256 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



mill. The post-lateral ang'les are rounded, and the posterior niaroin 



is slightly excavate in the middle. 



The iiropoda are as long as the 

 terminal abdominal segment. 

 The outer branch is slightly 

 shorter than the inner branch. 

 Both are equal in width, 

 and narrow, with extremities 

 rounded. 



The legs are all prehensile, 

 with short, stout, curved clac- 

 tyli. There is a high carina 

 on the basis of the last four 

 pairs, the carina increasing 

 gradual!}^ from the fourth to 

 the seventh pair, where it is 

 extremely higli." 



42. 



Genus LIVONECA 

 Leach'. 



Body sul^oval, more or less 

 twisted. 



Head most always deeply 

 immersed. First pair of an- 

 tennae widel}^ separated at the 

 base, rather compressed. 



Anterior margin of the first 

 thoracic segment widely sin- 

 uated in the middle, more or less sinuated or incised at the antero- 

 lateral angles. 



Abdomen very little immersed, continuous with thorax, not nar- 

 rower than thorax. 



Fig. •2t)4. — Cymothoa cestrum. o, Maxilliped. 

 6, Seventh leg. x 4^. c, First maxilla. 

 d, Second maxilla. x 15^. e, Mandible. 

 /, Palp op mandible, x 15^. 



X 15i. 

 X 15i. 

 x 15i. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS LIVONECA. 



a. Abdomen somewhat immersed in thorax, the sides of the first segment being 

 almost entirely covered by the seventh thoracic segment. 

 h. Head quadrate, but little broader at the base than at the anterior end. 



Linmeca panamensis Schitt^dfe and Meinert 



b^. Head triangular, nearly twice as broad at the base as at the anterior extremity. 



r. Head roundly truncate in form. Terminal segment of abdomen nearly twice 



as l)road as long Livoneca vulgaris Stimpson 



(•'. Plead narrowly rounded in front. Terminal segment of abdomen about as 



long as broad Livoneca caUfornica Schitx'dte and Meinert 



a^. Abdomen not immersed in thorax, the sides of the first segment free. 



« For complete description of this form, the male and female and the young of 

 the first and second stages, see Schioedte and Meinert, Nat. Tidsskr. (3), XIV, 

 188:5-84, pp. 271-278 



