ALBINISM, AMBICOLOKATION, REVERSAL 29 



in position, and united with the anal fin. In the British Museum collection there is a 

 specimen of Rhombosolea tapirina, in which the eyes are on the left side, the left pelvic 

 is elongate, median and united with the anal ; the right pelvic is also developed, 

 lateral in position, short-based and with only four rays. Kyle (1900A) has described 

 a new genus and species of Flatfish from New Zealand as Apseita thompsoni} Apart 

 from the position of the eyes, which are on the left side, and the presence of two nearly 

 equal but somewhat a.symmetrically placed pelvic fins, each composed of six rays, 

 this fish appears to be identical with Rhombosolea plebeia, a species common in New 

 Zealand ; it is, in fact, merely a reversed example of that species. According to 

 Hutton {1876), such reversed individuals are not uncommon. The same author 

 (Hutton, 1874) has described and figured a reversed example of R. plebeia with a 

 single median pelvic fin united with the anal as usual in the genus, suggesting that 

 reversal is not always accompanied by development of the pelvic of the blind side. 



. 19. — Optic chiasma in Heterosoiilata. a, Anterior part of brain, eyes and optic nerves of 

 Platrunectes platcssa : i, lateral view from the ocular side ; :;, dorsal view. The forebrain 

 and the olfactory lobes have been removed. [After Mayhoff.] B, Dorsal views of anterior 

 parts of brains (with cerebral hemispheres removed), eyes and optic nerves of Paralichthys. 

 frt/i/ornicMS (sinistral species) : i, sinistral individual ; 2, dextral individual. [After Parker.] 

 c, The same of Platjclithvs slellatus (dextral species) : r, sinistral individual ; 2, dextral 

 mdividual. [After Parker.) 



Cunningham- has drawn special attention to the fact that " in a sinistral Flat Fish, 

 whether it is normally sinistral like the Turbot, or abnormally like a reversed Flounder, 

 the viscera are in the same position as in a dextral specimen ; the liver is on the left 

 side, the coils of the intestine on the right. The reversal of the relations of the two 

 sides externally does not affect the relations of the internal organs, which remain 

 constant ". This is exactly what might be expected. In the normal symmetrical 

 fish the liver is on the left side of the intestine ; thus, a fish lying on its left side would 

 have the hver on the blind side, but in one lying on its right side, the liver would be 

 on the ocular side of the abdominal cavity. 



' The type is said to have been deposited in the Natural History Department, University College, 

 Dundee, but it cannot now be found. 



2 Cunningham and MacMunn (1894, p. Sol). 



