4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 76 



Punctation. — The size, shape, depth, density, and uniformity of 

 distribution of punctures vary greatly between species, and furnish 

 many distinguishing characters in both sexes. In some species the 

 punctures are round ; in others they are elongated. The margin may 

 be sharply outlined or vague, and, in one group, each puncture has 

 an extended impressed area surrounding it, suggesting the term 

 " dhnpledy There are often two, and sometimes three, distinct sizes 

 of punctures in the same area. When the punctures of such an area 

 are of two sizes the condition is termed hipunctate, and the larger 

 punctures are called primary punctures and the smaller are called 

 secondary punctures. When the secondary punctures are very small 

 they are called minute punctures. This term is also applied to the 

 smaller punctures in cases where there are secondary punctures of 

 two sizes. The spaces between punctures are termed interspaces. 



The primary punctures vary in density, but can be classified in 

 three more or less distinct categories (pi. 2, fig. 9). When punc- 

 tures are so grouped that each has at least three others nearer to it 

 than the length of its own diameter, the condition is termed first- 

 degree density. When the punctures are arranged in rows, each 

 puncture separated from the proximate punctures in the same row by 

 interspaces equal to or shorter than the diameter of the puncture, the 

 condition is termed second-degree density. When the punctures are 

 widely scattered, being separated by interspaces greater than their 

 individual diameters, the condition is termed third-degree density. 



Head. — Tlie vei^tex extends from the occipital declivity to the 

 lowest ocellus. The presence and distribution of certain minute 

 punctures on the vertex, and their size, density, and regularity of 

 distribution are diagnostic in both sexes of several species (pi. 4, 

 fig. 28). The front extends from the lowest ocellus to the antennal 

 fossae. In this region the degree of shagreening is diagnostic. In 

 both sexes there are some differences between species in the presence 

 or absence of a caritia on the medial line just above the antennae; 

 another specific difference is the presence or absence of a shallow 

 groove extending along the top of this carina and continued above 

 on the impunotate stripe which extends downward from the low- 

 est ocellus. These characters are apparently not always constant 

 within tlie species. The density of the primary punctures varies 

 greatly between species and is a good diagnostic character, particu- 

 larly in females. Primary punctures are usually denser on the lower 

 front from eye to eye and, to a more limited extent, along the eye 

 orbits toward the vertex, than elsewhere on the front. They are 

 usually sparse in a region bordering the ocellar triangle below called 

 the preocellar region. In the males, the height to which the sec- 

 ondary punctures extend medially and along the eye orbits, and the 



