1310 



CRUSTACEA. 



The Poecilopoda thus form a continuous line downward from the 

 higher Cyclopoidea. The line comes more especially through the Cory- 

 ceeidae, and for the reason that these are the Cyclopoid species in 

 which the posterior antennae are prehensile. There are a few of the 

 sucking Ergasiloidea, in which these antennae are without a prehensile 

 character. But in Ergasilus, the form is quite like that of Corycaeus 

 and Sapphirina ; and in nearly all the lower groups, the prehensile 

 structure is well developed, although under varied forms. These 

 organs are clinging organs throughout the greater part of this section 

 of suctorial Crustacea, and the principal organs of this character in a 

 large number of species. 



The three tribes of Poecilopoda are hence characterized as follows : 



I. Ergasiloidea.* — Cephalothorax annulatus, carapace non tectus.. 

 Truncus buccalis non mobilis, brevis, mandibulis interdum obso- 

 letis (?) . Pedes 8 postici bene natatorii ac in Cyclopoideis. Ova 

 externa in sacculos gesta. Corpus ssepius non depressum. 



II. CALiGOiDEA.f — Cephalothorax si ve annulatus sive carapace tectus. 

 Truncus buccalis mobilis, mandibulis armatus. Pedes 8 postici 

 plus minusve natatorii, ssepe partim in laminis coaliti. Ova externa 

 in tubos duos longos uniseriatim gesta, tubis raro obsoletis. Corpus 

 ssepius valde depressum et peltatum. 



III. Lersleoidea. % — Cephalothorax vix annulatus. Corpus sive breve 

 et obesum sive elongate vermiforme. Pedes natatorii obsoleti. Ova 

 externa sive in sacculos aggregata sive tubos uniseriata. 



* Frgasiliens, Edw., Crust., iii. 476. 



f Includes the "Peltocephales" of Edwards, and his "DicJielestiens." 

 J Lerntides, Edw., Crust., iii. 488 ; Lemseoda and Penellina united of Burmeister, 

 Acta Ac. Caes. Leop., xvii. 270.; Lerneadss, Baird, Brit.. Entomost., 307. 



