occurrence on the following 4 species of this genus has been proved E. 

 ptjgmcea, serrata, and microplith alma. I have, moreover, found it on Parcrythrops 

 obcsa, and in a single case also on Jfy*idop*ix (lldi'lphij*. I have carefully compared 

 specimens from all these different hosts, and have convinced myself that they all 

 belong to one and the same species. The mode of affixion of the parasite is rather 

 peculiar. As shown by the figure at the bottom of PI. 96, it covers the 

 dorsal face of the carapace of its host like a mantle, invariably turning its head 

 backwards in relation to its host. The exact place where it attaches itself was 

 not formerly sufficiently determined by me, but I am now fully able to 

 confirm the statements of MM. Giard and Bonnier on this point. It is, in- 

 deed, the posterior incurved edge of the carapace, which exhibits the point of 

 affixion for the parasite, not, as formerly supposed, the dorsal face of the last 

 free segment of the mesosome. In one case only have I found it attached^ in a 

 very different manner, viz., to the left peduncle of the superior antennrc in a 

 specimen of il///*/r7o/W,s > didelphys. The male, as above stated, is found within 

 the ventral hollow of the caudal part of the female, and is generally curled up 

 almost in a circle, always clinging to the above-mentioned fleshy cord issuing 

 from the genital region of the female. 



Out of Norway, this form has not yet been recorded, for the specimen 

 examined by MM. Giard and Bonnier was found on an Enjthrops microptlialma 

 taken off the Norwegian coast by the Rev. A. M. Norman. 



Fam. 3. Cryptoniscidae. 



Characters. Body of adult female reduced to a simple sac filled with 

 ova, though sometimes exhibiting slight traces of segmentation, but without any 

 true limbs. Last larval stage resembling in its outward appearance that of the 

 Bopyridce and Dajidce. Antennulse with 2 flagella, and having the basal joint 

 lamellarly expanded behind, the expansion being more generally divided 

 into coarse teeth. Antennal flagellum 5-articulate. Oral cone simple, without 

 any sucking disc. Coxal plates generally closely pectinate. The 2 first pairs 

 of legs subequal, and much shorter and thicker than the others, which, as 

 a rule, are very slender, with long setiform dactyli. Pleopoda with both 

 rami well developed. Uropoda with the outer ramus, as a rule, much 



