272 M. E. Hesse on the Means by which certain Species of 



ccivablc that, if the prevision which presides over the conserva- 

 tion of all existences did not come to the aid of these degraded 

 Crustaceans, they would speedily disappear, or, at least, that an 

 entire family would perish with the fish which served it at once as 

 a prey and a place of shelter. It is, therefore, of great import- 

 ance to prevent such a result. I propose to see whether the 

 facts which I have ascertained may justly be regarded as des- 

 tined to provide against this destruction. 



It is not rare to find female Trebite, Caligi, Pandora, and 

 Chondracanthi to which young Crustacea of the same species 

 are affixed by a cord, which, although it cannot be called umbi- 

 lical, may be denominated, by analogy, the frontal cord. This 

 bond which unites the embryo with its mother does not fulfil 

 functions analogous to those of the umbilical cord in the higher 

 animals, but is destined simply to unite the one to the other. 

 Attached by one of its extremities to the anterior part of the 

 frontal margin of the young Crustacean, it is affixed by the 

 other end to the body of the mother, by means of a circular 

 dilatation in the form of a sucker; and it is sufficiently long 

 and flexible to allow the young Crustacean to act to a certain 

 extent independently of its mother, without disturbing her 

 movements, and to apply itself to the fish upon which they live 

 in common. 



It is a spectacle at once surprising and interesting to see 

 these embryos (especially those attached to the Trebite and Ca- 

 ligi, which swim with tolerable rapidity) following the evolutions 

 of their mother like a little boat towed along by a larger vessel, 

 or, again, as a fish attached to a line which keeps it a prisoner, 

 yields to the traction which is thus exerted upon it. 



What is the purpose of this curious union ? Is it possible to 

 assume it to be the effect of chance, when analogous facts are 

 frequently presented, and have been proved to occur, in several 

 species of these Crustacea ? Can it be supposed that it is for 

 the purpose of the alimentation of the embryo by the mother, 

 when the bond of union does not establish any internal relation 

 between them, and they each obtain their own nourishment ? 

 I think not ; and we must therefore assume that there is some 

 other motive. 



If we assume that this young Crustacean is a male, and that 

 the female, seizing a favourable opportunity, passes, carrying 

 it with her, from the fish on which they were living together, to 

 another, we shall at once perceive the consequences of this 

 transmigration, which, uniting in itself all the elements neces- 

 sary for reproduction, allows this female and the male which 

 accompanies her to found a new colony. This supposition does 

 not appear to me improbable ; for, of two things, one must be 



