72 H. J. HANSEN. 
describing in all only two new species as types for new 
interesting genera and adding some remarks on an old quite 
imperfectly known form. For various reasons I cancel two 
genera; some of those still maintained are of slight value, 
but I did not think it proper to withdraw more than absolutely 
necessary. I must establish seven new genera, six of which 
are types of importance. Most of the species hitherto estab- 
lished are enumerated, but I did not wish to mention every 
species of Spheroma and Cymodoce scattered in the vast 
literature. The enumeration is undertaken in order to refer 
the species to the genera to which they really belong; a 
perusal of my notes on such generaas Spheroma,Cymodoce 
Newsa, Cassidina will convey an idea of the extreme con- 
fusion as to classification in nearly the whole literature. 
Rather frequently the descriptions—especially when accom- 
panied with figures—of species unknown to me are sufficient 
for reference, but in several cases this must be doubtful; in 
too numerous cases—especially when the species in question 
differ as to shape of the proximal joints of the antennule or 
of the end of abdomen from the type of that genus to which 
they have been referred in the literature—is it unfortunately 
impossible to say anything on the real relationship, because 
figures and especially descriptions are too incomplete. 
Only in very few cases titles of papers are given; if such 
references to literature had been inserted everywhere in the 
systematic “notes” the bulk of this paper would have been 
very much increased. The synonymy of several species of 
Spheroma and Cymodoce is extremely intricate, and is 
omitted. It is scarcely necessary to say anything on my 
treatment of characters and classification; every student who 
will take the trouble to read the three following chapters and 
look through the diagnoses of sub-families, groups, sections, 
and genera may easily perceive the principles of classification. 
Yet it may be added that in Isopoda—and in other orders of 
Arthropoda—lI dislike a modern tendency manifesting itself 
in splitting up orders into a very large number of families ; 
wishing to procure a view of the relationships, I collected at 
