212 
BRITISH ENTOMOSTRACA. 
into eight very short articulations, having between the 
fourth and fifth a very small lateral joint, as in most of the 
other species. Each articulation sends off one or more 
setae. The antennules are similar to these organs in the 
other species, as are also the posterior foot-jaws, which 
consist of two rounded joints, terminated by a slightly- 
curved hook. 
The first pair of feet does not differ in structure from the 
others, and consists of two stalks, of nearly equal length, 
each composed of three articulations, and each articulation 
giving off two or three setae. The outer branch is more 
slender than the inner. The fulcra or supports consist of 
a broad, flat plate, with several tolerably long setae, as in 
the preceding species. 
Hab. — Berwick Bay, 1835. Dover, North Foreland, 
September 1849. 
Genus 3 — Arpacticus.* 
Cyclops, Muller, Tilesius, Baird, fyc. 
Monoculus, Manuel, Gmelin, fyc. 
Arpacticus, M. Edwards , Baird, Dana (in part). 
Nauplius (pars), Philippi. 
Character — Foot-jaws forming strong cheliform hands. 
Antennules simple. Ovary single. 
1 . Arpacticus chelifer. Tab. XXIX, figs. 2, 3, 3 a-g . 
Cyclops chelifer, Muller, Zool. Dan. Prod., No. 2413, 1776; 
Entomost., 114, t. 19, f. 1-3. 
— Latreille, Hist. Nat. Crust., iv, 269. 
— Bose, Man, Hist. Nat. Crust., ii, 259. 
— Baird, Mag. Zool. and Bot., i, 328, t. 9, f. 15-22. 
Monoctjlus chelieer, Manuel, Enc. meth., vii, 721, t. 264, f. 32-34. 
— Gmelin, Linn. Syst. Nat., edit. 13th, i, 2998, 
No. 21. 
Cyclops Johnstoni, Baird, Trans. Berw. Nat. Club, i. 97, t. 2, f. 4, 1835. 
Cyclops armatus, Tilesius, Mem. Acad. Imp. St. Petersb., v, 366, 
t. 8, f. 7, 8. 
Arpacticus chelieer, Baird, Trans. Berw. Nat. Club, ii, 154, 1845. 
Nauplius chelifer, Philippi, Wiegm . and Erichs. Archiv, 1843, p.69. 
* From ap7ra%, rapacious. 
