A. brevicollis Lee. Kept. Pac. R. R. Expl. & Surv. XII, 1857, p. 34. 

 Broadly obtusely oval and subdepressed ; black, elytra with or without a small 

 postmedian yellow spot near sides; occipital spots obsolete; antennae rufous: 

 . legs piceous, the tibiae and tarsi more or less obscure rufous. Surface lustre only 

 moderately shining, the reticulation somewhat rough, meshes unequal and of ir- 

 regular form, minute punctures very few, and when present within the meshes. 

 Outline nearly perfectly continuous ; prothorax rather broadly margined at sides ; 

 metasternum short between the mesocoxae and coxal plates, the distance between 

 them being less than one-third the length of the latter. Protarsi of male only 

 feebly incrassate, the anterior claw a little dilated toward the base, very nearly as 

 in seriatus and many lug ens. Length 9.8 to n mm. 



One of our largest species and apparently not overly common in 

 collections, though seemingly not rare within its limited range from 

 Northern to Central California. It is known to me from Humboldt, 

 Marin and Contra Costa Countries, and from Alma in the Santa Cruz 

 Mountains. The type is from the "upper Sacramento River." 



A. lugens Lee. Ann. Lye. Nat. Hist. New York, V, 1851, p. 203. 



sittiiralis Cr. Trans. Am. Ent. Soc. IV, 1873, p. 423. 

 var. per plexus Shp. On Dytiscidae, p. 498. 



In general appearance similar to and almost precisely intermediate between the 

 somewhat larger and broader brevicornis and the rather smaller and narrower 

 seriatus. The color is black, often slightly aeneous, the small sublateral yellow 

 spot of the elytra usually evident though often quite obscure, -the antennae darker 

 rufous or rufopiceous, the legs nearly black. The elytral reticulation is typically 

 fine, slightly scabrous toward the sides and apex, the small unequal areolae each 

 as a rule with a single minute puncture. Metasternum between mesocoxae and 

 coxal plates much longer than in the allied species. Male protarsi moderately 

 incrassate, the anterior claw varying from almost perfectly simple (as in the 

 type) to more or less distinctly arcuately thickened toward the base, in the same 

 fashion as in seriatus and brevicollis, there being some degree of modification 

 except in rare instances. Length 8.3 to 9.5 mm. 



Var. perplexus Shp. 



Specimens from Northern California, Washington, Vancouver and British Co- 

 lumbia are, as a rule, less finely reticulate than in typical lugens from the more 

 southern regions, and the form seems slightly more obtusely oval. They are the 

 perplexus of Sharp. These merge by insensible gradations into typical lugens, 

 such that a considerable proportion, more especially of California specimens, are 

 neither typically one nor the other, but occupy the debatable ground between. In 

 the series before me of what I judge to be typical perplexus, the length varies 

 from 9 to 9.5 mm. In all males seen the basal portion of the anterior protarsal 

 claw is a little thickened precisely as in the greater number of otherwise typical 

 lugens, as well as intergrading examples. 



Lugens including perple.nts is an extremely common species in 

 the far West, ranging from British Columbia to Lower California, and 

 extending East to Nevada, Utah (St. George), Arizona (Williams; 

 Chiricahua Mts. ; Final Mts.), New Mexico (Cloudcroft; Silver City; 



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