228 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



TABLE III. {continued). 



Family Pleuronectidae (Flounders). 



Subfamily Psettinae (Turbots). 

 Species siuistral. 



Lophopsetta maculata (Mitchill). Massachu- 

 setts Bay 



1 Platophrys spinosus (Poey). Tampa Bay, Fla. 

 1 riatophrys pavo Bleeker. Kingsmill Isl. . . 



1 Syacium papillosum (Linnaeus). Tampa Bay, 



Fla 



2 Syacium micrurum Ranzani. Rio Janeiro . . 

 2 Azevia panamensis (Steindachner). West Pan- 

 ama 



1 Citliarichthys sordidus (Girard). San Francisco 



Markets 



2 Citliarichthys spilopterus Giinther. Rio Janeiro. 

 1 Etropus rimosus Goode and Bean. Tampa Bay, 



Fla 



Sinistral 

 individuals. 







 

 





 





 





34 

 1 



II 

 1 



10 



Dextral 



individuals. 





« SO 



An inspection of Table III. will show at onCe that the conditions of 

 the optic chiasmata in the Pleuronectidae are radically different from 

 those in the Soleidae and the symmetrical teleosts. In tlie Hippoglos- 

 sinao the first four species in the table are dextral, and in every one of 

 their thirty-six representatives the left nerve was dorsal. The three 

 remaining species are sinistral, and in all of their representatives the right 

 nerve was dorsal. In like manner the nine species of Pleuronectinae, 

 all typically dextral, invariably had the left nerve dorsal, and the nine 

 species of P.settinae, all sinistral, regularly had the right nerve dorsal. 

 Summarizing the whole table, it may be stated tliat in all the dextral 

 Pleuronectidae examined the left nerve was dorsal and in all sinistral 

 ones the right nerve was dorsal. These results agree perfectly Avith the 

 observations of those few investigators who have recorded the positions 

 of the optic nerves in flounders. Thus in -the two dextral species, Pleu- 

 ronectes platessa, studied by Cole and JoJinstone (: 01, p. 116), and 

 Pseudopleuronectes americanus, studied by Williams (: 02, p. 34), tlie 

 left nerves are said to be dorsal ; and in the sinistral species, Lophop- 

 setta maculata, the right nerve is reported by Williams (: 02, p. 34) to 



1 Material supplied by the United States Commission of Fish and Fisheries. 



2 Material from the collections of the Museum of Comparative Zoology. 



