— 19 — 



number of anal and of dorsal rays have likewise been omitted, a preliminary 

 examination having shown that these correlated closely with the number of vertebrae. 



The investigations of Zoarces have been carried out with the assistance of 

 Hr. cand. mag. A. Strubberg, Hr. stud. mag. P. Jespersen, Frk. E. Fasting, and 

 Capt. G. Hansen. The calculations were made by Frk. cand. mag. Kirstine Smith. 



Figure 1, partly based upon material from previous investigations (First Report 

 on Eel Investigations, 1913) gives a graphical view of the number of vertebrae in 

 a series of samples of the European eel [Anguilla vulgaris). The samples were 

 taken at places so widely removed as the Azores, Copenhagen, Iceland, 

 Bayonne (Bay of Biscay) and Comacchio (Adriatic). These samples, differing so 



Fig. 1. No. of vertebrae in 5 samples of the European eel. Graphical view. 

 The curves represent (from left to right) samples from tlie Azores, Copenhagen, Iceland, Bayonne (Bay 



of Bisca3') and Comacchio (Adriatic). 

 The figures along the vertical line indicate no. of vertebrae. A horizontal distance of 30 mm. repres- 

 ents 25 specimens. 



greatly in point of origin, exhibit a conspicuous similarity as regards the character 

 in question. The most frequent variant is throughout 115, the range of variability 

 is 7 — 9, and the average values lie very close together, viz; between abt. 114.6 

 and 114.8. 



By way of comparison, we may now proceed to consider some samples of 

 Zoarces. Fig. 2 gives a graphical illustration of the number of vertebrae in a 

 sample from the North Sea (Esbjerg) and another from the Baltic (Bornliolm). 

 The figure has been drawn in the same manner as in the case of the eel samples in 

 Fig. 1. It is at once seen that the graph for Zoarces presents a strong contrast to 

 that for the eel, a very great difference being noticeable between the two samples, 

 of which that from the North Sea averages 111.323 while that from Bornholm has 

 an average of 117.848, or a difference of fully 6.5 in the number of vertebrae. 



It is, moreover, not only in this respect that the samples of Zoarces examined 

 were found to differ greatly; the same applies to the number of pectorals \ of hard 

 rays in the dorsal, and of pigment spots on the same. 



' The number of pectoral rays varies in the Zoarces from 16 to 21. 

 upon 1 ray have been found in samples from Danish waters. 



Average differences of close 



3* 



