84 
The Males ave several or many times smaller than the females, oblong or sub-globular. 
The head forms a little more or a little less than half of the unsegmented body. Abdomen nearly 
as in the females. Antennule, antenne, rostrum, maxillule and maxillipeds nearly similar to 
those of the females. Frequently, though far from always, we find too pairs of trunk-legs, 
which are often good-sized and two-branched, with long terminal sete, but very rarely jointed. 
Caudal stylets frequent. They hinge themselves by a rather long, or very long frontal thread. 
Development. The eggs are deposed in one or two (rarely three) free, irregular 
lumps, or most frequently, in several (at least four or five) or many (up to twenty-eight) 
ovisacs, which, as a rule, are free, though sometimes hinged on the lips of the genital 
apertures. The Nauplius stage is passed through in the egg; the forthcoming larva is in 
the first Cyclops stage, with an oval, somewhat depressed cephalothorax, which is divided 
far back by one articulation, and a 3-jointed abdomen with caudal stylets, each with a very 
long terminal seta. Cephalothorax with 2- or 3-jointed antennule, provided with a very long 
olfactory seta, 2-, 3. or 4-jointed antenne; rostrum in the main as in the adults, maxillule with 
— as a rule — indistinct basal part and (one) two, three or four setiform branches; 2- or 3- 
jointed maxille and 4-jointed maxillipeds, both pairs chiefly constructed as in the adults; 
finally, two pairs of natatory legs, each with two 1-jointed branches. Out of this larva, which 
hinges itself by a frontal adhesive plate, the males not unfrequently, the females sometimes, 
appear directly, without passing through any intermediate stage. In other species the larva 
develops into a pupa, out of which the male proceeds. In most species the same meta- 
morphosis is gone through by the female; in one case the female passes through at least 
one additional intermediate stage. Where a pupa is found, it is always hinged; besides it 
is nearly always provided with a mouth and increases considerably in size. After hatching 
the males grow comparatively rather little, and the same is the case with the head of the 
females, whereas the trunk of this sex swells excessively. 
A distinctive mark of this family is the above (p. 27—28) described mouth, which 
appears, not only in the female and in the male, but — as far as its most important features 
are concerned — also in the larva, and nearly always in the pupa. 
d. Place of the Family in the System. 
During the last thirty years and more, the parasitic Copepoda have been very little 
studied, and not a single really leading work has appeared about this subject. Several 
authors have established a series of genera, some of which might easily be ranged in the 
old families, while others stand rather isolated. Some smaller families have also been 
instituted. If, however, we try to get a general view of our present knowledge. we find 
that several families are badly defined, and others so imperfectly known, that we cannot 
form a definite opinion of their place in the system: whether they belong to one 
of the established families, or must be taken as types of new families. The reasons 
