R A I A. 



515 



vidual. The swimming fins on the margins of a 

 flounder we say margins, for they are the upper 

 and under margins, and not the sides are the dorsal 

 and the anal tins, which are the least efficient for 

 motion of all the fins of any fish. They are not 

 directly connected with the spinal column, but have 

 three even bones simply imbedded in the flesh. 

 Whenever, therefore, a fish is thrown upon these as a 

 means of forward motion, that motion cannot be per- 

 formed without a caudal fin, or flexures of the body, 

 or both. Hence the twisting and wriggling of all the 

 flounder tribe when they do move, and the limited 

 range to which their very laborious motion ex- 

 tends. 



Swimming with the pectorals is a very different 

 matter, especially swimming with pectorals so well 

 developed as they are in the skate. The pectorals 

 answer to the fore legs of animals and the wings of 

 birds ; and in fishes the shoulder is always better 

 made out than the support of any other of the body 

 fins. In the skate, which has no caudal fin, and no 

 very useful fin of any kind upon the tail, the blade- 

 bone of the pectoral is peculiarly firm, and the jointed 

 cartilaginous rays in the lobes of the fins admit of 

 verv free, rapid, and consequently powerful motion. 

 The length of the rays gives great rapidity of motion 

 to the margin of the fin ; and as each ray appears to 

 be capable of a separate motion, especially toward 

 the terminal part, the directions and degrees of 

 action on the water are almost countless, fully jus- 

 tifying the comparison that is usually made be- 

 tween them and the most powerfully-winged of 

 birds. 



When a skate is excited, and swims with rapidity, 

 there is still little or no flexure or wriggling of the 

 body, that is to say, of the spinal column, the 

 flexures of the pectoral fins being still sufficient to 

 perform the motion. Indeed, the absence of flexure 

 in the spinal column is one of the means of power in 

 the fins, and far from the least efficient means. In 

 this again they agree with birds, in which powerful 

 flyers alwavs have the spine much stift'er than birds 

 of' feeble wing. Against that part of the length 

 where the swimming fins of a skate have the most 

 powerful effect, the vertebrae of the spine are sol- 

 dered together, and they approach more nearly to the 

 character of the bones of common fishes than any part 

 of the skeleton in those cartilaginous fishes which do 

 not require so powerful a use of the pectorals. 



In all the motions of a skate through the water, 

 the above notices of its structure and action will 

 show that the tail is quite free, and fit to be used for 

 any other purpose. We have already mentioned 

 that the chief purpose of it is defence ; and in the 

 using of it the spine is much rounded, so that the 

 head and insertion of the tail are much more elevated 

 than the middle part of the body. The tail admits 

 ot' flexure in every direction, which fits it for being 

 an efficient lashing weapon, but makes it less adapted 

 for a swimming organ than if its action were confined 

 to one place, as it is in all fishes who depend much 

 upon its use in swimming. We have been somewhat 

 particular in describing the motions and organs of 

 motion of these animals, because, on account of the 

 peculiarity of their form-;, there is a very general 

 notion amoti<j persons not acquainted with the eco- 

 nomy of the sea and its inhabitants that they are very 

 unwieldy and helpless creatures in the water ; whereas, 

 the fact* is quite the reverse, and, even among those 



fishes which are regarded as models of perfection as 

 swimming animals, there are none who have more 

 command, or even as much command of themselves, 

 as the skate. 



As is the case with all animals of great muscular 

 power and activity, skate are very voracious and in- 

 discriminate in their feeding. Their teeth are 'not 

 well adapted for biting, in the ordinary sense of the 

 word, and the mouth being a sort of slit, without very 

 produced jaws, they do not catch their food with a 

 rapid snap of the mouth. The teeth are in curved . 

 tufts, adapted for breaking and bruising ; though the 

 full-grown, or rather mature males, in some of the 

 species, at least, have the same rows of teeth directed 

 backwards, and drawn into sharp but not very length- 

 ened points. They feed upon fishes, and also upon 

 Crustacea and mollusca, whether with shells or with- 

 out ; and the power of the muscles of their jaws, as 

 well as of all the other muscles of their bodies, is 

 understood to be very great. 



GREY SKATE (R. batis) is the skate by way of 

 eminence, and the one of which the flesh is so much 

 esteemed as food. It is very common on some parts 

 of the coasts of Britain, though comparatively rare 

 on others. It is a bold and powerful swimmer, and 

 frequently attains a very great size, sometimes weigh- 

 ing two hundred pounds or more ; but these very 

 large ones are not so much esteemed for food as 

 those that are smaller. The colour on the upper 

 part is dull greyish brown, and that on the under 

 part dull grey, marked with dark spots ; the snout is 

 pointed, and the lines from the broadest parts of the 

 disc to the snout, which are longer than the two 

 remaining sides of the rhomboid, are .nearly straight ; 

 the breadth of the disc of the body is one-thira more 

 than the length ; the hinder part of the disc makes a 

 more obtuse angle than the fore part ; but, if the 

 measures are taken to the extremities of the ventral 

 fins, the two angles are nearly equal ; the eyes are 

 slightly raised above the general surface of the head ; 

 their irides are yellow, and each is defended by one 

 elevated tubercle in front, and another on the inner 

 side ; the vent-holes are near the eyes, and defended 

 by valves ; the dorsal ridge, or rather mesial line on 

 the back, has no spinous appendages as far as the 

 dorsal fins ; but below this there is a single row along 

 the mesial line, reaching as far as the two small fins 

 on the tail, which appear to occupy the place of 

 dorsal fins, and a single one between these fins ; 

 these spines are sharp-pointed, of very hard con- 

 sistency, and have their points directed backwards. 

 The male has also spines on the sides of the tail, with 

 the points directed forwards. The mouth is rather 

 wide, with blunt teeth in the young, and sharp ones 

 with the points inclined backwards in the mature 

 species ; they have this difference between the young' 

 and the adult in both sexes ; whereas in others the 

 change is peculiar to the male. The change begins 

 when the extent of the disc is about fourteen inches. 

 This appears to be the beginning of maturity ; but 

 no limit is known to the subsequent growth. The 

 claspers, or " tasrs," as they are called in some parts of 

 the coast, with which the' male of all the species is 

 furnished, one on each side of the root of the tail, 

 are long in the male of the grey skate, on which 

 account it is sometimes called the three-tailed 

 skate. 



In this, as well as in all the other species that get 

 the common name of skate by the fishermen, the 

 K K2 



