18 C. BOVALLIUS: NEW ISOPODA. II. 
Syscenus Lilljeborgii is to be distinguished from S. 
infelix: by the three first pairs of pereiopoda being smooth, 
not armed with spines on the palmar margins of the tibia, 
carpus and metacarpus; by the large quadrangular épimerals 
of the second and third segments, being much longer than 
those of the two following segments; by the linear pleon, 
not increasing in breadth backwards; by the long urus, being 
much longer than broad (20:14). Also in the form of the 
head and in the antenne there are some differences. 
