34 BRITISH COPEPODA. 



of several joints. Mandibles strongly toothed at 

 the apex, palp (usually) two-branched. Maxillae 

 strong, and provided with a many-lobed palp. Foot- 

 jaws strongly developed : first pair very broad ; the 

 basal joints having on the inner margin wartlike 

 processes from which spring long ciliated bristles ; the 

 distal extremity divided into three short joints which 

 are thickly beset with strong and long ciliated setae : 

 second pair longer and more slender, basal portion 

 forming two long oval joints ; apical portion usually 

 4 6-jointed. First four pairs of feet 2-branched, the 

 outer branches always three-jointed. Fifth pair either 

 like the foregoing, or much modified, unlike on the 

 two sides, and in the male forming clasping organs ; 

 a heart is present. Eyes either median and stalked 

 or paired (lateral) and sessile ; in the latter case being 

 often coalescent and composed of several lenses. 

 Sexual organs in the female symmetrical, in the male 

 asymmetrical. Ovisac single ; borne in front of the 

 abdomen. 



This definition is framed so as to include the species 

 belonging to the two families Calanidae and Pontellida3 

 as described by Dr. Glaus. There being, as I think, 

 no sufficient ground for separating the latter as a 

 distinct family, I here follow Dana and Boeck in con- 

 sidering the whole as one family, comprising two sub- 

 families CalaninoB and Pontellince. The characters 

 which chiefly distinguish the two groups are those of 

 the eyes, footjaws, and anterior antennae, but Glaus 

 has pointed out that the genus Centropages exhibits a 

 transition as regards the eye, while Centropages , 



