other purpose than its reception. In 

 one case in which I dissected out the penis, I found it in 

 its contracted state ^th of an inch in length, equal to that 

 of the entire capitulum and peduncle; in a specimen, in 

 which the penis had been naturally exserted, the part which 



