532 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv.ii. 



FAMILY CALIGID.E. 



Carapace broad and usually compressed. Cephalothorax incom- 

 pletely segmented, the free thoracic segments often partially over- 

 lapped or hidden by dorsal plates. Anterior antenna? short, club- 

 shaped, with two or three free joints, their basal segments anchylosed 

 with the anterior border of the carapace. Posterior antenna? in the 

 form of a simple hooked claw, not extending beyond the carapace. 

 Mouth in the form of a more or less elongated suctorial beak, formed 

 out of the upper and under lips and inclosing the toothed mandibles. 

 Maxilla? free, both pairs rudimentary, the first pair sometimes lacking. 

 Maxillipeds also free and in the form of hooked claws, the first pair 

 weak, the second much stronger and used for prehension. First four 

 pairs of thoracic legs usuall\ T biramose, but the first and fourth pairs 

 frequently uniramose; the fifth pair rudimentary and often invisible 

 dorsally or entirety lacking. Two simple eyes fused on the median 

 line, often lacking. Generative organs paired in both sexes; females 

 with two cord-like egg tubes, usually quite long; eggs in a single row. 

 Male usually smaller than the female and both sexes permanent para- 

 sites upon fish. 



1. Three anterior segments of thorax fused with the head; fourth and genital seg- 

 ments free 2. 



1. Two anterior thoracic segments fused with the head; third, fourth, and genital 



segments free - Subfamily Treeing. 



1. First thoracic segment only fused with the head, the others free; one or more of 



them with paired dorsal plates; all four pairs of legs biramose 3. 



2. Fourth segment without dorsal plates or any appendages except the fourth 



legs Subfamily Caligin^e. 



2. Fourth segment with a pair of dorsal plates which usually overlap the genital 



segment Subfamily Euryphorin^e. 



3. Frontal plates distinct; egg cases visible their entire length. 



Subfamily Pandarin^e. 



3. Frontal plates fused with the carapace; egg cases convoluted, entirely hidden. 

 Subfamily Cecropin^:. 



The genera belonging to the Caligina? are discussed in the present 

 paper; those belonging to the other subfamilies are left for subsequent 

 papers. 



Subfamily CALIGINJE. 



Carapace broad and always flattened dorso-ventrally; free thorax 

 segment without plates or appendages of any sort except the fourth 

 pair of legs. Genital segment enlarged, but usually smaller than the 

 carapace; never much larger except in the genus Echetus. First and 

 fourth thoracic legs uniramose, second and third biramose; fifth pair 

 rudimentary but often visible as a pair of small papilla? at the posterior 

 corners of the genital segment. Adults active, most of the females as 

 well as the males capable of swimming about freely. 



