ORDER PODOSOMATA. 149 



In the former of these families the legs are as short 

 as the body, and robust, and the antennae and palpi are 

 obsolete. They are parasitic upon the whale, the type, 

 Pycnogonum balcenarum (pi. 1), being about three quarters of 

 an inch long. Both in respect to their general appearance 

 and habits this genus is very analogous to that of Cyamus 

 (amongst the Isemodipodous Crustacea). 



In the latter family the body is small and linear, the legs 

 very long, with a pair of antennal claws, and two palpi. 

 These are extraordinary marine animals, resembling spiders, 

 but having only four pairs of legs : they are found amongst 

 various aquatic plants, under stones, &c. They appear to 

 be destitute of any appearance of breathing pores, whence 

 Latreille's name Aporobranchia. The females are furnished 

 with an additional pair of short filamentous processes, to 

 which the eggs are attached. There are several British spe- 

 cies described by Dr. Johnston in the Magazine of Zoology 

 and Botany. Dr. Leach has figured two species, N. gracile 

 and femoratum, in the Zoological Miscellany. 



o3 



