The defect of mouth-organs probably does not apply to the period of youth, which some of them spend parasitically in the body-cavity of worms (Giard, 1896).
A curious effect of parasitism, well illustrated in crabs, though not confined to them, has been expounded by Professor Giard, namely, that it tends to obliterate the secondary sexual characters.
(Isopoda), Sars (1896-1899), while their multitude precludes specification of important contributions by Benedict, Bovallius, Chilton, Dohrn, Dollfus, Fraisse, Giard and Bonnier, Harger, Haswell, Kossmann, Miers, M`Murrich, Norman, Harriet Richardson, Ohlin, Studer, G.
Zelinkia and Philosyrtis are two slightly aberrant forms described by Giard from certain diatomaceous sands.
Giard, C. R.
The second family, discussed by Delage, Giard, Kossmann and others, has no dearth of genera and species, though about several of them the information is scanty.
For the complicated parasitism of isopods and Sacculinidae on the same hosts Giard and Bonnier (Bopyriens, 1887, p. 197) should be consulted.