156 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.40. 



Coleopods with ventral plate very large, subquadrate, occupying 

 more than half of the anterior surface, but rather poorly chitinized; 

 margin nearly transverse, slightly angled in the middle, but not 

 produced. Anterior lobes broadly and deeply emarginate, the 

 mesial corners produced, much as in Eurelus, but broader and dis- 

 tinctly curved outward. Posterior lobes also somewhat broader 

 and stronger than in Eurelus. 



Gonopods very small and deeply retracted. 



Coalesced pleurae of the seventh segment of male forming a very 

 deep sinus behind and with the anterior face carried up into a narrow 

 transverse ridge much more prominent than in Eurelus. 



CENTRELUS FALCATUS, new species. 



Type. — Cat. No. 800, U. S. National Museum, Guanajuato, Mexico. 



Length of male about 38 mm., width about 3 mm.; female about 

 42 mm. by 4.5 mm. 



Color in alcohol dull olive or grayish green, the segments with a 

 pale posterior margin behind an equally short black band. Antennae 

 and legs of the same color as the segments, but the head and last 

 segment somewhat paler. 



Clypeal foveolse 4 on each side, at nearly equal distances; outer 

 pair located on the lower margin of the clypeus. Surface of clypeus 

 and vertex smooth, except for slight depressions and a few fine 

 irregular striations. 



Eyes somewhat oval or trapezoidal, of over 40 ocelli counted in 

 eight nearly vertical rows from the back toward the antennae, 4, 5, 

 6, 6, 6, 6, 5, 3, or in 7 obliquely transverse rows from above down- 

 ward 3, 5, 7, 8, 7, 6, 5. 



First segment with the anterior emargination not so broad and 

 deep as in Eurelus soleatus, the marginal ridge broader and the 

 lateral angle more rounded, not projecting below the second segment 

 as in Eurelus. 



Second segment with the anterior margin decurved, much as in 

 Eurelus. 



Surface of segments nearly smooth, shining with a dull luster, 

 very finely and indistinctly punctate and longitudinally striate above; 

 lateral and ventral striations very short, confined to the hindbelt; 

 surface convex below each striation. Segments behind the middle 

 of the body have the striations remote, only three or four on each 

 side, and produced into distinct sharp spines, curving obliquely 

 upward. Several of the posterior segments have the spines reduced. 



Last segment smooth, the apex very broadly triangular-rounded, 

 distinctly exceeded by the strongly convex smooth anal valves. 

 Preanal scale very broadly rounded. 



