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species have the distinct negative character of wanting trunk-legs and caudal stylets in both 
sexes, for as there are species which, though wanting these organs in one sex, not in the 
other, or through the male having trunk-legs, but no caudal stylets, form a transition to the 
species in which both sexes possess trunk-legs and caudal stylets, one cannot very well set 
apart the first mentioned species as a separate genus. Jf I can find no leading principle 
to guide me in carrying out the division of a large genus, the elements of which seem to be 

heterogeneous, and if I am not obliged to undertake a division in order to bring about an 
equivalence with previously established acceptable genera, I prefer putting off the division till 
the discovery of new forms has thrown new light on the question. If I had had to subdivide 
Spheronella, the result would have been, not two or three, but six or seven genera (some of 
which would have consisted of only one or a couple of species), in order to establish a pretty 
correct equivalence, but these new genera would not have been tolerably equivalent with 
such types as Homoeoscelis, Mysidion ete. 
ec. Characters of the Family. 
An examination of the genera will show very clearly that, in spite of several diffe- 
rences, they are all very closely related and belong to the same family. We will here 
attempt to give a summary of all its more important characters, some of which separate it 
from one, some from another, of the rather numerous families of parasitic Copepoda, for it 
would be impossible to give a condensed characteristique with merely exclusive features, our 
knowledge of several points in the organisation and development of other families being 
too defective. 
The adult Females ave ovate or sub-globular. The head occupies only a smaller or a 
minute part of the greatly swollen, unsegmented body; the abdomen is comparatively rather small 
and unsegmented, or mostly altogether wanting. Antennul 1-3-jointed; antennze small or wan- 
ting; rostrum good-sized, comparatively stout with cup- or funnel-shaped mouth provided with a 
border formed by a membrane which is interrupted only in front and supported outside by free 
hairs; maxillule consisting of a basal part almost entirely fused with the rostrum, and of two 
or three usually setiform branches; maxillze short and powerful prehensile limbs consisting of a 
stout basal joint and a slender, 1- or 2-jointed, somewhat claw-shaped, distal part; maxillipeds 
rarely wanting, mostly appearing as good-sized grasping appendages, consisting of a long, rather 
stout basal joint and a shorter, slender, 2- or 3-jointed distal part. We often find two pairs of 
rather small or minute trunk-legs, each of which consists of one single joint or sometimes of a 
peduncle with one or two unjointed branches; the legs are wanting in not a few species. Caudal 
stylets present or wanting. Some species, at least, can hinge themselves by an adhesive plate 
or a frontal thread. Spermatophores (found in many species) consisting of a globular or oval 
vesicle on a rather long thread-shaped stalk. 
ities 
