638 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



Family XXVI. ARMADILLIDIDyE.« 



Body convex, contractile into a perfect ball. 



Pleural parts of the head fused. 



Front of head truncate, marginate; ante ro- lateral lobes distinct; 

 median lobe wanting; epistome vertical; clypeus perpendicular. 



First pair of antennae small, inconspicuous; flagellum composed of 

 two or three articles. Second pair of antennse generally short, distant; 

 antennal foramina small. 



Abdomen not abruptly narrower than thorax; terminal segment 

 short and broad. 



Opercular plates of the first two pairs of pleopoda or of all five 

 pairs provided with tracheae. 



Uropoda short, flattened, not extending beyond the extremity of the 

 terminal abdominal segment or the lateral parts of theprecedingsegment. 



The young, when hatched, have all seven segments of the thorax 

 present. 



Mouth parts as in the Oniscid^e. Legs comparatively short. 



ANALYTICAL KEY TO THE GENERA OF AKMADILLIDID^. 



a. Outer branch of the uropoda very small or minute. Basal joint large. 

 b. Flagellum of external antennte with two or three joints. 

 c. Flagellum with two joints. 

 (/. Last abdominal segment subtetragonal, base wider than apex, more or less 

 contracted in the middle. External branch of the uropoda inserted in the 

 middle of the internal lateral margin of the basal joint. Coxopodites of 

 first and usually of the second segments distinct from the segments 



( underside) Genus Oubnris Brandt. 



d\ Last abdominal segment trapezoidal or sul)cordiform* narrower at its 

 truncate apex. External branch of the uropoda inserted in the inner 

 post-lateral angle of the basal joint. Coxopodites of the first and second 



segments distinct (underside) Genus PseudarmadiUo Saussure. 



c^. Flagellum with three joints. Coxopodites of the first segment usually distinct 

 on the underside. Ternnnal segment of body very short, rounded or pos- 

 teriorly triangular. External branch of the uropoda inserted in the inner 

 post-lateral angle of the quadrangular basal joint, and extending down- 

 ward. iLner branch reaches much beyond the terminal segment of the 



body Genus SphaToniscus Gerstsecker. 



I/. Flagellum of external antennae with a single joint only. Coxopodite distinct on 

 the first segment (underside). External branch of the uropoda inserted at 



inner post-lateral angle of the basal joint Genus Haplnriiindillo Dollfus. 



a\ Outer l)ranch of the uropoda large, flattened, lamellar, inserted at the apex of the 

 basal joint. 

 h. Terminal abdominal segment triangular in shape. Inner branch of uropoda 

 conical. All seven pairs of legs present. Seventh thoracic segment with 



lateral parts well developed Genus ArmadilUdimn Brandt. 



//. Terminal abdominal segment quadrangular in shape. Inner branch of the 

 uropoda flattened, rounded. Only six pairs of legs present. Lateral parts of 

 seventh segment of thorax not developed Genus Uropodias Richardson. 



^'See Budde-Lund for characters of family. Crust. Tsop. Terrestria, 1885, pp. 14-15, 

 and G. O. Sars, Crust, of Norway, II, 1899, pp. 187-188. 



