214 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



flagellum is composed of seven articles. The first antennae extend to 

 the end of the peduncle of the second pair of antennas or to the pos- 

 terior margin of the head. The second pair of antennae have the tirst 

 two articles equal in length; the third and fourth are also subequal, 

 and each is about twice as long as the second; the fifth is one and a 

 half times longer than the fourth. The flagellum is composed of 

 twenty-five articles. The second antennae extend to the posterior 

 margin of the third thoracic segment. The frontal lamina is large, 

 conspicuous, rhomboid shaped, and ventrally placed. The maxilliped 

 has a palp of two articles. 



The first segment of the thorax is longer than any of the others. 

 The epimera are distinct from the segments with the exception of the 

 first. They are broad plates with the posterior extremities very acute. 

 The post-lateral angles of the first thoracic segment are also acute. 

 The abdomen is abruptl}" very much narrower than the thorax. All 

 six segments are distinct. The lateral parts are not 

 separated oil from the dorsal portion. The terminal 

 segment is large and triangular in shape, with the pos- 

 terior extremity acutely produced. The uropoda are 

 as long as the terminal segment of the abdomen. 

 The outer branch is wider but shorter than the inner 

 branch; it is more broadly rounded posteriorly than 

 the inner branch. The peduncle of the uropoda is not 

 produced at the inner angle. 



The first three pairs of legs are prehensile, the last 

 INFELIX. MAXIL- four pairs ambulatory. The tirst three pairs are not 

 furnished with spines. The fifth pair of legs is a little 

 longer than the fourth pair. The sixth and seventh pairs are equal in 

 length and extremely long, being very much longer than the fourth 

 and fifth pairs. 



Family IX. CYMOTHOID^. 



Antennae strongly reduced and without clear distinction between 

 peduncle and flagellum. All seven pairs of legs prehensile, terminat- 

 ing in strong hooked fingers. Pleopods not ciliated. Terminal seg- 

 ment and uropoda usually not ciliated. 



Maxillipeds with palp composed of two articles; terminal article 

 furnished with hooks. 



Mandibles with palps. 



First maxillae with masticatory lobe composed of a single tapering 

 article furnished with four spines at tip. 



Second maxillae bilobed at tip and furnished with numerous spines. 



Epimera distinct on all the segments with the exception of the first. 



Parasitic forms. 



