444 
WORMS. 
Different species of the genus Clepsine may be found on the leaves of water- 
plants and on the under side of stones. They are grey, yellow, or whitish in 
colour. Instead of burying their eggs like the medicinal leech, these creatures 
carry them about, and the young after birth remain some time with their mother. 
They live principally upon water-snails and young mussels. The engraving 
on p. 443 represents the rock-leech, Pontobdella muriccita, remarkable for being 
an inhabitant of the sea, and also for having the skin covered with warts and 
knobs. The body, which gradually narrows from the posterior end to the head 
is of a greenish grey colour, and the anterior sucker large and button-shaped. 
During the daytime these leeches usually rest partially coiled up, as shown in the 
lower figure, and firmly attached by their hinder sucker to some rock ; but their 
muscular strength is so great that they are able to maintain themselves extended 
in an almost horizontal direction, as represented in the upper figure of the illus¬ 
tration. They feed upon skates and other fish. 
The Gephyrean Worms,— Class Gephyrea. 
Gepliyreans are marine, cylindrical, worm-like animals, presenting no distinct 
external segmentation of the body, and possessing nothing of the nature of limbs or 
gills. The skin is horny, 
though not calcareous, and 
often provided with tuber¬ 
cles, hooks, or bristles. The 
anterior end of the body is 
furnished with a retractile 
and sometimes highly- 
flexible proboscis, at the 
end or at the base of which 
the mouth is situated; the 
alimentary canal either 
traverses the body from end 
to end, as in Bonellia and 
Echiurus, or is coiled round 
a special spindle muscle, and 
returns upon its course to 
open in the front half of the 
body,as in Sipunculus,Phas- 
colosoma, and Phymosoma. 
In the last-named genus the 
head is furnished with a 
circle or half - circle of 
tentacles. The muscular, 
vascular, and nervous 
systems are well-developed; 
gephyrean worms. latter consisting of a 
A, Bonellia ; B, Phascolusama ; C, Priapulus. (Nat. size.) cerebral ganglion, an ceso- 
