PIKE-PERCII. 
37 
Fisk., p. 22; Heck., Kn., Susswasserf. CEsterr., p. 8; Gthr., 
Brit. Mas. Cat., Fish., I, p. 75; Winth., Naturh. Tidskr. 
Kbhvn 1879, p. 7; Fedders., ibid., p. 72; Lillj., Sv., Norg. 
FisJcar, I, p. 59. 
Var. 1. spec. dist. ? : squam. corp., coec. pyl., rad. pinn. an. 
paucioribus. 
Perea volgensis, Pall., It., I, p. 461; Cuv., Val., 1. c. p. 117 
et vol. VII, p. 441; Nordm., Demicl. Voy. Russ. Mer., Ill, 
p. 363, lab. 1, fig. 2; Heck., Kn., 1. c., p. 12; Gthr., 1. c., 
p. 74. 
Forma americaua: operc. acul. 
Var. 1. spec, dist.?: squam. corp. et coec. pyl. plur. ; rad. pinn. 
an. paucior. 
Lucioperca canadensis Sm. in Griff. Cuv. Anim. Kingcl., X. 
p. 275; Joed, et Gilb. ( Stizostedium ), Syn. N. Amer. Fish., 
Bull. U. S. Nat. Mus., N:r 16, p. 526. 
Lucioperca grisea, De Kay JY. Y. Fn., Fish. p. 19, tab. 68, 
fig. 221 ( canadensis ); Gthr., 1. c. p. 76. 
Var. 1. spec, dist.?: square, corp. et coec., pyl. paucioribus; 
rad. pinn. an. plur. 
Perea vitrea, Mitch., Suppl. Amer. Month]. Mag., II, p. 247 
Jord. et Gilb. ( Stizostedium ) 1. c., p. 525. 
Perea sahnonea, Rafin, Amer. Monthl. Mag. V, p. 354. 
(sec. Jord., Gilb.). 
Lucioperca americana, Cuv., Val., 1. c., II, p. 122. 
Lucioperca lucioperca, Kirtland, Rep. Zool. Ohio , p. 190, 
(sec. De Kay). 
Ohs. The list of synonyms for both the species of Pike-perch 
on each side of the Atlantic, which have hitherto been universally 
acknowledged, is intended to prepare the way for a new treatment of 
the question as to their natural relationship to each other. Both in the 
Old World and the New the number of pyloric appendages varies from 
3 to 6 or 7. Our Pike-perch generally has 6, but I have sometimes 
found only 5 ; Cuvier and Kroyer speak of only 4. Jordan and Gil- 
bert state that the variation in Stizostedium canadense is between 4 
and 7. In conjunction with the least number of these appendages (3) 
on both sides of the Atlantic there appear a smaller number of (larger) 
scales on the body, and a deeper (less elongated) form a . In addition 
to these three variations there is, according to most authors, a diffe- 
rence in the number of rays in the anal fin. Here, however, the 
case is reversed, for in the Old World the greatest number of rays 
in this fin is a character of the variety with small scales, while in 
the New it belongs to the large-scaled variety. The last named diffe- 
rence is, however, according to Jordan and Gilbert, not universal. 
The importance of these differences may be variously estimated, either 
as constituting a distinction of species or only of variety. The ana- 
logy in their tendency in both continents is highly remarkable. If we 
disregard the difference in colour — the American Pike-perch being 
without the transverse black bands on the back and the sides being 
more like brass in colour or having distinctly marked longitudinal 
lines, running in an oblique direction, of brass-coloured spots - — ■, the 
only essential difference in form between the American Pike-perch and 
the European that has hitherto been observed is in the armour of the 
gill-cover. In two specimens of Stizostedium vitreum, the one 167 
mm. in length and the other 471 mm., which the Royal Museum has 
acquired through the Smithsonian Institution, the smaller specimen 
being from Pekin, Illinois and the larger from Lake Michigan, the 
surface of the gill-cover has a longitudinal bar on the upper part 
which reminds oue of the bar in Acerina or Poly prion, though it is 
much less developed. This bar is continued by a flat spine at the 
posterior upper corner of the gill-cover. In St. lucioperca both bar 
and spine are wanting in older specimens, though the corner of the 
gill-cover is furnished with 2 or 3 dentations in the margin which 
remind one of it. But we can generally find a trace of the bar in 
older specimens, and in smaller specimens (between 200 & 300 mm. 
long) it is usually still clearer, while these specimens sometimes have 
a distinct, flat spine at the corner of the gill-cover. The difference 
in this respect is therefore due to the fact that the American Pike- 
perch has retained a juvenile character which disappears in the Euro- 
pean. To judge by the specimens now before us, St. vitreum has 
several other points of resemblance to St. lucioperca. The longitu- 
dinal diameter of the eye in the specimen of St. vitreum from Lake 
Michigan which is mentioned above, is 17 % of the length of the 
head, and in specimens of St. lucioperca of the same size from 14.4 
% to 14.7 %. But in smaller specimens of the latter species, about 
270 mm. long, the ratio is from 16 % to 17.5 %. The case seems 
to be the same with the only constant distinction between the two 
species that we have been able to discover, namely the comparatively 
greater length of the suboperculum in St. vitreum. In adult specimens 
of the European Pike-perch, even those only 270 mm. long, the least 
depth of the tail is equal to the length of the suboperculum (mea- 
sured along the middle to the end of the dermal flap), but in smaller 
specimens 180 mm. in length, I have found the least depth of the 
tail to be only 88 % of the length of the suboperculum. In the 
smaller specimen of St. vitreum the ratio is 72 %, while in the larger 
one it is 74 °/ 0 , a fact which may suggest the opinion that in this variety 
too it increases with age. Lastly, in order to prove that the structure 
of the fins, at least in the two specimens of the American variety 
which are all I have to judge by, rather strengthens than weakens 
our point that St. lucioperca and St. vitreum belong to one and the 
same species, the fin formula for the larger specimen is given below: 
R. hr. 7; D. b 16/— —1 A. 
2 + 17 
C. x + 1 5 + x ; L. lat. 9 3 : 
--^1 P- 2 + 11+2; V. V 3 ; 
1 2 
In the smaller specimen we have D. 13/ ; A. . 
1 2+16 1 + 10 
Thus, as in the case of the Perch, we seem to have most 
ground for the adoption of only one species of Pike-perch, this spe- 
cies differing, however, more sharply in its local varieties, the safest 
character for which may perhaps prove to be the difference in colouring. 
In comparison with the Perch the Pike-perch is 
more elongated and thicker. The greatest depth of the 
body is at the middle, from which point the body gra- 
dually tapers towards the head and tail. The depres- 
sion in the occipital profile which marks the Perch, is 
* generally absent in the Pike-perch. On the other hand 
tve generally find in the latter a marked depression 
between the two dorsal fins. The length of the head 
“ However, in our specimen of the American St. vitreum as in St. lucioperca, the depth of the body at the insertion of the pectoral 
fins is equal to the distance between the tip of the snout and the hind margin of the preoperculum; and the number of transverse rows of 
scales along the lateral line (about 120 above it) may be included among the variations according to age in our Pike-perch. 
6 According to Jordan and Gilbert D. 13 1 — , according to Gunther D. 14/ . 
° 21 ° 19—21 
