FEATS OF BROIL AND BATTLE 275 



An undoubted weapon of defence is the bayonet 

 telson of Glyphocrangon (Fig. 52). In this animal, 

 as in Plastocrangon (Fig. 56), the telson and the 

 two abdominal segments immediately in front of it, 

 interarticulate by means of singularly-perfect movable 

 dovetail joints, which, while permitting the freest 

 movement of all three segments, enables them at 

 any moment to be firmly locked together in such a 

 way that an enemy is liable to transfix itself on the 

 dagger-like telson. Another example of the armoury 

 of the deep is the acute, serrated, antennal scale of 

 Hoplophorus, which also has a sort of locking joint. 



Among the temperate-zone Crustacea found in 

 the depths, but not in shallow water, in Indian lati- 

 tudes, the Lithodea are worthy of mention. These 

 singular crustaceans are hermit-crabs in all their 

 organisation, and yet they have a superficial resem- 

 blance to crabs which is quite misleading ; but a 

 certain tendency to lopsidedness, as well as the 

 presence of an antennal scale and the curious position 

 of the almost rudimentary last pair of thoracic legs, 

 which are carried inside the branchial chamber, at 

 once bewray them. 



Another genus of the temperate zones which is 

 represented in the cool depths of Indian latitudes, is 

 the small frog-crab Lyreidus. One species, Lyreidtts 

 channeri (Fig. 69), is very often dredged in 200-400 

 fathoms off the coasts of India and Ceylon. Uncrab- 



