416 Dr. Baird on some British Entomostraca. 
Genus 3. CantuocarpPus, Westwood MSS. 
Foot-jaws small, simple ; second or inferior pair of antennz 
simple ; ovary single.’ 
The Cyc. minutus, Mill., is the type of the genus. 
Genus 4. Arpacricus, M@. Edwards. 
Foot-jaws possessing strong hooked claws at their extremity ; 
second or inferior pair of antennze simple ; external ovary single. 
The Cyc. chelifer, Mull., is the type of this genus. 
Genus 5. AtreutHa, Baird. 
Foot-jaws small, simple ; body flat ; two strong faleiform ap- 
pendages from fifth segment of body. 
The Cyclops depressus, Baird, is the type and only known spe- 
cies of this genus. 
Genus ARPACTICUS. 
Spec. A. nobilis, Baird, Trans. Berw. Nat. Club, 1845. 
Fi. IX. 2.6; 
Thoracic and abdominal portions of body distinct from each 
other. The thorax is composed of four segments and is large 
and rounded. Abdomen consists of six slender segments, the 
last bilobed, and giving off two long and two short sete. ‘The 
whole insect is beautifully coloured with green, red and purple. 
Hye large, of a ruby colour. Antenne (f. 5 a) short, of seven 
segments, all setiferous ; the two first short and stout, the third 
much longer, toothed on upper edge and giving off at its extre- 
mity several long sete; four last small and short. Antennules 
(f. 5 6) composed of two segments, the first giving off a shoot 
from about the middle of its length, the second terminating in 
several stout sete. The mandibles and anterior or first pair of 
foot-jaws are strong, and resemble the same organs in Cyclops 
quadricornis. Posterior foot-jaws (f. 5 c) shorter and stouter than 
those of typical species, and consisting of two joints and a ter- 
minal hooked claw. Thoracic pair of feet (f. 5 d) differ from ab- 
dominal ones. They consist of two stalks rising from a common 
base ; the anterior or upper stalk consisting of one long joint, and 
a very short one which terminates in a strong claw ; the posterior 
or inferior stalk is very short, toothed on the edge and giving off 
several stout sete. The abdominal feet resemble those of the 
typical species, the setae with which they and the fulera are pro- 
vided being all plumose. The fulcra are the same also as in the 
other species. The sete of the tail however are not plumose. 
This species is at least three times larger than the chelifer, and 
has the body more rounded and much stouter. 
Hab. Berwick Bay. 
