No. 399.] MORTH-AMERICAN INVERTEBRATES. 213 
4. Uropoda lateral and superior, outer branch arching over base of 
telson. Body cylindrical, narrow, elongated. 
amily IV. Anthuride 
&. Uropoda lateral. 
c. Abdomen consisting of six segments. 
d. Uropoda with both branches developed; mostly lamel- 
liform. 
e. Maxillipeds with the palp free, the margins of the 
ast two joints more or less setose, never fur- 
nished with hooks. 
f. Mandibles with the distal half stout, very con- 
spicuous, uncovered, or with only the 
anterior margin concealed ; from the base 
towards the middle directed forwards and 
a little outwards. 
g. Mandibles with the rather broad, more 
or less tridentate, cutting edges meeting 
squarely behind the large upper lip ; 
the secondary plate and peculiar equiv- 
alent for the molar well developed. 
First maxillae having the plate of the 
first joint armed with three spines, that 
of the third with many. Second max- 
ille of moderate size, the three free 
plates very setose. Maxillipeds with 
the palp rather broad, very setose. 
amily V. Cirolanide 
g’. Mandibles with the distal part produced 
ope a long SE process, the pair 
; the secondary plate 
and molar haatea. First maxillz 
having the plate of the first joint un- 
armed, of the third, carrying one very 
long spine. Second maxillae small and 
feeble, the free plates almost rudimen- 
tary, with few setze.  Maxillipeds with 
the palp narrowed, not very setose. 
amily VI. Corallanide 
f. Mandibles with the distal half narrow, most 
or all of it concealed by the upper and 
lower lips ; from the base towards the apex 
directed gradually inwards. 
Family VII. Alcironide 
€. Maxillipeds with the palp embracing the cone 
formed by the distal parts of the mouth organs, 
