332 PROCEEDINGS OF THE NATTONAL MVSEVM. vol. xxxrii. 



The mouth-tube is short and broad, with a bluntly rounded tip. 



First maxillse are present in the form of short claws near the margin 

 of tlie carapace ; the second maxillse are in tlie form of simple, slender, 

 and acuminate spines; the furca is biramose; the first and fourth 

 legs are uniramose, while the rami of the second and third pairs have 

 peculiar patterns of the joints, easily recognized after a little experi- 

 ence. 



In 'the Euryphorinae the sexes are also similar, the male always 

 smaller, more slender, and more active than the adult female. The 

 young females, however, are still as active as the males, since they are 

 unhindered by either egg strings or dorsal thorax plates. The pres- 

 ence of the latter in the adults helps to render them sluggish, and yet 

 there is no genus which actually becomes fixed like Echetus among the 

 Caliginse. 



For the other characters, the mouth tube is like that of the Calig- 

 inae, but there are no first maxillie nor any furca. The second max- 

 illae show a transition from simple pointed spines in Caligeria, through 

 a blunted biramose shape in Gloiopotes, into a flattened lamina in 

 Alehion. All the legs are usually biramose, the pattern of the rami 

 of the second and third pairs similar to that in the Caliginae. 



In the Pandarinae, on the contrary, the sexes are very dissimilar; 

 the females, even when young, carry so many dorsal plates on the 

 thorax and genital segment as to render them practically helpless. 

 They can swim but little and c{uickly become stationary upon their 

 host. But the males retain the powers of locomotion and can swim 

 or scuttle about over their host's body with as inuch freedom as those 

 of either of the preceding subfamilies. They have no trace of dorsal 

 plates, either on the thorax or genital segment ; the sex differences in 

 this subfamily, therefore, are the greatest anywhere shown in the 

 Caligidae. The mouth tube is long and pointed, and the mouth 

 parts are transformed into blade-like, smooth laminae, without spines 

 or setse, or they remain rudimentary. The swimming legs are also 

 characterized by the equality of the rami on the first pair and by a 

 general tendency toward degeneration in the females. This usually 

 affects only the last pair (Dinematura females), or the last two pairs 

 (Pandarus females), but sometimes affects them all (Demoleusiemales). 

 But whether degenerate or not their pattern is always totally dif- 

 ferent from that in the two preceding subfamilies. 



Finally in the Cecropinae we find the sexes again similar, but this 

 time they both carry dorsal plates on the thorax and genital seg- 

 ments which effectually prevent free swimming. And both sexes 

 become permanently fixed as soon as they have found lodgment 

 on their host's body. The mouth tube is not as long as in the 

 Pandarinae, but is fully as pointed, while the maxillte remain lami- 

 nate and are much larger proportionally than in any preceding sub- 



