162 



REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



First zoea stage 8.0 mm. 



Second zoea stage 10.7 mm. 



Third zoea stage 12.2 mm. 



Fourth zoea stage 14.8 mm. 



Megalops stage 15.0 mm. 



First-young stage 17.4 mm. 



Second-young stage 17.0 mm. 



Third-young stage •. 20 . mm. 



The vahie of this estimate must, however, be lessened because of 

 the manner in which it was deduced by the present writer. Accurate 

 measurements of the lobsters themselves would, no doubt, have given 

 somewhat different results. Concerning the exact length of some of 

 these early stages, we can obtain more satisfactory data from Ehren- 

 baum ('03) and Appellof ('99-'01). The latter observed that the 

 first stage-period might be as short as five days, but averages six or 

 seven days. The results of certain observations made by Appellof 

 and Ehrenbaum on the length and stage periods of Homarus vulgaris 

 may be tabulated as follows : 



Table No. 11. 

 Showing the rate of development of European lobsters in the early stages. 



Appell6f. 



Stage period. 



I 6-7 days 



I 9-10 days .... 

 10-12 days (?) 

 23-28 days. .. . 

 37 and 62 days . 



Length. 



8 mm. 



Ehrenbaum. 



Stage period. 



4-5 days . . . . 



3-5 days 



10 days. . . . 

 17 days . . . . 



24 days 



26 days 



30 days 



3 mo. (?)t. 



Length. 



12-14 mm. 



16 mm. 



17 mm. 

 18-20 mm. 

 21-22 mm. 

 24 mm. 



*No accurate data on the length of Appellof s lobsters are available at time of writing. 



tThese lobsters, four in number, mentioned by Ehrenbaum ('0.3) were kept in Aquaria in 

 water whose temperature was relatively high. This probably accounts for the molting of the.se 

 lobsters (one in February and three in March) during the winter months. As will be shown 

 later, this is not usually the case. 



