FRESHWATER PRAWN 



193 



five times before reaching the my sis stage. Examples 

 which had acquired a brackish water habitat at Saltram 

 Park, near Plymouth, were found to possess larger eggs 

 than their marine relations, and the newly-hatched young 



FIG. 64. The Freshwater Prawn, Pal&mon 

 serratus, which hatches out at the stage 

 shown in Fig. 69. Half natural size. 



moulted only three to four times before attaining the 

 mysis stage.* But in the south of Europe this species 

 has acquired a purely freshwater habitat, and is known 

 under the name P. varians. This produces larger eggs 

 than the brackish water forms examined by Professor 

 Weldon, and hatches out at a stage much later than the 

 mysis. t In North America the same species has also 



FIG. 65. Peneus, a Marine Prawn. One- 

 quarter natural size. After Fritz Miiller. 



become adapted to a freshwater life. Although practi- 

 cally the same species, it is distinguished as P. potiuna ; 



* Weldon, Journ. Marine BioL Assoc., vol. i., n.s., 1889, p. 459. 

 f Paul Meyer, Mitth. Staz. Neaple, 1880, p. 197. 



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