366 A HISTORY OF RECENT CRUSTACEA 
Haswellia, Miers, 1884 (a new name for the pre- 
occupied Calyptira, Haswell, 1881), has the last seement 
of the perzeon produced into a broad plate or shield over 
and beyond the pleon. The pleon has a terminal qna- 
drangular notch, with a squarish lobe within it. The first 
antennee are broad at the base. The type is Haswellia 
carnea (Haswell). 
Ancinus, Milne-Edwards, 1840, has the body flattened, 
the pleon triangular with a truncate tip; the eyes dorsal 
instead of lateral; the first and second gnathopods sub- 
chelate with long curved fingers; the uropods with only 
one branch, which is long and narrow, and, as in Nesa 
and Campecopea, does not hug the telson. The single 
species, Ancinus depressus (Leach), exhibits considerable 
diversity in the forms of the limbs of the perzeon. 
Scutuloidea, Chilton, 1882, has the body not very con- 
vex, the pereon much broader than the head, the pleon 
broadly triangular, emarginate at the apex, and the 
uropods contiguous to it, very salient, single-branched, 
consisting of a large squamiform plate. The type is 
Scutuloidea maculata, Chilton, from New Zealand. The 
second gnathopods are longer than the other limbs of the 
pereeon. 
Plakarthrium, Chilton, 1882, has the body much de- 
pressed, with the side-plates of the pereeon greatly ex- 
panded, the first pair produced forward at the sides of the 
head, and the seventh pair backwards nearly to the ex- 
tremity of the uropods. The two basal joints of the first 
antenne and the third and fourth joints of the second are 
expanded, enclosing all the front of the head. The pleon 
is rectangular, with the uropods sub-terminal, the outer 
branch short, apically dilated. Plakarthiwm typicum, 
Chilton, found on the seaweed Eklonia radiata, in Lyttel- 
ton Harbour, New Zealand, ‘affords a very good example 
of protective resemblance, for the body being very flat and 
of a brown colour can scarcely be distinguished from the 
seaweed, to which it closely adheres.’ Its position among 
the Spheromidee is somewhat doubtful, if it be the case 
