L 172 ] 



Preliminary Report on the Results of Statistical and 



Ichthyological Investigations made at the 



Plymouth Laboratory. 



By 

 Georg Duncker, Ph.D. 



During my stay, from August to October, 1897, at the Laboratory of 

 the ]\Iarine Biological Association of the United Kingdom, I was 

 especially engaged in investigating the variability of Phuroncdes jlesus, 

 Linn., and Siphonostoma typhle, Linn. Of the results so obtained, some 

 of more local faunistic importance are briefly reported here. 



I take this opportunity of expressing my hearty thanks to the 

 officers of the Laboratory, especially to the Director, Mr. E. J. Allen, 

 for their help and kind interest in my researches. A paper containing 

 a full statement of the statistical results has been prepared, and will 

 be published shortly. 



1. Pleuronectes flesus, Linn. 



The ilounders of Plymouth, when compared with those of the Baltic 

 and the south-eastern parts of the North Sea, form a distinct race. 

 The characteristics of this race are : 



1. A high number of fin-rays in the dorsal and anal fin (average, 

 dorsal Gl-62, anal 43-44). 



2. Almost entirely smooth squamation on the blind side. In both 

 respects it is similar to the variety Pleuronectes italicus, Giinther, of the 

 Mediterranean. 



The variation in the number of fin-rays has been studied in 1120 

 individuals, of which 602 (=53-75 per cent.) were males, and 518 

 ( = 40-25 per cent.) were females. Of the males 40 ( = 0-6 per cent.) 

 had the eyes on the left side of the head, of the females only 20 

 ( = 3'8 per cent.). On drawing the curves representing the observed 

 total lengths for each sex separately, a distinct size group, similar to 



