REPORT OF COMMISSIONERS OF INLAND FISHERIES. 161 



the zoea or free-swimming stages, and the megalops, the first stage 

 in which the lobster assumes the form and, to some extent, the habits 

 of the adult. Next, according to Williamson ('04), comes the mega- 

 lops, which seems most comparable to the fourth stage of Homarus 

 americanus, and then the "first-young" stage, so-called, which is 

 represented by the fifth stage of the American lobster. Some writers, 

 as R. Q. Couch ('43). have assumed the existence of a protozoea stage. 

 Chad wick ('05) .also has published, according to Williamson, a de- 

 scription of a protozoea stage, three zoea stages, a megalops and a 

 "first-young" stage. It would seem probable, however, that there 

 may be reasonable doubt of the existence of this protozoea stage, and 

 that what the observers have actually seen is but an occasional 

 variation which sometimes presents itself in the first zoea stage and 

 not a separate stage. 



We note, on the other hand, that such observers as Appellof ('99- 

 '01) and Ehrenbaum ('03) make mention only of the stages which 

 correspond very nearly with the first stages of Homarus americanus 

 as described by Herrick ('95) and the writer ('05). Likewise in the 

 reports of the duration of the early stage period of Homarus vulgaris 

 there is wide variation. 



Chadwick ('05) states, according to Williamson, that with the 

 exception of the protozoea stage, each of the first five stages of the 

 European lobster lasts about a week. It seems hardly credible, 

 however, that the length of the stage periods should be so nearly 

 the same; and especially that the fifth should be no longer than the 

 first. Appellof ('99-'01) and Ehrenbaum ('03), as we shall see, give 

 quite different reports regarding the stage periods of the European 

 lobster. 



The hatching period for the European lobster extends from the 

 middle of July to the middle of September. The first stage lobster, 

 according to most observers, is about 8 mm. in length. W^e have 

 examined the drawings made (to scale) by Williamson ('04), and con- 

 clude that the lobsters examined by him on the west coast of Scotland 

 were, in length, as follows: 



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