226 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 
We recognize among the Pleuronectide seven subfamilies—Hippo- 
glossine, Pleuronectine, Samarine, Platessine, Oncopterine, Soleine, and 
Cynoglossine. The Samarine and Oncopterine are all of recent discov- 
ery. The other groups correspond exactly to the five “subgenera” 
(Hippoglossus, Rhombus, Platessa, Solea, and Plagusia) recognized by 
Cuvier. These subfamilies are natural groups and are in most cases 
easily distinguished, although some few aberrant genera exist which 
serve as links joining one group to another. Thus Jsopsetta of the 
Platessine is certainly a near ally of Psettichthys, which is as certainly 
a-genuine member of the Hippoglossine. 
The Hippoglossine and the Platessine are largely arctic in their dis- 
tribution, few of the former group and none of the latter extending into 
the tropics. The Oncopterinw seem to take the place of the Plates- 
sine in antarctic waters, but the species of this group are few in num- 
ber. The Pleuronectine and the soles are, on the other hand, essentially 
warm-water fishes, their representatives in the north being compara- 
tively few. The Samarine are few in number and belong to the East 
Indian fauna. 
As the tropical Hippoglossine and all the Plewronectine are sinis- 
tral species, the eyes and color being on the left side of the body, it fol- 
lows that the tropical flounders are nearly all left-sided species, while 
those of arctic and antarctic waters are chiefly dextral species, the 
eyes and color on the right. ‘ 
Still more curious is the relation between the number of vertebrz 
and the geographical distribution of the various species. 
It has been already noticed by Dr. Giinther and others that in some 
eroups of fishes northern representatives have the number of vertebrae 
increased. In no group is this more striking than in the flonnders, as 
the following table showing the numbers of the vertebrae in various 
species will clearly show. The numbers inclosed in brackets are copied 
from Dr. Giinther; the others represent our own count of specimens con- 
tained in the museum of the Indiana University. 
© 
Numbers of vertebree in flounders. 
I.—HIPPOGLOSSIN®. ; 
EPPO LOSSUS DIPPOGIOSSUS) - sce ocean oes ech a cemeeieetesian bs see eee 16+ 34= 50 
Atheresthes stomias 22....025 Gol eee ak Den Sate bie eke ee 
Euppoglossoides platessoides/-4 5.5 20e-sviease teers weet -sa-ae aeeeee 13+32—= 45 
DEPARTS: OVALS. 0.5% fara cece, naa dele ee eR aad kin Ga S vas eee 11+ 34= 45 
HODES ULE JOLCANE «sc -cc'a teen Bot eee ei ee emits moins ean cae a ee 11+ 32= 43 
PROvMCHthys MeLANOstOlUs..«<c< > .criseedeouse nics «con -> += nc abanawen 11+29= 40 
Paralichthys oblongus .......----..----- prleiS Sakicin> se Rene eee 11+ 30= 41 
Paralichthys dentatus.: so.< ce shen ewes co eS oee sees eae . 10+30= 40 
Paralichthys lephostigma....-+siweuebee-es => so6 shook Ven eeee ee 10-++-27= 37 
reralichthys albioutti. 022-6 soir eats bee ome eje oat eee See 10+27= 37 © 
Earaicuthys californious .-:..<40-5 oon sedioe naa te s+ su wiaewenen ye 10+25=> 35 
RPAIPEUEYS WIGIODIG:,..... ~..- scat pi cutee Rone Dette ay 2 on 300s wen Denice 12+ 2= 37 
Almyiopsovia quadrocellata:s.~ 3). vosnce ss veh ee-svces seeceuane ames 9+26= 35 
