REPRODUCTIVE SYSTEM. 101 



likewise extend up between the two layers of corium round 

 the walls of the shell, and chiefly in the interspaces be- 

 tween the depressor muscles of the opercular valves. In 

 Chelonobia, they enter between the radiating septa in the 

 thickness of the walls : in Coronula diadema, they extend 

 from over the basal membrane into the six large square 

 chambers (PL 16, fig. 7, v) separating the radii and alae : in 

 Tubicinella they are confined to the basis : in Xenobalanus, 

 they form a layer over the basis and likewise round the upper 

 part of the peduncle-like body, which answers to the shell of 

 other sessile cirripedes. 



As after the most careful and repeated examinations of 

 various Lepadidae, I was convinced that there were no ovi- 

 ducts, so I have come to a similar conclusion in regard to 

 the Balanidae ; the ova being brought to the surface, by the 

 formation of a new membrane round the sack underneath 

 them, and by the subsequent exuviation of the old mem- 

 brane. The ova are united together by a most delicate 

 tunic investing each egg ; the ovigerous lamellae being thus 

 formed, as in the Lepadidae. In the cases of Chthamalus 

 stellatus, Balanus balanoides, and Platylepas decorafa, I saw 

 a pair of very distinct but fragile lamella 3 . In Xenobalanus, 

 the two ovigerous lamellae form two sub-cylindrical packets, 

 pointed at their lower ends and often cohering. There are 

 no ovigerous fraena, for the attachment of the lamellae ; the 

 ova being sufficiently well retained, as it would appear, by 

 the well-closed shell. I have elsewhere stated my full belief 

 that it is the ovigerous fraena which have been metamor- 

 phosed into the branchiae of the Balanidae. Most sessile 

 cirripedes breed when very young; and I have every reason 

 to believe that they breed several times in the year. The 

 ova are ovate, and vary in length from sjggth of an inch in 

 Chthamalus, to <^yh in some species of Balanus, in which 

 this greater length was owing to a more elongated shape, 

 — up to gllsth in some other species of Balanus. The ova 

 are wonderfully numerous, especially in the genus Coronula. 



I may here mention the singular case of some elongated 

 specimens of Balanus balanoides, from Tenby, in South 

 Wales: some of these presented nothing abnormal; but in 

 no less than seven specimens, the two, three, or four poste- 



