COPEPODA 



BRANCHIURA. 



411 



J? 



biramous and many-jointed swimming feet. The abdomen is 

 represented by a broad two-lobed caudal fin. 



The Branchiura though actively swimming animals are para- 

 sitic on marine and freshwater fish. They are often placed near 

 the Caligidae, but though they certainly resemble this group in 

 the general form of the body they differ from them and from 

 the Eucopepoda in several essential particulars. 



They have an oval flattened shape enabling them to adhere 

 closely to the bodies of 

 their hosts. The region 

 bearing the first pair of 

 swimming feet is fused with 

 the anterior part of the body 

 forming a cephalo thorax. 

 The abdomen is represented 

 by the short un jointed 

 bilobed tail fin, in the notch 

 at the end of which the 

 short caudal furca is found 

 (Fig. 267). Both pairs of Sj\ 

 antennae are s^mall. The 

 anterior is three- jointed and 

 carries a hook and the 

 posterior, though large and 

 biramous in the larva, is 

 simple in the adult. A 

 large suctorial tube projects 

 from about the mouth, and 



in if ttrp pnnppnlprl finplv 



in it are concealed nnely 



serrated mandibles and the 



first maxillae which, unlike 



those of the parasitic Eucopepods, are styliform.* A little 



anterior to this proboscis there is inserted a long cylindrical 



tube, terminating in a retractile styliform spine, which serves 



as a sting (Wilson). It is, however, not present in Dolops. 



species of Argulus. . . . Ibid. vol. 27 (1904) p. 627. Thiele J. Beit, z. 

 Morphologie d. Argulidae. Mitth. aus dem Zool. Mus. Berlin. Bd. 2. 

 Hft, 4(1904). 



* Thiele. however (I.e.), considers that only mandibles are contained in 

 the suctorial tube. He regards the appendages here named second maxillae 

 and maxillipeds as the two pairs of maxillae a result with which the posi- 

 tion of the opening of the shell gland would be in harmony. 



T 



267 ._ Youngle Argulm foliaceus (from 



Claus). A' Anterior antennae; D intestine ; 



Kf . / liaxilliped . R rostrum; Sf swim ming 

 feet : s <> sucker and second maxilla ; st s 



T testes. 



