306 



ANNUAL REPOllT SMITHSONIAN INSTITUTION, 1924 



representative of the youngest year class (the O group), and a few 

 specimens of greater length than the majority would simply be i-e- 

 garded as born somewhat earlier than the rest. On counting the 

 myomeres of the whole batch, however, which was done in the 

 course of the next few daj's, we arrived at an altogether different 

 result, and one which is of interest in more than one respect. It was 

 now found that out of the 150 specimens, 94 belonged to the Ameri- 

 can eel and 56 to the European eel. Figure 12, B and C, gives the 

 respective values separately shown. They are now seen to have an 

 entirely different meaning. The specimens of both species are of the 



46 

 4 



2 



40 



8 



6 



4 



2 



30 



8 



6 



4 



2 



20 



Fig. 12. — European Eel {AnguiUa vulgans) and American EJel {Angmlla i-ostrata) 



Sizes of laiviE from one haul at " Dana " station 837, 30° 47' N.. 62° 27' W., depth 

 about 25 m., June 13, 1920. 



A. — Sizes of total catch. B and C. — Sarao individuals as In A after their identifica- 

 tion by means of counting the myomeres. B. — Anguilla rostrata, all of the O group. 

 C. — Anguilla vulgaris, two of the I group, the remainder of the O group. 



current year class (the O group), but those of the American* eel are, 

 on an, average, larger than those of the European. From this we may 

 conclude that the former species must spawn earlier or grow more 

 rapidly than the latter. Furthermore, we notice that the two speci- 

 mens of the European eel of 43 and 45 mm. are so much larger than 

 the bulk of the specimens belonging to this species, that they must 

 be supposed to be leftovers from the previous year (the I group). 

 Tliese conclusions were frequently confirmed as the cruise went on. 

 Plate 5 shows, in the form of an illustration, the contents of a 

 similar haul. Both serve well to show how delicate an analysis is 

 needed in the classification of material before it can be used as a basis 



