2/0 CRUSTACEA, ECHINODERMS, ETC. 



curved thorns. Inachus Dorsettensis, Achceus cranchii, 

 and Stenorynchus phalangium are still better entitled 

 to the name of " spider " crabs, on account of their 

 small bodies and extremely long legs. 



Fig. 20 1 



The Spider Crab (Hyas amneus). 



In addition to the above, the interesting group of 

 "swimming crabs" has been introduced into the Crystal 

 Palace and other aquaria, where at least half-a-dozen 

 species are to be seen. The principal general are 

 Polybius, Portunus, and Portumnus. Their adaptation 

 to swimming habits is at once evident on seeing their 

 flattened, oar-like hind legs. When swimming they 

 usually take to the mid-water. The " masked crab " 

 is to be found in some of our public acquaria, and is 

 undoubtedly one of the most attractive. The male and 

 female differ so much in general appearance that they 



