PERACARIDA fJfVSWACEA) ANT) EUCARIDA {DECAPODA) 83 



Pagiinis bernhardiis^ Leach. When disturbed on a slope in a 

 rock-pool, this hermit crab rolls to the bottom and simulates an 

 inanimate shell. This species has ten branchiae along the side, 

 a single stunted one, like Carcinus vicenas, on the base of the 

 first pair of foot-jaws. The latter have no branchial whips, so that 

 the gills would appear to be cleaned only by the water which has 

 free access, or the flexible margin of the carapace exercises some 

 influence on them ; and they differ considerably from those of the 

 Brachyura. The mandible, maxillae, and maxillipedes lean to the 

 Macrourus type. The mandible has a hard and sharp cutting edge, 

 and the tip of the well-developed palp curves beneath it on each 

 side and aids in all the functions of the parts. The first maxilla 

 has its protopodite broad and flattened, the inner division of its 

 endopodite narrowed below, broad at the tip, whilst the outer 

 division is a slender process with an avian tip. The second maxilla 

 has its two divisions of the protopodite broader than in Astacus, 

 and both are split at the tip, the posterior more deeply and 

 unequally, whilst the endopodite forms a small pointed process. 

 The exopodite (plus the epipodite of some scaphognathite) is rather 

 short and broad but powerful. The first maxilliped has a long anterior 

 division of the protopodite of a curved ovate-lanceolate shape, the 

 posterior division considerably smaller and irregularly quadrate. 

 The endopodite is a slender rod bent at the base at an obtuse 

 angle. The exopodite is broad at the base, with a projecting 

 rounded external margin, and tapers distally to its articulation with 

 the slender, curved terminal process. The second maxilliped has 

 a stout, limb-like endopodite, and the more slender, cylindrical 

 exopodite is about the same length, with a longer terminal process 

 than in the first, the whole more nearly resembling the organ in 

 C. mcenas. The third maxilliped has its endopodite greatly 

 enlarged and elongated, as in the lobster, so that it is very promi- 

 nent, whilst the cylindrical exopodite is comparatively small and 

 its terminal process slender. 



Corystes cassivelaiaius, Penn. Bell states that "the surface is 

 covered with minute scattered tufts of very short hair, scarcely 

 distinguishable by the naked eye,'' but none of those obtained 

 shows this feature ; thus in a male in which the new carapace was 

 just attaining firmness, the pointed calcareous tubercles alone 

 covered the surface of the carapace, which, at its junction with 

 the abdomen, had a fringe of hairs beneath the thickened rim. 

 The smoother dorsal surface of the abdomen, on the other hand, 

 had isolated hairs all over, as well as a fringe of long hairs at its 

 border. 



