276 Economy of various Crustacea. 



what becomes of the exuviae if, and when, cast.* — J. 0. W. 

 March 23. 1835. 



^Desultory Remarks relative to Points in the Economy of 

 various Crustacea, by the late Rev, L. Guilding. — This natu- 

 ralist sent, in 1831, 123 pages of notes, in manuscript, on 

 subjects which occur in I. II. of this Magazine. We give 

 here most of those that he had made relative to Crustacea. 

 The number of the volume and that of the page, prefixed to 

 each remark, indicate the place of the notice which had excited 

 the remark. The 123 pages of remarks have but one date, 

 given on the last page : it is, St. Vincent, May 1. 1830.] 



(II. 51.) The Metamorphosis of the Crustacea was observed 

 so early as 1789. Dr. Shaw, in the Linn&an Transactions, i. 

 103. tab. 9., has given an interesting account of Cancer stag- 

 nalis, accompanied by rude figures. 



(II. 244.) Mr. Thompson's Discovery is full of Interest. — It 

 is probable that all the species confined to the sea, or which 

 seek it at spawning time, may go through some metamorpho- 

 sis. I have seen a bay a mile in length covered with myriads 

 of little dead crabs bearing formidable spears, such as Mr. 

 Thompson has figured, which had been washed on shore be- 

 fore their metamorphosis. From their incredible numbers 

 they were probably immature Paguri. 



I do not think any change will be found to take place in 

 the terrestrial genera. While in some marine species the 

 eggs are attached by threads in groups of thousands, our 

 mountain crab (which lives in holes about rivulets, occasion- 

 ally entering the water) seems to exclude but few eggs at a 

 time, free and detached, though the operation may be soon 

 repeated. These are retained under the broad tail of the 

 female, and seem to increase in size and obtain nourishment 

 from a milky secretion. In this case, the decapodous young 

 certainly leave the egg perfect, though they remain growing 

 in the same retreat for some time, till their crust is indurated ; 

 existing, it would appear, on this milky secretion, or some 

 food supplied by the parent crab. 



(I. 490.) The Circulation in the Paguri has been but im- 

 perfectly studied. Some species of crabs must be pulmono- 

 branchiate, [from their] residing for months even on elevated 

 dry lands [see V. 477.]; while hundreds of species inhabit 

 always the deeper waters of the ocean. Most crabs, on being 

 captured, emit frothy bubbles, and sometimes with a crack- 

 ling noise. 



* Mr. Thompson (Ent. Mag., April number) has published a memoir 

 upon the pea crab (Pinnotheres), figuring another Zoea as the young; and 

 stating that he saw the ova of the crabs hatch under this form. 



