BRACHYUJRI. 171 



very pale ; and five or six weeks after coming into my possession, it was 

 delineated white, on November 3. — Plate XXXIX. fig. 1. 



Such specimens are rare. I have never seen any, unless of small 

 dimensions. However, they survive as readily as others, and possibly 

 live as long ; but whether attaining full size, without the wanted modi- 

 fication of colour, is doubtful. No one informs me of having seen a large 

 Common Crab tchite. The aspect of such specimens, in theii" earlier 

 stage, is different from that of the ordinary appearance, as may be seen 

 from fig. 9, which is introduced here for the purpose of contrast. 



The specimen, fig. 1, had been taken on the 29th of September ; it 

 mutilated its companion on the 20th of October, without any symptom 

 of itself having suffered. Rejecting food on the 8th of November, it 

 cast its shell on the 9tli ; when the new animal came in, larger than be- 

 fore, and still paler, being now almost white, fig. 2, Its next exuviation 

 was on April 30th, when the new shell coming in again somewhat larger, 

 was stiU pure white, of soft and delicate aspect. — Fig. 3. 



It is surprising to behold a creature of ample size, with which we 

 are familiar, presented in miniature among many of its kmd of darker 

 hue, but by exception clear and polished, and white as the drifted snow. 

 The difference at first sight is unaccountable, — so great and irreconcileable, 

 that the spectator will pause in allowing their kindred. 



The shell now subsisted from April 30, until September 12, when 

 exuviation produced another considerably larger than previously, of the 

 purest white, so clear and transparent, that the place of the interanea, 

 or the organs confined Avithin, shone through its refined substance. The 

 old one remained quite entire, that is without gaping, or any evident 

 separation of the line of union between the hind pair of hmbs, whence 

 the new shell had issued. All the different parts besides remamed as 

 usual in their own proper position. DeUneation of this subject was 

 postponed until Novemljer 10, or about two months ; whereon it may 

 be remarked, that although no sensible enlargement of the animal en- 

 sues, some slight natural or accidental alteration is usually perceptible. 

 It is generally of trifling importance. — Fig. 4. 



In regard to colour, I viewed the preceding facts as satisfactory 



