CHARACTERISTIC DEEP-SEA TYPES. 
SEA-URCHINS. 95 
to be its normal form and attitude. It is quite dangerous to 
handle these specimens when alive, the wounds they infliet with 
Fig. 359. — Asthenosoma hystrix. 3. 
their numerous minute sharp stinging spines producing a decid- 
edly unpleasant: sensation, accompanied by a slight numbness. 
The sting is fully as painful as that of Physalia. These modern 
Echinothurize were 
subsequently found 
very abundant at 
moderate depths. 
The “ Challenger” 
dredged a gigantie 
species from this 
group, measuring 
no less than 312 
mm. in diameter. 
The spines of the 
lower surface are 
shod with a pecu- 
liar hoof-shaped 
tip; on the test are 
sheathed spines un- 
like those of any 
PA 
NS 
Fig. 360. — Phormosoma placenta. $. 
