3.C0 BRITISH ENTOMOSTRACA. 



of theii" existence they fasten themselves upon their prey 

 is at present unknown ; but no sooner apparently does 

 this happen than the eye clisai)i)ears, and the feet either 

 disappear also, or are transformed into other organs. In 

 some they are changed into foot -jaws, by means of which 

 they fix themselves u}»o!i the body of the fish they select 

 for then- habitation. In others they are transformed into 

 long and strong prolongations like arms, which unite 

 together either at the tips only, or from the roots all the 

 way up to the point, where they send forth a short horny 

 stem, that v.idens into the shape of a round button, and 

 which, when buried in the skin or tlesh of the tish, forms 

 such a strong attachment, that the Lerneadae cannot be 

 detached without being torn, or by being carefully dis- 

 sected out. j\Iost probably the species in which this 

 development takes place first fasten themselves to their 

 foster-mother by the foot-jaws, as the first-mentioned set 

 do, and after being buried in the flesh, these organs 

 assume this peculiar formation, otherwise it is difficult to 

 conceive how such an instrument coidd penetrate deeply 

 into the body of the lish. A third mode of transforma- 

 tion of the feet appears to be into a series of horny 

 branchlets developed round the mouth, and which, when 

 they have penetrated deeply into the soft parts of their 

 host, serve eflectually to retain the parasite in its place. 

 The adult Lerneadae show, with the exception of taking 

 food and lavinsj eo-os, very few and feeble sio;ns of life, 

 whether attached to the nourishing animal or when sepa- 

 rated from it. jMany of the genera show no external 

 signs of life at all aftei- separation from their foster-mother; 

 others move their jaws for a short period, or their head 

 may be seen to move leisurely in dift'erent directions for a 

 little time and then cease. In one species [L. bra/ichialis), 

 Kroyer tells us, that he observed a singular phenomenon 

 that nobody else had before noticed. When he touched 

 an individual, it squirted, he says, " from the vent, a 

 transpai'eut stream of fluid to the distance of a foot and 

 a half, and this it repeated several times one after 

 another." 



