ARACHNIDA. 275 
a a 
rudimentary condition of the circulation and respiration. Only one Py 
species need be mentioned here. 
Linguatula rhinaria Pilger. 
The worm-like condition of this parasite may be inferred from the 
fact that it was originally described as a tapeworm (Twnia rhinaria), 
but its Arachnid affinities were 
early suspected, and with the de- 
termination of the early stages 
were proven beyond question. 
In the adult, worm-like stage it 
is a parasite in the nasal cavities 
of various animals, especially car- 
nivores, the most common host, 
perhaps, being the dog. 
The larval state occurs in the 
viscera of different animals, but 
more particularly those which are 
herbivorous—the horse, sheep, ox, 
goat, and many others—as well as 
man. 
The migrations between these me. 167.Zinguatula rhinaria: larva ip ser- 
hosts, which are evidently an es- rata stage—enlarged (copied from Van Ben- 
sential part of its existence, may oat 
be stated in brief to be the discharge of numerous eggs in the nasal 
cavitites of the dog or other host, which, in sneezing or coughing, spreads 
them over vegetation that later is taken as food. by some herbivorous 
animal, and following this ingestion the embryos escape into the glands 
and viscera of the new host, occupying especially the mesenteric glands, 
_ liver, etc., where they remain in an inactive condition until fragments 
of the viscera containing them 
are eaten by a carnivore, when 
they gain access to the nasal 
cavities and become mature. 
In case they have not the for- 
Fig. 168.—Linguatula rhinaria: adult (after Packard). tune to be eaten by a carnivore, 
itis believed they may migrate 
within the body of their herbivore host, reencyst themselves in other 
organs, and even in some cases reach the nasal cavities by way of the 
lungs and air passages, thus accounting for the rare occurrence of 
the adult form in a herbivorous host. 
Curtice' records the occurrence of this species iu America, the larval 
Stage (denticulatum) having been taken from rabbits in two instances, 
once by Dr. fF. L. Kilborne, in 1887, and once by himself, in 1888. 
—_—_- 
) 
: 
f 
‘Animal Parasites of sheep, p. 69, 
