PIKE-PERCH. 



37 



Fisk'., p. 22; Hkck., Kn., Siisstrasserf. (JJsterr., p. 8; Gthr., 



Brit. Mns. Cut., Fisli., I, p. To; Winth., Naturh. Tidskr. 



Kbhvn iST'.t, p. 7; Khddkhs., iliid., p. 72; Lilij., .Sv., Norg. 



Fiskar, I, p. 51t. 

 Var. I. spec, tlisf.'?: sqimiii. eorp., coec. pyl-, rail, pinii. an. 



paucioribus. 

 Perca volgeiisis, Pam,., It., I, p. 4(il; Cuv., Val., 1. c. p. 117 



et vol. VII, p. 441; NoRDM., Demid. Voy. Russ. Mer., Ill, 



p. .•?(;.!, lab. 1, lig. 2; HuCK., Kn., 1. t:., p. 12; Gthk., 1. c, 



p. 74. 



Foiiiia aiueriraiia: (ipcrc. aciil. 



Var. 1. spec. disl.V: squaiii. corp. et coec. ]iyl. plur.; rad. pinii. 



an. paiicior. 

 Liccioperca canadensis S.m. in Ghiff. Cuv. Aniia. Kimjd., X. 



p. 275; JoHD. et Gii.u. {iSlizcHediam), Syn. N. Amer. Fi.'^h., 



Bull. U. S. Nat. Mus., N:r Hi, p. .520. 

 Liccioperca grisea, Ue Kay N. Y. Fit., Fish. p. 19, tab. 68, 



fis- 221 (canadensis); Gthr., 1. o. p. 70. 

 Var. 1. spec, dist.?: sipiam. Corp. et coec, pyl. paucioribus; 



rad. pinn. an. plur. 

 Perca vitrea, Mitch., Suppl. Amer. Moulhl. Mag., II, p. 247 



JoRD. et GiLB. {Stizostedinm) 1. c, p. .525. 

 Perca salmonea, Rafin, .-Vmer. Monthl. Mag. V, p. 354. 



(sec. JoRD., GiLli.). 



Lucioperca americana, Cuv., Val., 1. c, II, p. 122. 

 Lucioperca lucioperca, Kirtland, Rep. Zool. Ohio, p. 190, 

 (sec. De Kay). 



Obs. 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 or 7. Our Pike-perch generally has 0, 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 ". 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 uamed 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 variet}-. 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 Koyal 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 one of the bar in Acerina or Polyprion, 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 comer 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- 

 jierch has retained a juvenile character which disappears in the Euro- 

 pean. To judge by the specimens now before us, St. vilrmm has 

 several other points of resemblance to St. lucioperca. The longitu- 

 dinal diameter of the eye in the specimen of -S'^. vitreum from Lake 

 Michigan which is mentioned above, is 17 % of the length of the 

 head, aud in specimens of St. liccioperca of the same size from 14.4 

 f» to 14.7 'o. But in smaller specimens of the latter species, about 



270 



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. citreuin. 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 ilermal 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 %, a fact which may sugges-t 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 (hat St. lucioperca and St. vitreum belong to one and the 

 same species, the fin formula for the larger specimen is given below: 



1 



/>.'■ 16 - — -; A. 



■2 + li 



1_ 



2 -f 12' 



P. 2 + \\ +-2: V. 



1/ 



R. br. 1 



C. ,r -h 1 5 -t- ,f ; L. lat. 93: 



1 2 



In the smaller specimen we have D. 13 r-;-—;; A. -z—:-rz- 



2-t-lb 1-i-lU 



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 iu colouring. 



Ill comparison with the Percli the Pike-perch is siou in tlie occipital profile which marks the Perch, is 



more elongated and thicker. The greatest depth of the generally absent in the Pike-perch. On the other hand 



body is at the middle, from which point the body gi-a- we generall}- timl in the latter a marked depression 



dually taper.s towards the head and ttiil. The depres- between the two ch.rstil tins. 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. 



1 1 

 * According to Jordan and Gilbert D. IS- — , according to GCsther D. 14 ~ ^ . 



