182 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



The following measurements show the proportions of some of the parts : 



Measurements. 



Millime- 

 ters. 



Measurements. 



Millime- 

 ters. 



Length June 27 1894... 



36 

 16.5 



7.9 

 33 

 13.5 



4 



7 



Length of left chela (propodus) 



Greatest breadth of chela (propodus) . . 



13 

 3.6 



7.8 



5 



4.1 



2 



2 







ljength of anteimary flagellum 



Length of right chela (propodus) 





Length of fringing setse 



Diameter of cornea of lateral eye 







This lobster was kept in a small glass aquarium, and. fed with clams and with 

 lobster and cod eggs. It was undoubtedly undersized for its age, having molted about 

 tifteen times. 



The three lobsters raised in 18S6, which on December 10 measured 35,36.3, and 

 51.8 mm., respectively (ISTos. 7, 8, 9, table 35), had probably molted twelve times in the 

 first two instances and fifteen times in the last. 



Lobster No. 10 (table 35). — When this young lobster was brought up accidentally 

 on a lobster pot in Woods Hole Harbor July 18, 1891. it measured only 47 mm. (See 

 colored drawing, plate 20.) If it was hatched in the summer season it must have 

 been a little over a year old, and it is very probable that in this case also there had 

 been fifteen molts. 



The youngest lobsters taken in Casco Bay, Maine, October, 1893 (Nbs. 1, 2, table 

 32), were doubtless hatched in the previous June, and were therefore about 16 weeks 

 old. They had probably passed from thirteen to fourteen molts. 



It is, therefore, clear that the young lobster varies very considerably in its rate of 

 growth, whether under artificial or natural conditions. In a state of nature the young 

 lobsters hatched in June are probably from 2 to 3 inches long when 1 year old. (See 

 pp. 96-99.) 



I will now add a tabular statement of the successive molts of the adolescent lob- 

 sters, whose development has .just been considered. Further details of their history 

 are given in table 34. 



Table 35. — Successive molts of young lobsters and their measurements in millimeters. 



No. of lobster. 



Number of molt. 



Date of 



last 

 measure- 

 ment. 



Age in 

 days. 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



1 (No. 3, table 34).. 









13 



14.2 



15.5 

 16.5 

 15 

 16.3 



18.4 

 19.5 

 2 17. 05 

 18 



21. 2 

 22] 6 

 19.75 

 21 















Sept. 11 

 Aug. 14 

 Oct. 5 

 Sept. 22 

 Aug. 13 

 Sept. 22 

 Dec. 10 

 . do 



107 



79 



105 



94 



80 



294 



2173 



2 173 



2 173 



2 390 



2 (No. 4. table 34) . . 























3 (No. 37, table 34). 



4 (No. 34, table 34) . 



5 (No. 39, table 34). 



6 (No 38 table 34) 







ii 



'12.5 



13.4 

















2 25 

 24 

 25 



29. 5 























28 

 26.6 























18.5 



21.2 













7 (No 17, table 23) 











2 35 

 2 36.3 









8 (No 18 table 23) 



i " 























9 (No. 19, table 23). 

 10 (No 22, table 23). 























251.8 



2 47 



...do.... 

 July 18 

























. 



















1 Approximate. 2 Number of molts, length, or age estimated. 



THE MOLTING OF THE EMBRYO AND LARVA. 



The first cuticular structure formed in the egg is a delicate blastodermic mem- 

 brane, which appears in the later stages of yolk segmentation and has often been 

 erroneously considered to belong primarily to the ovum. It becomes so firmly glued 



