CRABS AND SIIKmpS. 219 



If we now submit tlie exuvise in detail to a power 

 of 220 diameters, we shall obtain some interestinsr 

 views of the structure. The slongli of the eyes in par- 

 ticular presents one of the most exquisite objects that 

 jou can behold. They are somewhat pear-shaped, 

 with the facetted portion well defined. It is the ap- 

 pearance of these facets, varying according as the per- 

 fectly hexagonal outline of each or the smooth and 

 glossy convexity comes into focus, that is so peculiarly 

 charming. 



Returning now to the examination of one of the liv- 

 ing Zoeas, you i3erceive that the three pairs of pencilled 

 limbs do not rej)resent any of the true legs ; for the 

 transparency of the integuments allowing the interior 

 to be clearly seen, and the organs of the imago being 

 matured and just ready for sloughing, yon discern, with 

 the most beautiful distinctness, the fingered claws 

 (short and stumpy, it is true, as compared with their 

 perfect form in the newly freed imago) folded down 

 upon the breast within the skin, the second pair as 

 large as these, and traces of others beneath them, — all 

 these forming two great projecting lobes. Slightly 

 movable, beneath the thorax of the Zoea, and oc- 

 cupying a bulk nearly equal to that of the whole 

 shield. 



The circulation of the blood is beautifully clear. 

 Tlie pellucid colourless globules chase each other by 

 starts to and fro, as the eye rests on the outgoing or 

 returning current. It is distinct in some parts where 

 you would scarcely have looked for it ; as all over the 

 lozenge plate of the tail, in the interior of the eyes, 

 throughout the posterior spines of the shield, and the 

 frontal spine. But besides, and apparently indepen- 



