REPORT ON THE ISOPODA. 



161 



continental zone. Only six species are common to the continental and abyssal zone; these 

 are — 



Nannoniscus bicuspis, 191-1163 fathoms. 

 Eurycope gigantea, 260-658 fathoms. 

 Cryptocope voringii, 350-778 fathoms. 

 Astacilla granulata, 290-620 fathoms. 

 Serolis antarctica, 400-1600 fathoms. 

 Serolis bromleyana, 410-1975 fathoms. 



The Isopod fauna of the abyssal regions may therefore be said to be fairly distinct 

 from that of the shallower waters, since it includes nine distinct genera besides a 

 number of others which are characteristic, and since only seven species out of a total of 

 forty- two ascend into less depths. Of the nine peculiar genera, two, viz., Bathynomus 

 and Anuropus, are certainly to be regarded as the types of subfamilies. 



The continental region, including depths of 100 to 500 fathoms, includes the following 

 genera : — 



Munnopsis.*i 



Eurycope.*f 



Hyarachna* 



Desmosoma* 



Arcticrus.*f 



Astacilla.*^ 



Anceus.*\ 



Serolis. *t 



Janira.*\ 



Jeeropsis* 



Munna* 



Nannoniscus. t 



Pleurogonium. # 



Ischnosoma.*f 



Macrostylis* 



Synidothea* 



Acturides* 



Paranthura.*f 



JEga* 



Apseudes* 



1 TyphlapseudesA 



2 Astrurus. 

 Neasellus. 

 Paratanais* 

 Typhlotanais. *t 

 Tanais* 

 Leptognathia. * 

 Cymodocea* 



3 Acanthoniscus. 

 Cryptocope.*^ 



There are only three peculiar genera, the remaining twenty-seven being found in 

 shallower water, and in the abyssal region ; the asterisk (*) indicates those that are also 

 found in shallow water, the dagger (t) those that extend their range into the abyssal zone ; 

 fourteen range into both these regions, one genus, Nannoniscus, is only found in deeper 

 water, while the remaining eleven range only into the shallower depths. 



I cannot pretend to give anything like a complete list of the shallow-water genera, 



(ZOOL. CHALL. EXP. — PART XLVIII. — 1S86.) 



Ebb 21 



