154 



The mandibles are strong, and always without palps. The anterior maxilla? are 

 normal, with 2 masticatory lobes, the inner of which carries on the tip 2 or 3 

 brush-like setse. The posterior maxillae, on the other hand, exhibit a rather dif- 

 ferent appearance from those in most other Isopoda, being laminar, with only a 

 very slight indication of a subdivision into lobes. The maxillipeds do not completely 

 cover the other oral parts, and they have the terminal part more or less reduced. 

 The marsupial pouch in the female is composed of 4 pairs of broad lamella? is- 

 suing from the bases of the 2nd to 5th pairs of legs. The appendages of the 

 metasome are 6 pairs, the 5 anterior of which are respiratory in character, 

 the inner plate being of a very delicate spongy structure, whereas the outer is 

 more strongly chitinized and covers the inner like an operculum. In some cases 

 this opercular plate contains on the 2 anterior pairs, more rarely on all the 

 pairs, air-cavities or pseudo-tracheae. In the male, the inner plate of the 2nd, 

 and often also of the 1st pair, is peculiarly modified, to serve for copulative 

 purposes. The last pair of appendages represent the uropoda. They are, as a 

 rule, biramose, with the rami uniarticulate, and they project more or less behind. 



The forms belonging to this tribe are generally found in damp situations, 

 beneath leaves, stones or timber, often in great numbers, and feeding, it would seem, 

 on both animal and vegetable matter. They all seem to avoid the full light 

 of day, and some forms even lead a true subterranean existence, in which 

 case the eyes are often found to be rudimentary or wholly absent. As to the 

 respiration, it cannot properly be said to be an exclusive air-breathing in the same 

 sense as in insects. It is in fact to some extent branchial, and therefore a certain 

 amount of atmospheric moisture is indispensable to their existence. It is for this 

 reason, that in very dry weather these animals seem almost wholly to disappear, 

 retiring more or less deeply into crevices and hollows, where some moisture still 

 remains. 



The tribe has been divided into 2 sections, viz., the Ligice and the 

 Onisci. Both of these sections may conveniently be subdivided into several 

 families. Of such families 4 are represented in the fauna of Norway, and will 

 be treated of below. 



Among the several authors, who have made the present tribe their 

 special study, must he named the Danish zoologist, Mr. Budde-Lund, who in his 

 admirable work, "Crustacea isopoda terrestria", has treated of all species at that 

 time known, both indigenous and foreign, amouriting in all to several hundreds. 

 It is to be regretted that this valuable work is accompanied by no figures. 



