46 Dr. F. Miiller on the Rhizoeephala, 



only for the respiration of the eggs, which must pretty com- 

 pletely stop its access to the body of the mother. In many 

 other Crustacea, also, the attachment of the eggs to the body of 

 the mother may be necessary for the development of the brood, 

 less on account of the protection thus afforded them than on 

 that of the constant change of water ; even nearly mature eggs 

 of Crabs and Prawns separated by me from the body of the 

 mother have always come to nothing, whilst the females kept in 

 confinement have hatched with certainty. 



In the anterior sinus of the disk is an arched chitinous shield 

 (fig. 2 s) with concentric strise, between which brownish-coloured 

 particles are usually deposited. From its middle there springs 

 a short neck, which pierces through the skin of the Porcellana. 

 Within, it is surrounded by a strong chitinous ring, 0*2 to 0*3 

 mill, in diameter, which is continued into a serrated crown, di- 

 lated above, possessing a golden lustre. This crown is variously 

 developed according to the age of the animal (k, figs. 2, 3). It 

 is produced by the chitinization of the skin of the head. Single 

 small chitinous lamellae (fig. 3, b) are met with sometimes above 

 the crown, beyond which the soft skin of the head extends but 

 little. From the upper surface of the head, on which I found 

 no trace of mouth, eyes, or antenna?, there issue numerous tubes 

 (fig. 3, w), as much as 0*15 mill, in diameter, part of which, 

 especially the outer ones, terminate csecally at a very short di- 

 stance, whilst the others, ramifying repeatedly, advance towards 

 the intestine of the Porcellana, embrace this for a long distance, 

 even into the thorax, and at last terminate in blind loops. 

 Not unfrequently cords, more than 0*5 mill, in thickness, formed 

 by the twining together of numerous separate tubes, are seen 

 taking their course towards the intestine of the Porcellana. 

 These roots, as they may be called from both their appearance 

 and function, contain, in their delicate membrane, numerous 

 fat-globules, which are distinguishable, by their much smaller 

 and at the same time uniform size, from the fatty particles in 

 the tail of the Crab. 



That the roots are united through the neck with the large 

 receptacle of fluid beneath the ovary is proved very simply and 

 certainly by a circumstance which I was unable to explain before 

 their discovery : — When the head of the parasite is removed from 

 the body of its host, and sometimes even when the tail of the 

 Porcellana is torn away from the thorax, an instantaneous and 

 very striking pallescence of the Lernaodiscus takes place in con- 

 sequence of the evacuation of the reddish fluid. Wliether the 

 cavity for the nutritive fluid, which can hardly be called the 

 digestive cavity, commencing in blind roots, also terminates 

 csecally, I must still leave undecided, although a narrow process 



