210 CRUSTACEANS. 



scai'cely as much, the tail quite flat, with visible articulations, whereof 

 the last consists of two horizontal fans, with five hairs or bristles on the 

 margin of each. Only six limbs now appear, which are also provided 

 with hairs or bristles, and whose constant quivering produces a vortex 

 in the water by their rapid vibration. I could not discover the an- 

 tennae, perhaps from their extreme tenuity ; nor can I pretend to de- 

 scribe the numerous and complicated organs, whose extremity being that 

 of the head, forked conspicuously. Two large oval eyes, each set in a 

 fluted or channeled frame, somewhat like that of a picture, project from 

 each side. The young are void of any similitude to the parent ; and, 

 unfortunately for the observer desirous of following their progress, the 

 third day always terminates their existence. 



In preceding passages, it is said that the exuviation of the Cancer 

 is probably more frequent among younger specimens, which rather seems 

 a general rule. Yet it may only indicate more rapid increment, in 

 proportion to the total bulk of the subject, compared with the frequency 

 of that process in others. 



A very small mutilated specimen of the Galathea rugosa had been 

 some time in my possession : on the night of February 14, it cast its 

 shell, which separated entire in a single piece. This shell measured 

 only eleven-sixteenths of an inch from the tip of the claws to the ex- 

 tremity of the tail, shewing, at the same tune, what had been overlooked, 

 that the animal had been mutilated of the left claw, and a limb in its 

 vicinity. But the new sheh 1 came in complete ; nor were any of the 

 members at all defective. The limbs, however, were very pale, the 

 body a little darker, and speckled red. On the llth of March this 

 creature was delineated. Another exuviation followed on the 27th of 

 the same month, but I was not sensible of any enlargement, either now 

 or on the previous occasion. This was reserved for a third exuviation, 

 on the 4th of May, when the size was evidently augmented, and a yel- 

 low stripe ran partly down the new shell. In regard to the old shell, it 

 was very entire, and very transparent. Still a fourth exuviation fol- 

 lowed on the morning, when the transparency of the old shell now se- 

 parating, did not appear inferior to that of the former, but no enlarge- 



