NATURAL HISTORY STUDIES 



molluscan types are abundant ; and finally there is 



a weird army of voracious fishes. 



Fitnesses. A common feature in the fixed Deep- 



Sea animals is the posses- 

 sion of long stalks on 

 which the body is raised 

 high out of the treacher- 

 ous ooze. A similar fit- 

 ness is seen in the ex- 

 traordinarily long limbs 

 which many of the crus- 

 taceans and sea -spiders 

 exhibit. They illustrate 

 an extreme of lankiness 

 and they may be thought 

 of as walking on stilts. In 

 many cases the limbs are 

 several times longer than 

 the body. There can be 

 little doubt that these 

 elongated limbs are suit- 

 able for moving delicately 

 on the soft surface. Some 

 of the Deep-Sea brittle- 

 stars show long arms as 

 compared with shallow 

 water forms. The extra- 

 ordinary elongation of 

 limbs and other parts 

 would be impossible 



except in perfect calm. 



Many Deep-Sea animals are very delicately built, 

 214 



Deep-Sea Brittle Star or 

 Ophiuroid, Astrocharis 

 virgo, showing the dispro- 

 portionate elongation of 

 the arms very liable to 

 breakage and the very 

 small central disc. (After 

 Koehler.) 



