442 ONISCIDA. 
ISOPODA., ONISCIDAL. 
NORMALIA. 
Genus—LIGIA. (Fabricius.) 
Generic character. External antenne long, with a multi- 
articulate flagellum. Terminal pair of uropoda with the basal 
portion exserted backwards, truncated at its extremity, to 
which are affixed a pair of elongated cylindrical rami. 
Tur. head is small, its anterior margin forming a con- 
tinuous arched line with the sides of the first segment of 
the body. 
‘¢ When the head is looked down on from the front, we 
remark anteriorly, just beneath, but not attaining to the 
frontal line of the head, a broad plate extending over 
the entire forehead, and divided transversely by a raised 
ridge; its superior margin is also marked by a raised 
ridge. This superior ridge passes off on each side 
beneath the eyes, forming at least a third of the inferior 
border of the orbit. The external angle of the orbit, 
however, is formed not by this, but by the cephalic ring 
continued forward from behind, and terminating as a 
rounded knob just above the external antennez ; these 
arise in the angle between the inferior border of the 
frontal plate and the projecting lobes. The inferior 
border of the frontal plate is formed of two curves, 
convex upwards, one over the origin of each external 
antenna; the angle of their junction is truncate, sepa- 
rated by a short transverse suture from a small, narrow, 
somewhat quadrilateral plate, which bears the internal 
antenne, and is probably the remains of the second or 
internal antennary ring; the frontal plate itself repre- 
senting the external antennary or third ring of the typical 
crustacean. Beneath is a broad, well-marked plate, the 
epistome.”— Kinahan, op. cit. p. 264. 
