On some West-Australian Entomostraca. 15 
probably very variable in different specimens, increasing 
with the age of the individual. 
The enclosed animal (see fig. 4) appears on the whole 
of quite normal structure. In the shape of the head it 
agrees more closely with E. dictyon, the upper part of its 
dorsal face forming an almost rectangular bend at the 
cervical impression, whereas in Æ. Packardi this part is 
produced to a narrowly rounded lobe. The eyes are con- 
fluent, and placed within a well-marked bulging of the 
dorsal surface of the head about in the middle between the 
cervical suleus and the tip of the rostrum. The latter 
appears somewhat blunted at the end, and from it ascends 
on each side the strongly marked fornix, which, at some 
distance beneath the ocular bulging, forms an almost angular 
bend. The ocellus can be only faintly traced at the base of the 
rostrum. The antennulæ are of moderate length and exhibit 
about 10 papilligerous lobes. The antennæ, or oars, are of 
the usual structure, both rami being composed of about 12 
lamellar articulations carrying anteriorly short spines, 
posteriorly slender natatory sete. The legs do not seem 
to exhibit any peculiarity in their structure; their number 
is only 22 or 23 pairs, the last 2 being extremely small. 
The tail (see fig. 5) resembles in shape that of EF. Packardi, 
as described by the present author in the above-quoted 
paper. It has at the base dorsally 2 juxtaposed dentiform 
projections, from which extends on each side a row of 4 or 
5 small denticles, the last occurring somewhat below the 
insertion of the caudal sete. The caudal lamellæ are, as 
usual, produced into strong unguiform projections, which 
are not perfectly juxtaposed, and each of them has the 
slightly concaved dorsal edge armed with numerous (from 
20 to 30) denticles of somewhat unequal size, small den- 
