Sept., I9I7-] Fall: New Dytiscid^. 171 



as a ground sculpture, that prevails in triangularis. Length 4.2 mm. ; width 

 1.9 mm. 



The unique type was taken at Winnfield, Louisiana, by Mr. G. R. 

 Pilate, from whom I received it. 



Mr. Sherman (in lift.), alluding to the Sauk City, Wisconsin, 

 species mentions having seen a specimen sent by M. Oberthur, of 

 Rennes, France, labelled Opclousa La. It is more than likely that this 

 specimen belongs to the present species rather than to triangularis. 



The general facies of pilatci and triangularis is somewhat similar 

 to concinnus and allies, and the modification of the male antennae in 

 divcrsicornis of the concinnus group suggests a relationship, so that, 

 tentatively, the two species here described may be placed before 

 diversicornis, though it must be confessed there is little else indi- 

 cating such association. 



Hydroporus cocheconis new species. 



Of the concinnus type ; elongate, obtuse in front, rather pointed behind, 

 flavo- to rufotestaceous, elytra with two broad, indented and more or less con- 

 fluent transverse black fasciae ; integuments moderately shining, minutely 

 reticulate, finely and evenly punctate throughout, the punctures separated on 

 the average by twice their own diameters ; pubescence very fine and sparse. 

 Antennas yellow, terminal joint largely blackish, the apices of one or two of 

 the preceding joints occasionally dusky. Head feebly impressed each side, 

 clypeus not thickened. Sides of thorax very feebly, evenly arcuate, margin 

 moderately wide in front, much narrower posteriorly, disk with the apical 

 margin infuscate throughout the width of the head, base similarly but usually 

 more narrowly infuscate, sometimes not at all so. Elytra one half longer 

 than wide, base with or without one or two black discal spots, the two broad 

 black indented fasciae (typical of the group) connected narrowly along the 

 suture, and often at the middle of each elytron, more rarely again toward the 

 sides ; fasciee not attaining side margins, the suture dark throughout. Body 

 beneath and legs entirely rufotestaceous ; metasternum and coxal plates 

 coarsely rather closely punctate, first two ventrals less coarsely and closely so, 

 third ventral moderately punctate, last three segments finely and sparsely so. 

 Length 3 to 3.7 mm.; width 1.4 to 1.8 mm. 



Described from a series taken by the writer at Farmington, New 

 Hampshire, in July and August, in the gravelly shallows of the 

 Cocheco River. 



There is no appreciable sexual difference in surface luster, and 

 very little in the dilatation of the front tarsi, which are only moder- 

 ately wide in the male. As in all species of the grouji, the anterior 



