LIGTA OCEANICA. 445 



pi. xiii. f. 1. KisfAHAN, Nat. Hist. Kev. iv. 



279, pi. XX. f. 7-10. GossE, Man. Mar. 



Zool. i. fig. 241. 

 Oniscus aquaticus. Bastbr, Opusc. Subs. ii. t. 13, f. 4. 



(Var.) Ligia scopulorum. Leach, Edinb. Enc. vii. p. 406. Linn. Trans. 



xi. p. 374. 



This is the largest British species in the family, from 

 the rest of which it also differs hy being found under 

 stones, &;c., in damp places on the shores of the ocean. It 

 has the upper surface of the body slightly rugose, being 

 covered with depressed granulations. The first segment 

 of the body has a deep transverse impression immediately 

 behind the head. The segments of the body have the 

 lateral margins thickened, curved, and terminating behind 

 in a rather sharp angle. The outer antennae are about 

 two-thirds of the length of the entire animal ; they are 

 robust, with the fourth and fifth joints much larger than 

 all the rest. The flagellum differs in the number of 

 articuli, probably on account of the difference in the 

 ages of the different individuals. The upper lip is entire, 

 and rounded at its free anterior margin. The lower lip, 

 on the contrary, is very deeply incised in the middle, 

 with the interior angles of the incision setose. The 

 mandibles are strong, armed with two compound teeth, 

 and with a strong incurved molar plate. In fig. d' the 

 mandible is seen laterally, the inner tooth and plate not 

 being visible from being on the same plane as the upper 

 tooth. The inner maxillae are formed of two terminal 

 lobes, of which the outer is terminated by several strong- 

 straight bristles, whilst the inner is shorter, and armed 

 with three deflexed setose bristles. The outer maxillae 

 have the two terminal divisions formed into two short 

 joints, with two or three strong short bristles on the out- 

 side of the penultimate joint. The preceding portion 

 has its inner apical angle produced into a setose fleshy 

 lobe. 



