4 J 44 Notices of New Books. 



was, then, in the year 1778, that Slabber published a small work, in 

 which occurs a description with figures of a new crustacean animal 

 (fig. «), to which the name of Zoea Taurus was afterwards given. 

 Having taken at sea several specimens of this singular creature, he 

 placed one of them (a) in sea water, which he constantly renewed, for 

 the purpose of observation, and, * on the third day, finding its move- 

 ment become slower and its colour paler, he subjected it to the micro- 

 scope, and found to his surprise that the anterior part of the animal 

 had changed its form, and on the fourth day it had acquired the ap- 

 pearance represented in fig. b, so that, together with the other indivi- 

 duals he had taken, it seemed to have experienced a complete meta- 

 morphosis ; under this new form the dorsal spine had disappeared, 

 the front spine had become comparatively small, the antennae were 

 rendered conspicuous, the feet and eyes were apparently more deve- 

 loped, and the tail had changed from forked to spatulate, fringed by a 

 row of thirteen short spines.' It would certainly seem that this plain 

 and simple statement, supported as it was in many respects by Mr. 

 Thompson's own subsequent observations, can scarcely justify the 

 conclusion to which that gentleman is led, 'that Slabber lost his Zoea, 

 in changing the sea water, and that the new form came from the added 

 portion.' But the truth of Slabber's statement, and, consequently, 

 the evidence of the correctness and originality of his discovery, are 

 very strongly proved by the almost absolute identity of the second 

 form of his animal with that of several species subsequently observed; 

 and particularly of the ditch-prawn {Palcemon varians), as figured by 

 Capt, Du Cane. 



"It was, however, from this observation of Slabber that Mr. Thomp- 

 son, in the year 1823, was induced to carry out the investigation. In 

 the spring of the previous year, as he informs us, in the harbour of 

 Cove, he first met with Zoeas, and that in considerable abundance ; 

 and ' in the year following, at the same season, one of considerable 

 size occurred, amongst a number of smaller ones, and, judging it full 

 grown, he considered it a fit subject to keep for the purpose of wit- 

 nessing the metamorphosis observed by Slabber] &c. The metamor- 

 phosis was interrupted by the death of the animal when in the act of 

 undergoing it ; but it had advanced sufficiently to show that the ani- 

 mal belonged to the Brachyura, and the portion which was observed, 

 contained all the five feet on one side, the anterior foot being furnished 

 with a perfect claw ; and it appears now more than probable that the 

 form into which it was passing was that of Megalopa, to which further 

 reference will be presently made. 



