MORPHOLOGY OP BATHYNELLA ANL ALLIED CRUSTACEA. 491 
given by Vejdovsky for the type-specimens. Chappuis states 
that some of his specimens reached a length of 2 mm., but it 
is not quite clear that this measurement excludes the an- 
tennules. In any case Bathynella is one of the smallest 
among the Malacostraca ; only some Asellota and Cumacea 
are no larger, and a few Tanaidge are perhaps even a little 
smaller. 
Body. — The body (Text-fig. 1) is subcylindrical and ‘fully 
segmented, and the general aspect of the animal approaches 
that of the more vermiform of the Harpacticoid Copepoda. 
The abdomen appears to be a little more bulky than the 
Text-fig. 1. 
thorax, and, according to Chappuis, it is slightly compressed 
from side to side. The eight thoracic and six abdominal 
somites are separated by well-marked grooves and appear 
to be freely movable, but the cuticle is almost uniformly 
thin, and there is difficulty in seeing the boundaries between 
the tergal sclerites and the articular membranes connect- 
ing them. The tergites of the posterior thoracic and the 
abdominal somites overlap from before backwards, but in 
the anterior three or four thoracic somites there is no over- 
lapping. 
Head. — The head (Text-figs. 2 and 3) is longer than wide. 
It is truncated in front, with no trace of a rostral projection, 
and behjnd it is sharply defined from the first thoracic somite 
by an articulation exactly like those that separate the thoracic 
somites from one another. There is no trace of eyes or of 
