On some West-Australian Fntomostraca. 7 
oval form, being broadest somewhat in front of the middle, 
and slightly narrowed posteriorly, with the edges quite 
evenly arched in front and laterally. The posterior sinus 
is broadly rounded at the bottom, and is edged with from 
24 to 30 small denticles. On the lower edge of the cara- 
pace there are only 3 or 4 very small serrations close to 
the posterior corners, whereas, according to Messrs. Spencer & 
Hall, they extend to about half the length of the carapace. 
The dorsal carina is quite smooth in the specimen examined 
by me, and gradually vanishes anteriorly, for which reason 
its exact length cannot be stated; it terminates at the bot- 
tom of the posterior sinus in a slightly projecting pro- 
minence. The cephalic part of the carapace, defined by the 
strongly-marked cervical furrow containing the transversely 
convex mandibular segment, but little exceeds half the 
median length of the remaining part of the carapace, whereas 
in the figure given by Messrs. Spencer & Hall, it almost 
equals this part in length The exposed part of the body 
is subeylindrie in form, though gradually tapering somewhat 
distally, and exhibits about 28 segments, of which the 12 
posterior are without legs. They are, as usual, provided 
dorsally with a transversal row of short stout spines, which, 
on the non-limb-bearing (caudal) segments, extend also 
around the ventral side. The terminal caudal segment, to 
which the name of telson can scarcely be applied here, is 
about twice as broad as it is long, and somewhat flattened, 
expanding a little distally, with the hind edge slightly 
emarginated (see fig. 5). It carries dorsally a single, stout 
median spine near the hind edge, and has moreover on each 
side, in its anterior part, a small circular area carrying a deli- 
cate sensory bristle, and flanked in front by 3 denticles 
(see fig. 6). Outside the bases of the caudal filaments, a 
