1348 



CRUSTACEA. 



are named the second pair in this section, because both pairs are 

 actually feet, and not maxillae or maxillipeds ; and because the trans- 

 fer of appendages from the mouth to the foot-series, marks a very im- 

 portant step in the gradation of the species, distinguishing the Cali- 

 goidea from the Cyclopoidea. 



In the lowest Lernaeoids, the only appendages present appear to be 

 homologues of the second antennae. 



The following is a synopsis of the subfamilies and genera of Cali- 

 goidea. The family Argulidae contains, as far as known, but a single 

 genus. The Caligidae embrace three types of structure : one, Cali- 

 GINje, with the trunk-mouth ovoid and obtuse, and the maxillae distant 

 from it, with a stout spiniform base, and the rest of the organ obso- 

 lete or nearly so; a second, Pandarinje, having the trunk slender 

 and tapering, with the maxillae small lamellar and appressed to the 

 sides of the trunk, and the external oviferous tubes straight; a third 

 (the Cecropinae), like the second in its mouth and maxillae, but having 

 the oviferous tubes convoluted beneath the body. 



Fam. I. ARGULIDAE. 



Gr. ArgULUS, Miiller. 



Fam. II. CALIGID^. 



Subfam. 1. CALIGIN^E.— Truncus buccalis ovoideus, paulo oblongus, 

 apertura oris inferiore. Maxillae ab ore remotae, brevissiinae, 

 crassae. Tubi ovigeri externi recti. Antennae anticae 2-articulatae. 



G-. 1. Caligus, Miiller. — Cephalothorax segmento postico unico transverse* et non alato 

 instructus. Pedes natatorii lmi simplicissimi ; 2di biramei ; 3tii late lannnati 

 et coaliti; 4ti simplicissimi subteretes et elongati et non natatorii, seta digiti- 

 formi longa 2-3 aliis brevioribus confecti. Frons discis duobus suctatoriis infra 

 instructus. 



G-. 2. Lepeophtheirus, Nordmann. — Caligo cephalothorace pedibusque similis. 

 Frons discis suctatoriis non instructus. 



Gr. 3. Caligeria, Dana. — Lepeophtheiro similis. Segmentum cephalothoracis 2dum 

 utrinque alatum. Pedes duo postici biramei, setis brevibus, non natatorhs. 



G. 4. Calistes, Dana. — Lepeophtheiro cephalothorace discisque nullis frontis similis. 

 Pedes duo postici biramei, subnatatorii, setis plumosis instructi. Segmentum 

 cephalothoracis posticum non alatum. 



