62 
Guide to Crustacea. 
Table-case Island, in the Indian Ocean, by Dr. C. W. Andrews, F.R.S., of the 
No. 12. Geological Department of the Museum, and it shows a specimen 
of Birg us in the act of descending the trunk of a sago-palm. 
The members of the family Lithodidae have become completely 
crab-like in shape, and were formerly classified with the Brachyura, 
with which, however, they have no direct affinity. They may he 
at once distinguished from the true Crabs by having only three 
pairs of walking-legs visible behind the chelipeds, the last pair 
being carried folded up within the branchial chambers. Their 
relationship to the Hermit-Crabs is shown by the fact that the 
Fig. 41. 
The “ Northern Stone-Crab,” LitJiocles viaia, much reduced. The last pair of 
legs are folded out of sight in the gill chambers. [Table-case No. 12.] 
abdomen is frequently asymmetrical, and has appendages only on 
one side. The last pair of abdominal appendages (uropods) are 
wanting. 
The “ Northern Stone Crab,” Lithodes maia (Fig. 41), found on 
the more northerly coasts of the British Islands, belongs to this 
family. Cryptolithodes is an allied genus in which the carapace is 
expanded at the sides so as to cover the limbs completely. A 
specimen of the large Echidnocerus cibarius found on the West 
Coast of North America is placed in the lower part of Wall-case 
No. 2. 
