TERRESTRIAL ISOPODS COLLECTED IN COSTA RICA BY 

 J. F. TRISTAN, WITH DESCRIPTIONS OF A NEW GENUS 

 AND SPECIES. 



By Harriet Richardson, 



Collaborator, Division of Marine Invertebrates, U. S. National Museum. 



Among some isopods recently sent to the U. S. National Museum 

 from Costa Rica by Prof. J. F. Tristan were twelve specimens repre- 

 senting a species belonging to a new genus of Armadillididae. Two 

 previously known species were also found. 



Body oval, convex. 

 Eyes distinct, composite. 



Second antennae with a flagellum composed of two articles, the 

 second being twice as long as the first. 



Coxopodite of first thoracic segment extending the entire length of 

 the lateral margin, cleft posteriorly, and separated from the seg- 

 ment by a longitudinal furrow; there is also a slight furrow on the 

 dorsal surface of the segment close to the lateral margin. Coxopo- 

 dites are present on the second and third segments of the thorax on 

 the underside in the form of small, but conspicuous tooth-like 

 processes. 



Terminal abdominal segment triangular, with the apex acutely 

 produced. Basal article of the uropoda large, obliquely quadrangular; 

 inner branch about as long as the basal article; outer branch minute, 

 inserted about the middle of the dorsal surface of the basal article. 



This genus is close to Ethelum Budde-Lund, but differs in the 

 possession of distinct coxopodites on the second and third thoracic 

 segments, in the position of the outer branch of the uropoda, and in 

 the possession of only two plumose processes on the inner lobe of the 

 first maxillae. 



Genotype. — Coxopodias tristani, new species. 



COXOPODIAS, new genus, 



Proceedings U. S. National Museum, Vol. 39— No. 1775. 



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