of Transformations in Crust aceous Animate. 485 



crabs undergo metamorphoses, when he states (p. 276.) that 

 he has M 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 before 

 their metamorphosis. From their incredible numbers, they 

 were, probably," Mr. Guilding says, " immature Paguri." 



As to the sessile-eyed Malacostraca, some of them, also, ap- 

 pear to leave the egg perfect. Olivier (probably following 

 De Geer and GeofFroy), in his description of the genus Gam- 

 marus Lin., says, (i These insects (as he calls the crevettcs) 

 do not undergo any transformation ; and they have, at their first 

 appearance, the form which they preserve throughout life ; but 

 they change their skin many times, according to their growth. 

 The cast skin shuts to again so closely as to have the sem- 

 blance of the insect itself." {Encyclopedic Methodique, Insect es, 

 vol. vi. p. 183.) 



Mr. Montagu, also, in the Lin. Soc. Trans., vii. p. 67., 

 describing Cancer Phasma (Caprella Leach), says, " While 

 examining a female in a watch-glass of sea-water, under a 

 microscope, we were agreeably surprised to observe not less 

 than ten young ones crawl from the abdominal pouch of the 

 parent; all perfectly formed, and moving with considerable 

 agility over the body of the mother ; holding fast by their 

 hind-claws, and erecting their heads and arms." 



On the other hand, Dr. Coldstream has given us a figure 

 of what he calls the foetus of the Limnoria terebrans. In 

 the Edinburgh Philosophical Journal (xvi. 325.), he says, 

 " Within the sac there are generally found six or seven young 

 Limnoria? : in some individuals only five, in others nine. 

 They have come under my observation always in an advanced 

 stage of developement ; but I have never seen them give any 

 signs of life. The head, and the other five anterior segments, 

 are larger, proportionally, than in the adult. The antennae and 

 eyes are almost completely formed, although the articulations 

 of the former are not distinctly seen ; the colour of the eye 

 is nearly as deep as in the adult. The other appendages hang 

 loosely from the inferior surface : all present the appearance 

 of simple tubiform organs. Even the jaws and the branchiae 

 can scarcely be distinguished from the legs." 



There is, evidently, a wide field open in this subject for 

 investigation ; and, since the intimation given in a note in Mr. 

 Kirby's lately published treatise \_On the Power, Wisdom, and 

 Goodness of God, as manifested in the Creation of Animals, and 

 in their History, Habits, and Instincts'], your readers will, I 

 am sure, in common with myself, look with eagerness for the 

 result of Mr. Westwood's labours in it. 



Norwich, Aug* 12. 1835. 



