12 Prof. R. Kossmann on the CryptoniscidfB. 



with deposited ova and thereby enlarges in proportion as the 

 ovaries (and at the same time also the alimentary organ) 

 diminish in volume. 



That the ova obtain the change of water necessary for respi- 

 ration, is provided for by brisk pumping movements, which, 

 as Fraisse correctly describes, are effected in this later stage 

 by the musculature at the two brood-space or respiratory 

 apertures ; and that the current of water sliall not wash out the 

 ova, by a system of villiform valves which close the apertures 

 eelpot fashion, as Fraisse has also shown. This whole ar- 

 rangement is produced, moreover, before the last moult of the 

 animal, and therefore, in a certain stage, the fissure of the 

 brood-chamber still appears, as Fraisse says, " covered and 

 closed by a thin cuticular layer." Subsequently, however, 

 the fissure still holds together, only because the two margins 

 are to a certain extent interlocked ; with a little effort they can 

 be readily forced asunder without tearing anything. But spon- 

 taneously the fissure certainly only opens when the brood- 

 cavity is overfilled, and the parent animal performs the most 

 violent contractions. As Fraisse correctly describes, these 

 often still continue when all the ova are already expelled ; and 

 as, at this time, the ovary and alimentary apparatus, tlie only 

 coloured organs of the animal, are completely retrograded, 

 the animal, which now resembles a torn and perfectly trans- 

 parent rag, and yet contracts violently, presents a very 

 remarkable ajjpearance. 



Passing over many details of less general interest I cannot 

 .abstain from stating something with regard to the mode of 

 taking nourishment and the alimentary organs. 



In Cryptothir [Hemioniscus] ^ as Buchholz has already 

 shown, the cephalon and the pereion as far as the antepenulti- 

 mate segment remain larviform throughout life ; in accord- 

 ance with this the small boring and sucking apparatus, 

 consisting of the labrum and labium, between which two 

 styliform mandibles are placed, serves through life as the 

 organ for the inception of nourishment. This anterior divi- 

 sion of the body is, however, also deformed in the other 

 genera. The genus Zeuxo^ which I discovered in 1872, 

 lives upon parasitic Cirripedes, especially upon Sacculina, a 

 parasite of the Brachyura. It perforates this animal, the 

 pedicle of which ramifies like a root in the body of a common 

 crab, at the point where the pedicle enters into the body of 

 the crab, and draws nourishment from it, after the fashion of 

 a plant ; it consequently intercepts the nourishment of the 

 Sacculina, and often causes it to die away altogether with 

 only the exception of the roots. These roots, singularly 



