ae : re te, ms " g wee) LF ia! 
516 
and are provided with enormously long spines, many 
times the length of the body, which effectually pre- 
vent their being swallowed by small animals. The 
development of the spinous protection would seem to 
be correlated with the absence of a swimming-tail. 
Some species (Pinnotheres, Tatuira) which do not 
possess any of these spines show a tendency toward 
a modification of the telson, which has in these cases 
become quite broad and flat. 
We may assume, then, that at one time the deca- 
pods, or the stem from which they arose, universally 
possessed a larval stage somewhat similar to the form 
known as a protozoea. As the struggle for existence 
became more and more severe among the Crustacea, 
modifications arose which took two directions. The 
adults became changed; and there arose in this way 
the different types which we know as Anomura, 
Brachyura, and Macrura. But at the same time 
natural selection had its influence upon the free larvae 
quite independent of its influence upon the adult. 
The larvae, therefore, also became slowly modified for 
their own protection; and from the protozoea arose 
the zoea types, with their infinite variety. It is quite 
evident that these changes may take place in the larvae 
without materially affecting the adult, for the cir- 
cumstances bringing them about influence the larvae 
alone. Still it is probable that habits and form of 
the adult may have some influence upon the general 
shape of the larvae. The larva must eventually 
transform itself into the adult; and the more nearly 
it approaches the adult form, the less radical will be 
the change. We can therefore understand why the 
zoea of the walking animal, such as the crab, would 
develop protective apparatus, while the zoea of the 
rapidly-swimming Macrura would acquire organs of 
flight. We have therefore an explanation of the two 
facts, that the larvae of the greater groups exhibit a 
certain unity, while within a given genus the differ- 
ent species may widely vary. H. W. Conn. 
THE EXPLOSIONS ON THE UNDER- 
GROUND RAILWAYS OF LONDON. 
THE explosion of Feb. 25, at the Victoria station, 
London, lends interest to the official report of Col. 
Majendie, on the results of an investigation of the cir- 
cumstances attending the explosion near the Praed 
Street station, on the 30th of October last, and the 
one between Charing Cross and Westminster stations. 
The first explosion occurred in a tunnel about a hun- 
dred and thirty-eight feet distant from the station, as 
the 7.52 P.M. train was passing. The damage in the 
tunnel consisted of a vertical crater in the wall about 
twelve by thirteen inches, and four to six inches deep. 
Immediately below this crater, and extending about 
fifteen inches along the wall, was a horizontal crater 
about six inches deep, partly in the ballast, and partly 
in the brick footing of the tunnel. The flinty ballast 
in this crater was considerably splintered, and the 
brick footing pulverized. A two-inch iron gas-pipe 
ran along the wall at a height of ten inches. A length 
of this, measuring fourteen feet, was blown away, one 
SCIENCE. 
[Vou. IIL, No. 64, 
end being much torn and twisted, and the whole piece 
bent into the form of abow. At a distance of fifteen 
inches from the wall, and parallel with it, was an iron 
switch-rod, consisting of an inch and a quarter gas- 
pipe, supported on iron rollers at the level of the 
rails, from which it was distant two feet nine inches, 
the rollers being fixed on a wooden plank laid on the 
ballast. This board had about four feet of its length 
blown to splinters, and a large piece thrown upon the 
rail, and some of the wheels of the train passed over 
it. A length of the switch-rod measuring about two 
feet, and corresponding exactly with the portion of 
the gas-pipe which sustained the maximum injury, 
was blown out, the central part of this detached 
portion being split up and torn. This piece of switch- 
rod also bore marks of the wheels upon it. A. tele- 
graph cable, running along the wall at the height of 
eight feet and a half, was cut by the explosion. ‘The 
walls of the tunnel were scored somewhat by the 
sharp débris blown against them, and the end of a 
sleeper opposite the crater, but partially protected 
by the ballast in which it was embedded, had a num- 
ber of pieces of splintered stone driven deeply into it. 
The raiis were entirely uninjured. 
The injury to the passing train was confined prin- 
cipally to the last two carriages of the six composing 
the train. In these the greater part of the glass was 
broken into small fragments. Panels and partitions 
were shattered, the roofs and floors disturbed, the 
foot-boards broken, and the carriages seemed to be 
completely wrecked, yet no part of the framing or 
running-gear was injured. The gas throughout the 
train was extinguished, yet the apparatus was found 
to be uninjured. It is interesting to note, that the 
injury to the train was not confined to the side upon 
which the explosion took place, but extended also to 
the opposite side; and in the case of one carriage the 
damage was most marked on that side. Sixty-two 
persons were injured by cuts and contusions from the 
pieces of glass and débris, and, in one or two cases, by 
fracture of the drum of the ear and by severe shocks. 
Five of the injured were confined in the hospital for 
a considerable time. The breaking of the glass and 
putting out of the gas occurred on the surface, at the 
openings of the tunnel, for a distance of three hun- 
dred and fifty feet. 
The second explosion, which occurred almost si- 
multaneously with the first, took place at a point two 
hundred and forty-one yards from Charing Cross, and 
four hundred and eighty-eight yards from Westmin- 
ster. As it occurred opposite a bay, the only damage 
done was the breaking of glass, and the extinction of 
the gas in both stations; the injuring of the telegraph 
and telephone wires for about sixty yards; the for- 
mation of a crater in the ballast, measuring about 
three by four inches, and one inch deep; and the 
‘pitting’ of the walls of the tunnel, on the side of the 
explosion for some little distance to the right and © 
left of the crater, and on the opposite side for a some- ~ 
what greater distance. The rails were entirely un- — 
injured; but the ends of two sleepers, close to the © 
point where the explosion occurred, sustained some 
injury. } 
