CRUSTACEANS. 229 



larger and two smaller anteniiEe^ besides two eyes^ also situated in front. 

 The last segment terminates in an obtuse projection, and covers some 

 follicles at the extremity below. Of the four antennas the two external 

 are half an inch long, rather stout, and pointed, consisting of five articu- 

 lations ; an internal pair, nearly in the middle between them, are shorter. 

 There are fourteen limbs disposed as seven pair, each provided with a 

 recurving claw ; fig. 8, a, limb ; fig. 8, b. Colour dingy yellow, or 

 brownish-yellow, with three or four white specks down the centre of the 

 back ; or it is altogether of variegated, and some are mottled. 



This creature feeds voraciously, seizing and carrying off prey in its 

 fore limbs. It also devours the smaller Crustacea and mussel very readily. 

 It swims swiftly, and when at rest it generally clings to some substance 

 admitting of its position supine. 



Exuviation ensues at difierent seasons ; the shell has been always 

 cast in two portions. Perhaps the limbs are arranged in two divisions, 

 separated by a slight excess of the usual interval. 



The variegated specimens are beautiful animals, especially when first 

 appearing in their new shells. 



I have been induced to conclude that the number of segments is 

 only seven, though nine may appear from some delusion. 



Plate LXIII. 



Fig. 5. Oniscus {Ideotea) haltUcus. 



6. Last segment of the same, enlarged. 



7. Cast shell, anterior portion, enlarged. 



8. Variegated specimen ; fig. 8, a, limb ; fig. 8, i, antennae. 



9. Greenish specimen. 



§ 5. Oniscus (Ideotea) entomon. — Plate LXIII. fig. 10, a. 



Several authors name this subject, but few seem to have had it 

 alive. The Baron de Geer, who treats at large of various crustaceous 

 animals, observes, that, never having seen a living specimen, he can say 

 nothing of its habits ; Tom. 7, p. 523. 



