364 
Dr. Leach’s Arrangement of the Crustacea, 4^c. 
Spec. 1. Larunda Ceti. ‘ 
Oniscus Ceti. Lin7i. Syst. Nat. i. 1060. 
Squille cle la Baleine. De Geer, Mim. stir les Ins. vii. pi. 42. f.(S. J. 
Pycnogonum Ceti. Fabr. Suppl. Ent. Syst. 6'70. 
Cjamus Ceti. Latr. Gen. Crust, et Ins. i. 60. 
Panope Ceti. Leach, Edin. Encycl. vii. 404. 
Habitat in balaenis (etiam in scombris, Latreille). 
D I VIS I o II. 
Corpj/s segraentis omnibus baud pedigeris ; segmentum ultirnum 
caud^ maximum. A titetma Gliformes, mediae brevissiiufe, ex- 
teriores ad corporis dimidium longitudinis et ultra. Unmies 
validi. 
Gen. 18. Idotea. 
Antenna exteriores dimidium aut minus corporis longitudinis 
aequantes, articulis tertio quartoque aequalibus. Corpus ovatum. 
Spec. 1. Idotea Entomon. 
I. corpore elongato-ovato, caud^ apice tridentatd : dente inter- 
medio majore, antennis dimidium corporis longitudinem fere 
aequantibus. 
Oniscus Entomon. Lmn. Syst. Nat. i. 1060. 
Penn. Btdt. Zool. iv. pi. 18. fig. 5. 
Habitat in rnari Britannico passim inter fucos. 
Color cinereus, fusco-punctatissimus, saepe cremore maculatus. 
This species, which is very common on all our rocky coasts, va- 
ries much in the form of the extremity of the tail, often occurring 
without the lateral teeth, which is ever the case (as far as I have 
examined) in younger specimens. Oniscus marinus of Pennant, 
plate xviii. fig. S, appears to be the variety above mentioned. 
Length one inch and a quarter. 
Spec. 2. 
