Prof. R. Kossmann on the Cryptoniscidaj. lo 



enough, remain alive, and arc made use of by the Zeuxo. 

 The head of the latter, which is finally inserted deeply into 

 the body of the crab, although always still in a great lacuna 

 of the radiciform pedicle of the Sacculina, presents, besides 

 the buccal aperture, only four cylindrical processes, of which 

 one pair is usually longer than the other. By their form and 

 position they give rise to the supposition that they are the 

 antennge of the larva which have lost their articulations. They 

 evidently effect the fixation of the animal. In some species 

 the fore part of the body, from the place where it enters into 

 the body of the host to the mouth, is drawn out into a long 

 peduncle ; in others it is rather short. 



Upon another parasitic Cirripede {Peltogaster) lives the 

 genus Cryj)t07tiscus^ F. Miiller, under exactly similar vital 

 conditions. Its head docs not form a peduncle, but within 

 the aperture which it has perforated we find four pad-like 

 swellings surrounding the mouth, which, from analogy, we 

 may also regard as modified antennaj. That this genus 

 almost always brings about the destruction of the Peltogaster 

 itself has been already indicated by Fritz Miiller and con- 

 firmed byFraisse; now and then, indeed, we find a specimen 

 which seems not to be seated directly upon the hermit-crab, 

 but has bored somewhere into the mantle of the Peltogaster ] 

 but if such stray examples, on the one hand, do not quite 

 cause the destruction of the Peltogaster ^ on the other hand 

 they do not seem themselves to arrive at female sexual 

 maturity. 



It is otherwise with the genus Liriopsis^ Max Schultze 

 {Liri'ope, Rathke), which also lives upon a Peltogaster. 

 This animal (the anterior and posterior ends of which have 

 been hitherto mistaken) does not perforate the pedicle of the 

 Peltogaster, but slips into the cavity of its mantle, and per- 

 forates the mantle from within. Thus the anterior half of 

 the body is inserted into the blood-lacunas of the mantle, 

 while the posterior half lies free in the mantle-cavity, and 

 the perforation which the parasite has made causes a median 

 constriction of the animal. But in this case, not only the 

 head, but at least five segments of the middle-body are 

 inserted into the host ; and as the aperture through which 

 the brood of the Liinope swarms out is formed upon these seg- 

 ments; the parasite, when the brood is mature, or perhaps a 

 little earlier, must also break through the outer wall of the 

 mantle. This is probably effected less by boring than because 

 its own growth exerts such a pressure upon the tissues before 

 it that the latter become atrophied and finally burst. The 

 parasite then remains with the abdomen in the mantle-cavity 



