674 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



Second pair of antennae strong and elongated; flagellum multi- 

 articulate. 



Palp of maxillipeds with joints rather expanded; epignath rounded. 



Uropoda with the basal article not produced inside at the post-lateral 

 angle; branches subequal. each tipped with a single terminal spine. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS LIGYDA. 



a. Uropoda long, equal to two-thirds the length of the body or longer. External 

 antenna 1 long, extending the entire length of the thorax or longer. 



b. First pair of legs similar to the others in the male Ligyda olfersii (Brandt) 



b'. First pair of legs in the male differing from the others. 



c. Propodus of first pair of legs armed with a long narrow process at the distal 



end. Peduncle of second antennae extends to posterior margin of the third 



thoracic segment. The second antennae extend in the male to the end of 



the body or a little beyond. Body loosely articulated . . Ligyda exotica ( Roux ) 



c f . Propodus of first pair of legs in male unarmed. Merus and carpus in the first 



pair of legs in the male furnished with a row of bristles or stiff hairs. 



Peduncle of second antennae extends to the posterior margin of the second 



thoracic segment. Second antennae extend in the male to the end of the 



thorax. Body compact Ligyda baudiniana (Milne Edwards) 



of . Uropoda not equal to two-thirds the length of the body. 



b. Uropoda equal to half the length of the body. Terminal segment of the body 



pointed in the middle Ligyda occidentalis (Dana) 



b f . Uropoda not equal to half the length of the body. Terminal segment rounded 



in the middle. 



c. Branches of the uropoda twice as long as the peduncle. Uropoda equal to one- 

 eighth the length of the entire body from the tip of the terminal abdominal 

 segment. Lateral parts of the third, fourth, and fifth segments of the abdo- 

 men with distinct carinae Ligyda pallasi (Brandt) 



c'. Branches of the uropoda four times as long as the peduncle. Uropoda equal to 

 one-fourth the entire length of the body from the tip of the abdomen. 

 Lateral parts of the third, fourth, and fifth segments of the abdomen with- 

 out distinct carinae Ligyda oceanica (Linnaeus) 



LIGYDA OLFERSII (Brandt). 



Ligia olfersii BRANDT, Bull. Soc. Imp. Naturalistes de Moscou, ^ 7 I, 1833, p. 11. 

 BUDDE-LUND, Crust. Isop. Terrestria, 1885, p. 268. RICHARDSON, Proc. U. S. 

 Nat. Mus., XXIII, 1901, p. 575. 



Localities. Key West and Puntarasa, Florida; St. Thomas; Brazil. 



Bodj 7 oblong-ovate, a little more than twice as long as wide, 7 mm. : 

 15 mm. Length of uropoda, from tip of terminal segment, 8 mm. 

 Entire length of body with uropoda 23 mm. 



Head twice as wide as long, 2 mm. : -i mm. Anterior margin widely 

 rounded. Eyes composite, narrow, oblong, twice as long as wide, sit- 

 uated on the lateral margins and extending along the anterior margin, 

 being separated in front by a distance a little less than the length of 

 one eye. First pair of antennae inconspicuous and rudimentary, com- 

 posed of two subequal articles and a minute terminal one and extend- 

 ing only to the end of the first article of the second pair of antennae. 



