aculei betweon tliein. In others, as in the Tlmniliaek, 

 the two tins are farther a|iart, and the median line 

 between tiieni is armed with one or more spines. 



Of the coloration of the body Fries observed that, 

 in spite of its \ ariability, it is partly characteristic in 

 some degree of different S])ecies — especially that of the 

 under surface. As a natural result of the life led by 

 the Kays, which ;ire bottom-fishes, this side of the body 

 is coiumonlv light and colourless (whitish), and it would 

 appear as yet to be uncertain whether the dark colour, 

 entire or distributed in large spots, where it occurs on 

 the ventral side, aflords trustworthy specitic characters 

 or not. But good characters may be drawn from the 

 sometimes distinctive coloration of the long winding 

 canals and apertures of the ventral system of the lateral 

 line, and tiiese characters are of so much greater utility 

 as being present from earliest youth and persistent in 

 specimens either stuffed or preserved in spirit. The 

 spots and ocelli which occur on the dorsal side of certain 

 species, showing endless variation in size, colour, an<l 

 extent, are utterly worthless as specific characters. 



With regard to the external differences of sex, 

 which have long been known, Fries stated that they 

 are, as usual, less marked in young specimens than in 

 mature individuals, most of the male attributes being 

 cominoidy absent or only rudimentary in the former, 

 and developing in proportion as the age of puberty is 

 approached. In general the females are armed with 

 far more numerous and much larger spines than the 

 males; but this rule is not without exceptions. 



Most of the true Rays are good and esteemed food- 

 tishes. When boiled fresh, their flavour calls to mind 

 that of the Halibut, or is not unlike that of lobster. 

 They mav also be dried and kept till required for use, 

 in which case the fish is scored along the body. In this 

 form they are usually eaten after having been lyed in 

 the same manner as stock-flsh. They are consequently 

 sought after bv the fisherman, and they are in general 

 well distinguished and familiar to all, their vulgar 

 names affording valuable aid in the definition of the spe- 

 cies and their synonymy. Hollberg (1819) knew three 

 Scandinavian species of the genus, the klorocka {Baja 

 radiata), knaqf/racka (Ttuja clarata, -which he called 

 prickrocka), and sidtrocka (Raja hatls). In his Prodro- 

 mus (1832) NiLSSON characterized four, the above-men- 



s. 1103 



tioned species and the lildt/anisracka {li. litifea, which 

 he called U. fi(IUi)ii((i). In 1838 Fries added two, the 

 (jiikrocka [It fnUomca) and plogjenisrocka {R. oxtj- 

 rhynchns). To these six species Mawi supplemented in 

 18.')7 the sdiidnickd { I!, falsarela, which he called .tpdtt- 

 roi-ka); and in 1881 ( "oi.lett described as Scandinavian 

 Lilljehorg's srarthiiksi-ockii (II. iiidrosieiisis). All these 

 forms unquestionably belong to the Scandinavian fauna; 

 but Coi.LETT further established in 1878 another species, 

 Raja hypcrhnrca, to which the said fauna can probably 

 lay claim. These species may be distinguished as follows: 



A: Blimt-snoiitod. Intcriiasiil width more than 



70 % of the distiincc between each nostril 



and the tip of the snout: — Rajaa clavatee. 



(i; 1-toot of the aculei nail-headed. Distance 



between each nostril and the tip of the 



snout 15 °» or h?ss of the breadth of 



the disk - --.. Kaja clavata. 



b: Root (if the aculei grooved. Distance 

 between each nostril and the tip of the 

 snout at least Hi °i of the breadth of 

 the disk. 



a: Upper median line of the tail armed 

 with a series of aculei. 

 ok; Aculei in the median line of the 



back and tail at most about IG.. Raja radiata. 

 Jih: Aculei in the median line of the 



back and tail at least about 24.. Raja hyperhorea . 

 /S; Upper median line of the tail with- 

 out aculei - ---- Raja fal.iareln. 



B: Sharp-snouted. Internasal width less than 



70 % of the distance between each nostril 



and the tip of the snout: — Rajaj L-eves. 



a: Ventral side light, plain, without dark 



punctuation. 



«; Upper median line of the tail with- 

 out aculei - Raja fidlonica. 



(i: Upper median line of the tail arm- 

 ed with aculei Raja liiitea. 



b: Ventral side dark or marked with small 

 dark dots and streaks. 

 «: Length of the snout less than 18 % 

 of that of the body or than 28 'i 



of the breadth of the disk Raja balis. 



li: Lensth of the snout more than 18 f.' 



of that of the body or than 28 'i 



of the breadth of the disk. 



aa: Aculei (even if small) at the 



eyes. Ventral side blackish and 



with indistinct punctuation Raja nidrosiensif. 



bb: No aculei at the eyes. Ventral 

 side comparatively light and 

 with distinct dots and streaks.. Raja o^ryrhynchus. 



Rcandinm-ian Fishes. 



