THE MISCHIEVOUS GRIBBMI 367 



that tlie mandibles have no ' palp ' or only a one-jointed 

 one. By the antennal joints projecting in front, the 

 Tiropods extended behind, and the large side-plates of the 

 peraeon radiating laterally and distally widened, the head, 

 the back of the perseon, and the pleon are completely en- 

 closed, and the outline becomes an unbroken oval. The 

 animal, being only one-fifth of an inch long, might, like the 

 still smaller Ga/mpecopeahirsitta, seem to be no fit subject for 

 protective mimicry. It must be supposed that, minute as 

 they are, they are found worth eating by creatures highly 

 enough organised to be guided in their attacks by form 

 and colour. 



Family 6. — Limnoriidce. 



The body is sub-depressed ; the pleon has six distinct 

 segments. The eyes are lateral, wide apart ; the antennae 

 of both pairs are short, the first having a single-jointed 

 flagellum ; the mandibles have a chisel-like cutting edge, 

 the molar tubercle obsolete, the ' palp ' small, three- (or 

 perhaps sometimes two-) jointed ; the first maxillae have 

 two slender plates, the second have three ; in the maxilli- 

 peds the second joint is produced, the five joints of the 

 'palp' are short, its three middle ones somewhat expanded; 

 the epipod is elongate ; all the limbs of the peraeon are 

 similar, not prehensile, but with bifid fingers; the five 

 pairs of branchial pleopods are sheltered in the vaulted 

 pleon, all ciliated except the fifth pair, which is smaller 

 than the rest ; the second pair in the male have the usual 

 stilets; the uropods have two single-jointed branches, 

 both movable, the outer much shorter than the inner. 



Limnoria, Leach, 1814, is the only genus. The type, 

 Limnoria ligTiorum (J. Rathke, 1799), known at Plymouth 

 as the Gribble, has an evil fame for gnawing submerged 

 timber. It is widely distributed. Inaccuracies in the 

 earlier descriptions of the species have been pointed out by 

 the late Mr. Oscar Harger with his accustomed care and 

 acuteness. In New Zealand Mr. C. Chilton has found a 

 second Bpecies, Limnoria segnis, on the roots of the sea- 



