42 THE VOYAGE OF E.M.S. CHALLENGER. 



diameter is aboul 0*55 nun., its smallest 0'15 mm. 1 calculated that for ScalpeHwm 

 regium the surface of the lumen of the oviduct was about 0*09 square millimetres, whereas 

 a section of one of the nearlyripe ovarian eggs was not less than 0"28 square millimetres. 

 Therefore, it is either necessary thai the walls of the oviducts be very da-tic, or that the 

 ewes pass through the oviduct when it is much distended. Perhaps both circumstances 

 favour the passage of the ova. 



The number of eggs laid by Lepas is immensely larger than by Scalpellum. In 

 some of the species of the latter genus it is not even a hundred ; in Lepas anatifera it 

 amounts, on the contrary, to many thousands and tens of thousands. In accordance 

 therewith, the eggs of Lepas are very small ; I measured eggs from an egg mass of this 

 species, and their length was only 0"24 mm. The cceca which form the ovary are very 

 narrow and elongate, and contain rows of numerous and relatively small eggs. The 

 ovarian ess when ripe is not so elongate as after its fecundation ; I measured eggs in the 

 oviduct, the length of which was only 014, their breadth being Od mm. The nuclei of 

 the eses in the ovary are again nearh circular, and Lave a diameter of about 0"02 mm.; 



DO •* * 



they may be seen as a rule in the centre of each ovarian egg, and contain a single very 

 distinct nucleolus. In the cceca of younger specimens of this genus, the groups of 

 ovio-erms can be very distinctly made out. The number of ovigerms composing such a 

 group in this genus, however, is much larger than in the genus Scalpellum; their dimen- 

 sions do not show any considerable difference. 



In Conchoderma virgatum the form of the cceca corresponds to that in Lepas. The 



i s are numerous and small. I do not think it of much use to give any details as to 



their dimensions. 



When comparing young ovarian cceca, such as are observed in the peduncles of younger 

 specimens, with those which are gorged with numerous and larger eggs, one feels 

 convinced that a considerable increase in bulk has taken place. This can only have been 

 brought about by a regular and abundant supply of food. Yet it is not so very easy to 

 understand in what way the nourishmenl ofthe peduncle is Wrought about. The only way 

 is, of course, that the Mood — or the fluid which in Cirripedia acts as blood — passes through 

 the narrow band which in the pedunculated Cirripedia runs from the capitulum to the 

 peduncle, at the rostral side near the place where the two scuta meet with their occlu- 

 dent margins. The two strong peduncular (antennal) nerves and the oviducts pass 

 through this narrow commissure; bul so does also a rather wide cylindrical tube which 

 has no distinct wall of its own, and therefore is lined only by connective tissue, and 

 which here represents the body cavity. In those cases in which I found the ovarian e 

 ripe or nearly ripe, I always found tin- canal totally filled up by a delicately granulated 

 mass, which much resembled blend plasma. I therefore think it highly probable that by 

 means of this elongate canal a regular nourishmenl of the pedum le and the organs placed 

 in it is carried on. In Scalpellum parallelogramma I have been successful in tracing 



