396 THE VIVARIUM. 
covered with green baize. For food it may be supplied with 
garden worms, river worms (Tubifex rivulorum), fresh-water 
shrimps (Gammarus fluviatilis), water-fleas (Entomostraca), and 
the like. 
The Olm is caught by the Austrian peasants, placed in vessels 
of water, and, when opportunity offers, sold to tourists. It is 
also occasionally brought into this country, and may be bought 
at prices which vary from 7s. 6d. to 10s. 6d. 
It has sometimes, while in confinement, deposited eggs, which, 
after a period of about three months, have produced Tadpoles. 
The larvee are very like their parents, except that the tail fins 
and the eyes are much larger in proportion to the size of the body 
than those of the adult. The legs during the tadpole-hood are 
represented by what may be called small knobs. One adult 
female has been known to lay as many as seventy-six eggs. 
The blood corpuscles, or disks, of the Proteus are immense, being 
about fifteen times larger than those of man. 
P. anguinus has a narrow head, with a long snout, narrowed 
and the tip truncate; a small tongue, free in front; feeble 
vomerine teeth; a small mouth; well-developed labial lobes; a 
long slender body ; two pairs of very weak limbs; three fingers 
on each hand, and two toes on each foot; a short, compressed, 
finned tail, having a rounded end; a smooth skin; about twenty- 
six costal grooves, The colour is pinkish-white, without spots or 
markings. The colour becomes gradually darker upon constant 
exposure to light. 
The Proteus sometimes reaches a length of about 1ft. 
The Siren (Stren lacertina) is a representative of the family 
Strenide, which is divided into the two genera, and Siren and 
Pseudo-branchus, each containing only one species, viz., S. lacer- 
tinw and P. striatus. The chief differences between the Batra- 
chians of these two genera are that the members of the former 
possess three gill-openings on either side of the neck, and two 
four-fingered hands, while those of the latter have only one gill- 
opening on each side of the neck, and three fingers on each hand. 
The Siren is a native of the South Eastern part of the United 
States of America. It is often found in the rice fields there. The 
slaves in days gone by looked upon this Salamander as poisonous, 
