igoS.] 



R. E. lyivOYD : Bathynomus giganteus. 



97 



Of equal importance is the fact that among Isopods, the Cirolanidse alone show 

 similar rudimentary oöstegites on the maxilliped (22). Bouvier and Hansen (23) have 

 shown in how many other ways Bathynomus resembles the Cirolanidse. 



The maxilliped of the mature female further differs in possessing a curious process 

 arising from the inner side of its basal joint. This process, which is 7 mm. in length, 

 is composed of soft cuticle fringed with hairs. A rudiment of such a process can be 

 seen in the immature female but not in the male. 



Fig. S- 



Pig. 6. 



Fig. 7. 



Fig. 8. 



Fig. 5. — The oösotegite of the ist thoracic leg (right) viewed from behind, showing the curved 

 appendage. 



Fig. 6. — Right maxilliped of an immature female. 



Fig. 7. — Left maxilliped of a mature female: en. = endopodite ; ex. = exopodite ; i, 2, 3 = the 

 three basal plates ; 00. - the oöstegite. 



Fig. 8. — The subskeletal portion of the cephalic nervous system, x 6. The thick dotted lines 

 indicate the position of the superimposed skeletal plate. The groups of dots represent nerve cells. The 

 largest pair of ganglia at the lowest part of the figure is the ist thoracic ganglion (erroneously lettered 

 s.o.g. in plate xi). 



The thoracic sternites of the mature female differ remarkably from those of the 

 immature female and of the mature and immature males. In the thoracic region of 

 the latter the skeletal sternites are not continuous across the middle line. An examina- 

 tion of the thorax of an immature female or any male shows that there are in each 



