1010 A REVISION OF THE AUSTRALIAN ISOPODA, 



hroad, and bears a plate-like appendage, which is armed inter- 

 nally with a row of four or five chitinous teeth, and distally 

 with some short setee ; the following three joints are expanded, 

 especially the fourth and fifth ; the two terminal joints are 

 narrower. The six posterior pairs of pereiopods each termi- 

 nate in two claws, with a third claw or spine a little further 

 back on the A^entral border of the propodos ; the third and 

 fourth joints are each produced into a process tipped with one or 

 two veiy long setae. The ventral surface of the last segment of the 

 abdomen frequently possesses an acute spine in the middle line 

 behind, but this is sometimes rudimentary. The abdomen 

 possesses three pairs of appendages besides the terminal iiropoda. 

 Of these the first pair are biramous, the exopodite being large and 

 crustaceous, meeting with its fellow in the middle, and completely 

 covering the posterior appendages ; it is divided into two parts by 

 an oblique articulation ; its endopodite is much smaller and more 

 delicate, tipped with a few setae, and is placed behind the 

 expodite. The second and third pairs of abdominal appendages 

 are likewise delicate ; the second is biramous, the third 

 uniramous. The bases of the first pair of abdominal appendages 

 are covered in both cases by a broad plate, with a bifid apex 

 attached to the posterior border of the last thoracic segment. The 

 eggs are borne in a bi'ood pouch on the ventral surface of the first 

 four segments of the pereion. 



The specimens which I have at my command at present are not 

 sufficiently well preserved to enable me to ascertain the position 

 of the embryo in the egg, but I have little doubt on a careful re- 

 examination of the subject that the present form (in spite of the 

 direction of the four anterior pairs of thoracic appendages) finds 

 its nearest allies among the Asellidce, not among the " Ahnor- 

 malia," as I was at first inclined to suppose. The grouping 

 together in Dana's classification under the title of Anispoda, of a 

 number of forms whose chief bond of connection is the direction 

 of the thoracic appendages results an an extremely artificial 

 arrangement. 



