10 BRITISH COPEPODA. 



minutus, Plate XLIV, fig. 3 ; Eobertsonia tennis, Plate 

 XLI, fig. 3) ; the apex is, however, often strongly 

 clawed (Longipedia, Plate XXXIV, fig. 2 ; Euterpe, 

 Plate XL, fig. 2 ; Tachidius, Plate XXXVII, fig. 3, 

 &c.), and very frequently the two or three joints at the 

 proximal side of the claw are coalescent and greatly 

 enlarged, forming a pyriform or subglobose swelling 

 for the reception of strong muscular bands ; examples 

 of this structure are seen in the genera Tachidius 

 (Plate XXXVII, fig. 3), Harpacticus (Plate LXIV, 

 figs. 2, 13), Jonesiella (Plate XL VIII, fig. 3), and in 

 many others. The spinous and setose armature of the 

 antennae is, as a general rule, more profuse in the 

 males of all families ; a good illustration of this cha- 

 racter is seen in the case of Longipedia (Plate XXXIV, 

 figs. 2, 3). In Pcecilostoma and Siphonostoma the 

 sexual distinctions of the anterior antennas are not 

 strongly marked, consisting chiefly of imperfect hinge- 

 ments or contractions of the articulating surfaces 

 between various joints of the male organ. 



The posterior or second pair of antennce are generally 

 much smaller than the anterior pair, and consist in 

 most cases of two branches ; they seem to be used 

 both as swimming and prehensile organs, and in para- 

 sitic and semi-parasitic species are specialized for 

 prehension much more decidedly than the anterior 

 pair. The main branch consists usually of three or 

 four joints, to the basal or second joint of which is 

 attached a " secondary" or " inner" branch of smaller 

 size, and composed of one or several joints. This 

 branch is in some cases altogether absent ; in others 



