ISOPODS OF NORTH AMERICA. 



235 



of antennae are composed of eleven articles, the last three being ver}^ 

 minute. The articles of both j)airs of antennae are greatly dilated and 

 tiattened. The second antenna' extend to the posterior margin of the 

 head. The maxillipeds have a palp of two articles. The palp of the 



Fig. 237 



-CERATOTHOA I.Ml'KES.SA. (I. MaXILLIPED OF FEMALE. X 21i. I), SECOND MAXILLA. X 27^. 



e, First maxilla, x 51|. d, Palp of mandible, x 27}. 



mandibles is ver}'^ large and conspicuous and is composed of three 

 articles. The second or posterior maxillae are very large and con- 

 spicuous, are bilobed at the tip, both lobes being furnished with small 

 hooks. 



The iirst four seguients of the thorax are large and about equal in 

 length; the tifth segment is half as long as any of the four preceding- 

 segments; the sixth and seventh segments are ver\' short in the 

 median dorsal line and each is about one-half as long as the fifth 

 segment. The first thoracic segment has the antero-lateral expansion 



b 



Fig. 238. — Ceratothoa impress.^ i, after Schicedte and Meinert). a, Yoi'ng of the second 

 stage, b. Young of the third sta(;e. c, Yox'ng of the first stage. (Enl.^rged.) 



produced in a carinated process, produced outward and forward and 

 terminating acutel}' a little anterior to the antero-lateral expansion of 

 the segment. The epimera are distinct!}^ separated on all the follow- 

 ing six segments. In the second segment they are directed forward 



