240 



were included, so that the numbers might be comparable with the results I had obtained 

 for the females of the European eel. In order to make sure of always having absolutely 

 correct figures the work was carried out in the following manner, first of all I counted 

 the vertebrae of numbered specimens, then my assistant in these investigations, Cand. 

 Mag. A. Strubberg repeated the countings independently. If the numbers did not agree 

 on comparing the results, we counted them again and if they did not agree even then the 

 specimen was omitted. 



Number of vertebrae in the European and American eel (9 only considered). 

 (Anguilla vulgaris and Anguilla chrgsypa.) All the specimens longer than 50 cm. 



1. Anguilla vulgaris (October 1905, River Bann, Ireland 

 Average: 114,726. 

 o o o o o 



oooooooooooooooo 



oooooooooooooooooooooooooooooooo 

 ooooooooooooooooooooooooooo 

 oooooooooo 



109 



108 

 107 



106 



105 



104 

 103 



2. Anguilla chrijsi/pa (December 1905, River St. Lawrence, Canada) 

 Average: 107,012. 



00000000000 



000000000000000000 



000000000000000000000000 



00000000000000000000000 



00000000 



The result can be seen from the accompanying Table, to which I may add the 

 information that we also counted ca. 150 female European eels from other localities^ and 

 found that the number of vertebrae also varied in these from 111 — 118 just as in the 

 Irish eels. 



The Table shows that there was a great difference between the American and 

 European eel as regards number of vertebrae, the average in the former being 107-012 

 in the latter 114'726. The form of the curve also is the same in both, and the extent 

 of the variation is almost the same, namely 7 and 8 respectively. In spite of the fact 

 that a relatively large number of specimens was examined, there has thus not been found 

 hitherto a single American eel with so high a number of vertebrae as the lowest found 



with red ink. Two vertebrae are often fused together without such a double vertebra appearing essentially 

 larger than the usual single ones. It is thus necessary to be careful, but the spinous processes easily settle 

 whether it is a double vertebrae or only one. It is reckoned in the comparison as 2 vertebrae. As the last 

 caudal vertebra is very small it is of great importance to clean the end of the column carefully. This done 

 the last vertebrae can be counted with certainty under a lens. But it is necessary to be quite clear over the 

 structure of the last two caudal vertebrae, otherwise cases of doubt may arise. With exception of the last, all 

 the vertebrae have the form of an hour-glass (cf. Fig. 4, PI. XXIV in Robin, 1880 I.e.). The hindmost 

 vertebra of this form is taken as the second last and the rest of the column as one vertebra. 



I These numbers will be published later in more detailed form. In one (Italian) specimen 119 vertebrae 

 were found. 



