368 Prof. W. Thomson on Steenstrup's views 



without reference to any malformation ; but a more or less per- 

 fect " Cyclopean" position of the eye is so often associated with 

 darkness and plumpness on both sides, that there is every reason 

 to believe there is an essential connexion between the two pecu- 

 liarities. " Double flounders " have always been held in high 

 estimation for the table. The dark side of a Flounder is always 

 the richer ; therefore two dark sides are better than a dark and 

 a light : but the advantage seems to go even further ; for both 

 sides of a double Flounder are plumper than the best side in 

 the ordinary type. " Wrong Flounders " are met with in all 

 species, but usually rarely. In Platessa Flesus they are so com- 

 mon that they can scarcely be regarded as deviations from the 

 normal form : " wrongness " seems in no way connected with 

 structural deviation. 



A singular instance exists of a double monstrosity (so far as 

 we know) universal in a species. 



Fabricius first describes Hippoglossus pinguis (PI. XVIII. 

 fig. 3), the " Kalleragleck " of Greenland, a small Holibut very 

 abundant and constantly fished in the deepest of the Greenland 

 fiords, sometimes associated with H. vulgaris (fig. 4), but often 

 met with alone and in great quantity, with both sides plump 

 and symmetrical, and the eye in the middle of the head. 

 There seem to be good reasons, from the difference in the form 

 of the teeth, from the differences in the gill-covers and in the 

 distribution of the lateral lines, to believe that H. pinguis is not 

 to be regarded as the double monstrosity of H. vulgaris. 



If this be the case, the "right" form of H. pinguis has not yet 

 been observed, and we know the species only from its " double" 

 monsters. We are still ignorant of the conditions of repro- 

 duction of H. pinguis, which has not yet been described as having 

 either roe or milt. 



In the paper of which the above is an abstract the distin- 

 guished author has clearly made out his principal and most in- 

 teresting point — that a simple torsion of the anterior portion of 

 the head of a Flounder on its axis is insufficient to explain the 

 final position of the eyes; and his direct observations on the 

 " Plagusise" prove that the eye of the blind side actually passes 

 from its own side of the head to the other side — at all events, 

 under the integument and under the subcutaneous tissues which 

 contain the rudiments of the dermal bones forming the support 

 of the anterior border of the dorsal fin, if not actually through 

 the head itself. 



The conclusion specially insisted upon by Prof. Steenstrup in 

 the first parts of his communication — that the eye of the blind 

 side, in crossing to the eye side, passes under the frontal bone, 



