RAYS. 
1089 
tached — and the fibre now resembles a club. The 
thick end' (inner or anterior end) soon expands still 
more (fig. 306, B) and is hollowed into a cup shape, 
from the bottom of which the thin end (d) of the 
fibre proceeds in the form of a shaft, the fibre now 
having the appearance of a bilboquet. The body is 
further flattened (fig. 306, C and IJ), and the shaft is 
more and more reduced, until it finally bends quite to 
one side (fig. 306, E) or disappears, the fibre being 
now similar to a flat disk. In the common Skate the 
electric elements pass through all the three stages of 
development, in the Sandy Ray (Baja falsavela ) only 
the first two, in the Starry Ray only the first stage. 
In the electric elements of a Starry Ray, which 
are club-shaped but always somewhat concave at the 
top, the two constituents of the muscle fibre, the sarco- 
plasrna and the rhabdia, are partly separated from each 
other. They have gathered at the thick end more 
densely than in the slender portion of the fibre, and 
a special layer of sarcoplasma, a so-called electric plate, 
is interposed at the top, immediately below that part 
of the sarcolemma where the nerve fibrils are inserted. 
Under this electric plate lies a densely striated mass, 
consisting principally of rhabdia, but containing nu- 
merous muscle nuclei, an indication that a considerable 
amount of sarcoplasma is present. In the cup-like 
(bilboquet-shaped) elements of a Sandy Ray the stri- 
ated layer contains far fewer and more scattered muscle 
cells; and under this part the granular substance (the 
sarcoplasma) has formed a distinct layer with pro- 
cesses and alveoli (sponge-like meshes), a so-called 
alveolar layer. In the common Skate the rhabdia is 
entirely separated from the sarcoplasma and contains 
no muscle nuclei. Each electric element thus consists 
in this species (fig. 306, E) of three plates (a, b, c ), 
one above another, the outer pair (a and c) being, 
however, confluent at the margin. With the addition 
of the secondary growths of gelatinous (/) and fibrous 
(s) tissue that extend into and fill up the spaces be- 
tween the electric elements proper and also support 
capillaries and nerves, we find here, in the common 
Skate, an electric apparatus of essentially the same 
structure as in the Torpedo and Electric Eel. On each 
side of a comparatively firm plate, in section densely 
striated and originally formed of rhabdia, are set layers 
of sarcoplasma differing in their histological structure. 
This difference may perhaps produce different kinds of 
electricity. In that case we should here possess an 
analogue to the well-known galvanic piles. Or per- 
haps the electricity may be of the same kind in both 
layers of sarcoplasma. In the latter case the electric 
apparatus of these fishes corresponds to an agglomera- 
tion of electrophori. 
The manner in which these organs are employed 
by our common Rays is not yet known. Their elec- 
tric faculty cannot be doubted; but thousands of these 
Rays pass through the hands of fishermen without any 
recorded instance of a human being having experienced 
an electric shock from one of these fishes. When a 
Ray feels the resistance of the hook, and the fisherman 
begins to haul in the line, it first endeavours to cling 
to the bottom by clasping its pectoral fins round some 
hard object or tightly pressing them to the ground; 
and when it emerges from the water, it tries to defend 
itself by raising the pectoral fins as a shield for its 
body, bending the tail upwards and forwards, and 
dealing violent blows with the latter member. Now 
the tail of these Rays is so formidably armed with 
large, pointed spines that these in themselves are a 
sufficient warning to the fisherman against handling 
the Ray with the naked hand until he has given it a, 
finishing blow, and hence it may well happen that as 
a rule he has no opportunity of experiencing the elec- 
tric powers of the fish. Whether the electricity is 
utilised in combats with other inhabitants of the deep, 
in self-defence or to stun a victim, is also unknown. 
We know that dolphins (toothed whales) are the worst 
enemies of the large Rays, Ling and Halibut of the 
smaller ones; but Saville-Kent saw dolphins seize 
Rays by the tail, the very part where the electric or- 
gans are situated. From observations in aquaria we 
learn that the Rays secure their prey by casting them- 
selves over it with a sudden movement of the pectoral 
fins, squeezing it under their body, and gliding over 
it, until it can be grasped with the jaws. In these 
operations the tail can evidently serve merely as a rud- 
der to direct the course of the fish. So too, Avhen 
the Rays swim freely about in the water, propelling 
themselves by undulating movements of the pectoral 
fins, the tail can only steer and preserve the equipoise 
of the body. Saville-Kent compares the movements 
of a swimming Ray to those of a wading bird that 
stretches its long legs behind it in its flight. 
The system of the lateral line in the Rays requires 
a special chapter, though it rather closely resembles that 
of the Holocepliali. It is generally far more developed 
