228 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
TABLE III. (continued). 
Sinistral Dextral 
FAMILY PLEURONECTIDAE (FLOUNDERS). hes cats a Sans 
( ) individuals. individuals. 
Subfamily Psettinae (Turbots). 
Species sinistral. 
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Lophopsetta maculata (Mitchill). Massachu- 
setts Bay : 5c FEY Std eee 
1 Platophrys spinosus (Peep): Tampa Bay, Fla. 
1Platophrys pavo Bleeker. Kingsmill Isl. 
1Syacium papillosum (Linnaeus). ‘Tampa Bay, 
ae) re et 2. pie wie hs ae 
2Syacium micrurum Ranzani. ‘Rio Fi , 
2 Azevia panamensis (Steindachner). West Pan- 
ATEN ma Rey RAWAL) oe Be Myo ote ee mastuage 
1 Citharichthys sordidus (Girard). San Francisco 
Markets . ; : 
2 Citharichthys spilapt nus Giinther. Rio Nanciee: 
1 Etropus rimosus Goode and Bean. Tampa Bay, 
Fla. 
An inspection of Table III. will show at onée that the conditions of 
the optic chiasmata in the Pleuronectidae are radically different from 
those in the Soleidae and the symmetrical teleosts. In the Hippoglos- 
sinae 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 Psettinae, all sinistral, regularly had the right nerve dorsal. 
Summarizing the whole table, it may be stated that 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 with 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 Johnstone (: 01, p. 116), and 
Pseudopleuronectes americanus, studied by Williams (: 02, p. 34), the 
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. 
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