16 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



onymized the genus Scaeother Gorham, 1888, with Haematochiton 

 Gorham, 1888. Boyle (1956) synonymized H. bisculptum Casey, 1916, 

 with H. elateroides Gorham, 1888, and synonymized the following two 

 forms under H. carbonarius (Gorham, 1888), new combination: 

 Scaoether carbonarius Gorham, 1888 (1887-1899), and Scaoether 

 opacus Schaeffer, 1915. Boyle (1956) created a key for the two 

 species then recognized: H. elateroides Gorham, 1888, and H. car- 

 bonarius (Gorham). Alvarenga in 1965 stated that the type-species 

 is Haematochiton elateroides Gorham, 1888. 



In the present study four species are recognized in the Neotropical 

 region and in the southwestern United States. H. elateroides 

 Gorham and H. carbonarius (Gorham) are kept in Haematochiton 

 while two forms heretofore described as Triplax are transferred to 

 Haematochiton. 



Distribution: The genus Haematochiton Gorham occurs only in the 

 Western Hemisphere. Specimens have been taken in the south- 

 western United States, Mexico, and Brazil. 



Methods and terminology. — Methods are the same as those used 

 for Triplax (see p. 3). 



"Neotropical" and other terminology are also the same as those 

 used in Triplax (see p. 3) . 



Acknowledgments. — For the genus Haematochiton, the author is 

 indebted to the same collectors and institutions for the loan of material 

 and Triplacinae specimens as for Triplax (see p. 3). 



The author owes special thanks to Dr. W. Wayne Boyle, Pennsyl- 

 vania State University, under whose guidance work on Haematochiton 

 was undertaken. 



Systematic treatment. — Haematochiton species display several 

 colors, including dull carbonaceous black, nitidous black with blood 

 red, and black with yellow. The general shape can best be described 

 as elongate-elliptical with anterior and posterior ends of the body 

 almost equally parabolically rounded, the anterior end somewhat 

 more obtusely rounded, however. The ratios of the length to the 

 width vary from 1.9 to 2.2:1. In lateral view the dorsal profile is 

 somewhat flattened medially. 



The head is visible from directly above. The eyes are finely 

 faceted, small, but vaguely coarser than in Triplax. The ocular 

 striae terminates at or behind the antennal insertions and the epistoma 

 is consequently immarginate. The antennae is about equal to three- 

 fifths to three-fourths of the pronotal basal width in length; its club is 

 4- to 5-segmented and is gradually emergent from the stem; segment 

 3 is subequal in length to segments 4 and 5 together. The maxillary 

 palpi are semicircular and are less than twice as wide as long and are 

 not armed with a distinct apical brush; the maxillary palpi are much 



