24 CALIFOEXIA ACADEMY OF SCIENCES. 



very distinctly, "uider than long in tlie former. It is true 

 that the sexes in these cases are ditterent, but on examining 

 a full series of a closely-allied species — retrusa — described 

 below, it is readily seen that the sexual differences in the 

 general form of the body, even of the head, are almost ab- 

 sohitely inapjireciable; it is in fact a forcible instance of 

 what Dr. LeConte (Trans. Am. Ent. Soc. YI, p. 213) calls 

 the polarity and, it might bo added, concentration of sexual 

 characters. Here we have the sexual modilicatious at the 

 abdominal vertex extremely well marked, elsewhere, how- 

 ever, if Ave except a slightly longer second antennal joint in 

 the males, they are not at all apparent. 



10 — L, luctuosa 11- sp. — Form slender; liead, pronotiim and abdomen 

 ^^brougliout black; elytra rufo-piceous, not paler at tip; legs dark brownish- 

 llavate; antennre piceons, pale at tbe tip; pubescence almost absent anteriorly, 

 moderately sparse and fine on the elytra, somewhat dense on the abdomen; 

 integuments polished. Head moderate, distinctly longer than wide; base 

 truncate in the middle, angles rather narrowly rounded, sides parallel and 

 very ft ebly arcuate; vertex moderatelj'' produced, truncate at apex, feebh' 

 arcuate in the middle; punctures feeble, small and rather sparse; median line 

 rather l)r()ad, c(jual throughout; autenufe distinctly shorter than the head 

 and prothorax together; ba^al joint distinctly longer than the next two com- 

 bined, second slightly shorter than the third, sub-8qi;al to the fourth. Pro- 

 thorax fully as long as wide, equal in width to the head; sides excessively 

 feebly convergent posteriorly throughout and very feebly arcuate; base 

 broadly sub-truncate in the middle; apex broadly, rather feelily and equally- 

 strongly arcuate; nuchal sinuatiou feeble, two-fifths as wide as the disk; 

 anterior angles rather narrowly rounded, basal broadly so; disk transversely, 

 evenly and moderately convex, very feebly, finely and rather sparsely' jjuuc- 

 tate in the middle, more closely so at the sides; median impuuctate area 

 moderate in width, even throughout, not impressed. Elijtra at base slightly 

 wider than tin; pronotuni: sides parallel and feebly arcuate; together 

 broadly, roundly and rather feebly sinuate behind; disk less than one-third 

 longer than the pronotuni, one-fourth longer than wide, feebly and narrowly 

 imprC'-sed along the slightly elevated suture, finelj', feebly, evenly, sub- 

 asperately and rather sizars ly punt:tate. Ahdomcn slender, scarcely nar- 

 rower than the elytra; sides straight and parallel; surface minutely, very 

 densely, sub-asperately and evenly punctate. Leijn rather slender; first joint 

 of the postericn- tarsi one-thir 1 longer than the second, much shorter than 

 the liftb; anterior tarsi slightly dilated. Length 4.2 mm. 



8an Francisco, 1 ? . 



