84 



Hie Males are several or marry 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. Antennulae, antennae, rostrum, maxillulae 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 setse, 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 antennulae, provided with a very long 

 olfactory seta, 2-, 3 or 4-jointed antennae; rostrum in the main as in the adults, maxillulae with 

 — as a rule — indistinct basal part and (one) two, three or four setiform branches ; 2- or 3- 

 jointed maxillae 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 



