270 



BULLETIN '^i, UNITED STATES NATIONAL MUSEUM. 



iirst; the lifth article is about as long- as tlie fourth. The tiagellum is 



composed of two or three indistinctly defined articles. The maxilli-' 



peds have a palp of Hve articles. The ptilp of 

 the mandi))Ies is composed of three articles. 



The first seg- 

 ment of the tho- 

 rax is longer than 

 an}" of those fol- 

 lowing, which are 

 subequal; it is al- 

 most twice aslong. 

 Epimera are dis- 

 tinctly separated 

 on all the segments 

 with the excep- 

 tion of the first. 

 The abdomen is composed of six distinct 



segments. The tirst five are short and su]>- 



equal. The sixth or terminal segment has 



the posterior margin widely rounded. The 



uropoda are laterally placed. The outer 



branch is small and rudimentary. The inner branch reaches th( 



extremity of the abdomen. 

 All the legs are ambulatory. 



Fig. 280.— Limnoria lignorum 

 (After Harger). a. First an- 

 tenna. x25. &, Second antenna. 

 X 25. c, Maxilliped. X 25. d, 

 Second maxilla, x 25. e. First 

 maxilla. X 25. e', Distal end of 

 first maxilla. X 66. /, Mandi- 

 ble. X 25. 



Fig. 281.— Limnoria lignorum 

 (After Harger). a. Last seg- 

 ment OF abdomen with uropoda. 

 X 10. b, Uropod. X 30. c. First 

 pair of pleopoda. X 20. d, Sec- 

 ond pleopod of male. X 20. 



Family XL SPH.EROMID^E. 



Body short, oval, convex. Head transverse. 



First and second pairs of antenna? multiarticulate with evident dis- 

 tinction into peduncle and fiagellum. jNlandibles with palps. Anterior 

 segments of abdomen united into a single segment, which, with the 

 large terminal segment, forms a biarticulate al)domen. 



Uropoda lateral, forming, with the terminal abdominal segment, a 

 caudal fan. Outer branch of uropoda, when present, movable. Inner 

 l)ranch fixed, inunovable. 



Epimera luiited with the thoracic segments. 



ANALYTIC.VL KKY TO THE CEXKRA OF THE F.AMII.Y WPH.EROMID^. 



a. Outer liranch of the uropo<la entirely wanting Genns Ancinus Milne Ed\var(l>i 



a^. Both l)ranches of the uropoda prei^ent. 



/'. Outer t)ranch of the uropoda .small, rudimentary ( ieiius Cassidmri, new genus 



//. Outer branch of the uropoda not rudimentary, 

 c. First and second pairs of legs subchelate in male; only first pair subc-helate 



in female Genus Tecticepa Richardson 



c'. Legs all ambulator}-. 



d. Outer branch of uropoda caiKiblc of folding under inner ))ranch; both 

 branches similar in shaiie and salient. 



