984 THE AMERICAN NATURALIST. [Vor. XXXV. 
back upon the body and thus to change its direction of move- 
ment, than it is to move bodily backward. 
As in other nemerteans and in turbellaria, the body is 
always covered with a thin layer of slime or mucus secreted by 
the dermal glands. Any stimulation or irritation causes an 
increase of this secretion to such an extent that the animal 
becomes enveloped in a thick layer of the substance. The 
animal is able, like many other related forms, to move beneath 
the surface film, and presumably this secretion is an important 
factor in locomotion here and elsewhere. 
Small dishes in which a number of specimens are kept 
become filled with long strands and masses of the slime, in 
which the animals move about. The accumulation of the secre- 
tion does not appear to injure the animals in any way. Wilson 
(00) has noted the large amount of slime secreted by Cerebrat- 
ulus, and his observations are paralleled by my own. Certainly 
for so small a form as Stichostemma the amount of this slime 
secreted is extremely large. 
RESPIRATION. 
Respiration undoubtedly occurs through the surface of the 
body. The swallowing of water which Wilson (00) has 
observed in Cerebratulus has never been seen in Stichostemma. 
The animals are apparently sensitive to changes in the oxygen 
content of the water, but their small size and the absence of a 
cuticle probably render special respiratory organs unnecessary. 
Foop. 
The only food which the animal is known to take consists 
of specimens of Nais which are captured and gradually drawn 
into the alimentary canal. The actual capture of these animals 
has never been observed, although in several cases they have 
been seen in the partially digested condition in the alimentary 
canal, and in one case a specimen was found with a large Nais 
partly swallowed. The Nais was as long as its captor, and 
although half its body was in the alimentary canal of the 
