SCIENTIFIC SUMMARY. 
115 
birds to avoid eating them, were simulated by the females of another group 
which had no smell, and might otherwise fall ready victims to birds. By 
their great resemblance to the obnoxious butterflies, the scentless females 
were enabled to escape pursuit and deposit their eggs. In different regions 
there were different species, thus imitating and being imitated. This case 
is a crucial test of the truth of the Darwinian doctrine. The females least 
like the Heliconidse had always been more subject to destruction, and con- 
sequently, by the process of natural selection, the present state of very close 
resemblance had resulted. 
Specific Relations of the Pig. — M. Sauson asserts that the domestic pig is 
not descended from the wild boar j the pig having only five lumbor vertebrae, 
whilst the boar has six. 
The White Ant. — The Rev. T. Barry of St. Jude's, Randwick, asserts that 
the only timber that can effectually resist the white ant is the Jarrah, or 
Western Australian mahogany • which is never eaten nor never decays in 
the ground. 
The Dog , the Ara , and the Frog. — These animals, according to one of our 
contemporaries, have disappeared from Martinique and Gaudeloupe, since the 
French occupation. 
A Rare Sponge. — The British Museum has lately received a series of 
specimens of the beautiful sponge called Venus’s flower-basket. — ( Euplectella 
speciosuni). 
Echinus Lividus.—Pv. Alcock, in a paper read before the Literary and 
Philosophical Society of Manchester, described particularly the mechanism 
of the teeth and jaws of this animal. He showed, by a dissection of the 
parts, that the statement made both by Professor Owen and Professor 
Rymer Jones, that the striated surfaces of the jaws are used to comminute 
the food is incorrect, for the whole of these surfaces is occupied by muscle, 
and is altogether outside the pharynx, through which the food passes. The 
specimens examined by Dr. Alcock were from Roundstone Bay. 
An Acarus in the Pigeon . — In the last number of the Microscopical Jour- 
nal , Mr. Charles Robertson, Demonstrator of Anatomy at Oxford, describes 
a hitherto unknown species of acarus, which he found when dissecting a 
pigeon. He states that the specimens found by him are small, oval, white, 
maggot-like animals, distinctly visible to the naked eye, and are found 
chiefly amongst the connective-tissue of the skin, the large veins near the 
heart, and on the surface of the pericardium. When few are found, they 
generally adhere closely to the surface of the pericardium, and to the large 
veins near the heart j if the veins have been previously injected with size 
and vermilion, the white transparent acari are seen very distinctly on their 
red delicate walls. All the examples which Mr. Robertson examined 
were very transparent without any trace of well-defined digestive or 
generative organs, even when examined with the highest powers. The 
body does not generally present any trace of constrictions, but in a few 
examples one or two faint lines were observed, giving the body a seg- 
mented appearance, but this may be caused by a mere folding of the soft 
cuticle. On the anterior and inferior surface of the body a ridge extends 
inwards and downwards from the base of the anterior pair of legs, and unites 
with a median single backward ridge. A similar ridge runs in the same 
YOL. YI. — NO. XXII* K. 
