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Scientific Notices. | 383 
TO THE EDITOR OF THE ZOOLOGICAL JOURNAL. 
Sir, 
Finding in your last number for the current year, page 251, an allusion 
to my discovery of the Metamorphosis in the Decapodvus Crustacea, by 
which I perceive that a degree of scepticism still exists, not only as to 
the facts upon which it is based, but also as to the universality of metamor- 
phosis in this tribe of animals, J have now to state what will I trust convince 
you that if any delusion exists or source of error, it must rather attach 
to M. Rathke than to me; not having seen his work I judge only from 
the analysis with which you have favoured us in your interesting and 
valuable Journal. 
First then, in regard to the Brachyura I have ascertained the newly 
hatched animal to be a Zoe in the following Genera, viz. 1. Cancer. 
2. Carcinus. 3, Portunus.. 4. Eryphia. 5. Gegarcinus. 6. Thel- 
phusa? 7. Pinnotheres. 8. Inachus. . 
The Macrourous genera which I have actually ascertained to be likewise 
subject to metamorphosis, are 1. Pagurus. 2. Porcellana. 3. Galathea. 
4, Crangon. 5. Palemon. 6. Homarus. 7. Astacus! These embrace 
all our most familiar native genera of the Decapoda. With regard to 
Astacus however it will be necessary to be more particular. This genus 
embraces but two species, the A. marinus or Lobster, and the A. fluviatilis 
or River Crawfish; now with regard tothe marine species or Lobster I can 
aver that it does actually undergo a metamorphosis, but less in degree 
than any other of the above enumerated genera, and consisting in a change 
from a cheliferous Schizopode to a Decapode; in its first stage being what 
I would call a modified Zoe with a frontal spine, spatulate tail, and 
wanting subabdominal fins, in short such an animal as would never be 
considered what it really is, were it not obtained by hatching the spawn 
of the Lobster. 
Are we then to consider the fresh water species of Astacus or Craw-fish 
as an exception ? or is there not reason (from the above detail) to suspect 
that this peculiarity may have escaped the notice of M. Rathke? If 
however it should be found otherwise, it can only be regarded as one 
solitary exception to the generality of metamorphosis, and will render 
