50 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
The type, No. ————.,, United States National Museum, was taken 
in a trawl-net outside of the Golden Gate, and was procured by us in 
the San Franeisco market. 
There-are apparently three species Of the genus Plewronichthys, as 
restricted by Gill, in the waters of California. 
One of these is the common species in the San Franciseo markets at 
present, being taken in some abundance in the trawl-nets off Point 
Reyes and the Farallones. This species is the Pleuronichthys cenosus 
of Lockington’s Memoir (Proc. U. 8. Nat. Mus. 1879, 97), and, 
Lockington suggests, it is probably identical with the Pleuronectes 
gquadrituberculatus of Pallas. For this form we accept provisionally 
the name quadrituberculatus. 
A second species occurs farther south, two specimens having been 
procured by us at Santa Catilina Island, and one at San Luis Obispo. 
This form answers better than the preceding to Girard’s description 
of his Plewronichthys canosus, and it may for the present be identified 
with it. The specimen noticed by Lockington as “ No. 4,” “with the 
dorsal not continued downward nearly so far as the others,” perhaps 
belongs to this species. 
The third species is P. verticalis, described above. 
The species may be readily separated, so far as we have observed, by 
the following characters: 
* Dorsal fin beginning on the level of the lower lip, about ten of its anterior rays 
being on the left side; ocular region with four or more blunt prominences or 
tubercles, arranged as follows: one in front of uppereye, another at each end 
of the interorbital ridge, the posterior largest, but not spine-like, one behind 
the latter, and one or two more behind the upper eye ; upper part of opercie 
uneven; lower jaws with a band of teeth on the right side similar to that on 
the left side, but narrower; fins high, D. 72, A. 46....QUADRITUBERCULATUS. 
** Dorsal fins beginning on the level of the upper lip, only four or five of its rays being 
on the left side of the median line. 
/ 
t Posterior prominence of interocular ridge developed as a strong backward- 
directed spine; tubercular prominences present about the upper eye ; no teeth 
on right side of lower jaw; fins rather low, D. 65, A. 45..-.-.-.. VERTICALIS. 
t{ Posterior prominence of interocular ridge scarcely elevated ; other ocular tuber- 
cles) obsolete); teeth )?; fins high; D; 68, A. 48 222-2222. 2-4 ee nee C@NOSUS. 
Measurements. 
Verticalis. Quadrituberculatus. 
Pi xtreme nen och Inn Ches sce. cece ooo om see neal te Soe ceeceetsise sts 9. 20 11. 85 
enoth to base’of caudal, in inches—1.00..----- 5-2... 2 connie == fej00'— 12.00 9,20 = 1. 00 
Bodyeorestestdepinitnccsre= acters ssicsepiccicceiece ceeceee see eerecees . 54 . 62 
Bodyeleastidepthvotatailes sere. shoes se eee nea eee en soe: he oeee eee .14 -13 
Head, VON OUGNEM Soin asec enie se coin te ene eine Salelaibia, oatidomions oseeoeecete «24 - 28 
ead qiliametoriurrorbitni ses icone sc 5) Suc ec cee ac sein ocean 07 083 
Dorsal, distance from first ray to median line...........--..-....--- . 055 cape 
Dorsal, TGP IGRh NENGINR G5 aoe sep osenopo- BecaAnSsOBaoopeasObaseabocce] 218 .19 
Anal, gr reatest G1 Hib Swiss aise Se = sisieibioemisasae ata cis soaps eee eee 13 18 
Caudal, LON SU ese set ae ole we pa cnte sisi eaeclaattiseios cee cece meee «200 . 28 
Pector al, le meth. Pe eae eae see ce led .18 
Ventral, length Bae eines icons eeice cies see Oo ewie se eeetantscaaaeeeee cemee Aili palit 
