CIRRIPEDIA. 



15 



branching tubes with a long intromittent organ arising below the vent, at the base of 

 the sixth pari- of feet. The ovaries are situated in the peduncle, and superficially 

 resemble the spermogenous organs. The eggs when ripe pass out into the capitulum 

 and there are impregnated. Leaving the egg for the present we will consider a highly 

 interesting subject connected with the reproduction of these animals. 



As has been said, the greater portion of the barnacles are hermaphroditic, that is, 

 in each individual are combined the organs pf both sexes. Now, one would think that 

 these animals were peculiarly adapted for self-fertilization, but this, so far as our 

 knowledge goes, is not the case. Large numbers of plants have both stamens and 

 pistil (male and female organs) existing in the same flower, and in the older botanical 



works, especially those with a teleological ten- 

 dency, attention was called to the adaptations 

 which these flowers exhibited for fertilizing 

 themselves. But subsequent observations 

 show that another interpretation can be placed 

 upon the structure of these organs, and to-day 

 it is clearly proved that in many plants self- 

 fertilization is impossible, and that pollen of 

 another flower is absolutely necessary for the 



m^ 





4 



/ 



Fig. 18. — Scalpellvm regium, with complemeutal 

 males attached at a. 



Fig. 19. — Complemental male of Scalpellvm regium, 

 greatly enlarged. 



fertilization of the ovule and the development of the seed. So with the barnacles. When 

 we study more closely their habits, their anatomy, and the relations of the individuals to 

 each other, we see that there exists a striking adaptation for cross-fertilization. In Lepas 

 fascicularis, as in the majority of the barnacles, the individuals occur in colonies placed 

 in close juxtaposition to each other, and so the moderate-sized intromittent organ can 

 be inserted into the shell of the adjoining specimen. In Acasta, a form which is found on 

 certain corals, the different individuals are usually a little distant from each other, and 

 here we find the intromittent organ extremely elongated, several times the length of 

 the body, so that it can extend from one specimen to its neighbor. Certain barnacles 

 are always found semi-parasitic on larger animals. One species, Anelasma squalicola, 

 makes a sort of burrow in the skin of sharks, and has a seeming provision for cross- 

 fertilization — the animals occur in pairs. There is still a more peculiar condition. The 



