So 



THE CRUSTACEA 



particles. In the Podoplea the setae are generally much reduced, 

 and stout spines are developed on the endites. In many cases, 

 especially in parasites, the armature is reduced to a single terminal 

 claw-like spine and the limb is exclusively a clinging organ. 



In the parasitic family Lernaeopodidae, a very remarkable 

 apparatus of attachment is formed by two appendages which unite 

 to form a sucker-like organ of complicated structure (Fig. 45, B). 

 In some cases, when the appendages are short, they coalesce com- 

 pletely to the base, but in other cases they have the form of 



B. 



mxp. 



FIG. 45. 



Achtheres percarum (Lernaeopodidae). A, larva in first Copepodid stage, dorsal view. B, 

 adult female, ventral view, x 25. a', antennule ; ft", antenna ; c.gl, cement gland opening into 

 oviduct ; e, median eye ; /, caudal furca ; f.gl, frontal cement gland ; mx", maxilla ; mxp, maxil- 

 liped ; o, opening of oviduct; ovd, oviduct distended with eggs ; up, openings of spermathecae. 

 (After Claus, slightly modified.) 



long arms, united only at the tip. These appendages have been 

 regarded sometimes as the " first maxillipeds " (maxillae) and 

 sometimes as the " second maxillipeds " (here called maxillipeds). 

 The fact that a pair of glands, identified as the maxillary 

 (excretory) glands, open at their base, seems to show that the 

 former interpretation is the correct one. An apical coalescence 

 of paired appendages is not known to occur in any other 

 Arthropods. 



The maxilliped (first thoracic limb) is always uniramous, and is 

 generally more elongated than the maxilla (Fig. 41, D). It consists 



