40 
Guide to Crustacea. 
Table-case shown being perhaps larger than the average, but in Arctic seas, 
No - where they are especially abundant, they often attain a much 
greater size, as is shown by the specimen of Diastylis goodsiri 
(Fig. 20) from the Kara Sea. 
Diastylis goodsiri , female, from the side, enlarged, a.', antennnle ; Z. 1 -?. 5 , the 
five pairs of walking-legs; m., brood-ponch ; ps., “ pseudo-rostrum,” 
formed by lateral plates of the carapace ; t.. telson ; ur., nropods. (From 
Lankester’s “ Treatise on Zoology,” after Sars.) 
Order 3. — Tanaidacea. 
Table- case Six of the thoracic somites are always distinct, the reduced 
■ No ' 6 ' carapace involving only the first and second (Fig. 21). On each 
side the overhanging carapace encloses a cavity within which lies 
ex. 
a 
Fig. 21. 
Apseudes spinosus, female, from the side, enlarged, ex., vestiges of exopodites 
on second and third thoracic limbs ; oc., the small and immovable eye- 
stalks ; sc., scale or exopodite of antenna ; ur., nropod. (From Lankester’s 
“Treatise on Zoology,” after Sars.) 
(as in the Cumacea) a branchial appendage attached to the first 
thoracic limb. The second thoracic limb is chelate or pincer-like, 
and the second and third may carry minute vestiges of swimming- 
branches (exopodites) (Fig. 21, ex.). The eyes, when present, are 
set on small and immovable stalks (Fig. 21, oc.). 
