WALSH DESCRIPTIONS OF N. AM. HYMENOPTERA. 77 



one of twelve species referred to Ischnus by Cresson, besides 

 Ischnus? paratus, Say, 1828, the % % only are known ; so that it 

 is left as yet uncertain to what genus they really appertain. Mr. 

 Cresson's specimen or specimens of this species, like mine, came 

 from Illinois, and one received by me from him since the above 

 was written agrees in every respect with the above description 

 down to the minutest details in the legs. 



\^Iscknus albitarsts, Cress., is doubtless the ^ of Cryptus amertcanus. 

 Cress., and varies much in coloration, especially efface and legs, and also 

 in size. — Cresson.] 



CryptllS nigricalceatas, n. sp. — c?. — Differs from the above only as fol- 

 lows : — I. The bilobed spot on the face is confluent with the white orbits, 

 and there are very narrow white orbits behind, but not above, the eye. 2. 

 The white line underlying the humeral suture is reduced to a mere basal 

 dot. 3. There is no "white spot above the anterior coxae," i.e. a more or 

 less abbreviated white line on the anterior edge of the collare. 4. In the 

 front, as well as in tlie middle legs, the 3d trochanter is black; in the 4 front 

 legs the terminal J of the tarsi is dusky : and in the hind legs the entire tar- 

 sus is so. Length d* .35 inch. Front wing c? .25 inch. 



One c? ; ? unknown to me. It is only by the two last charac- 

 ters recited above that this insect can be separated from albitar- 

 sts^ as the two first occur sometimes in that species. It may per- 

 haps be a mere variety of that species, but it will require a good 

 series of specimens to prove the fact. As a general rule, the col- 

 oration of the legs is pretty constant in this family ; but in Cr. 

 iridescens^ Cress., the hind tarsi vary almost as much in their 

 coloring as do those of albitarsts and nigricalceatus^ with all the 

 intermediate grades. 



[This is merely a variety oi albitarsts. — Cresson.] 



Cryptus [Iridescens, Cress.] — c?. — Black. Head opaque, very minutely 

 punctate, subpolished on the vertex and clypeus. Orbits very narrow and 

 subobsolete or sometimes obsolete on the face, interrupted opposite the 

 antennae, broader and almost always distinct to the commencement of the 

 vertex, and elsewhere obsolete, the terminal ^-f of the clypeus almost always, 

 the mandibles except their teeth, and the palpi, all white. Antennae brown- 

 black with the basal joint bright rufous beneath and the membranous base of 

 the ist joint of the flagellum often rufous all around, |-4 as long as the body, 

 rather slender, joint i of the flagellum 4-4^ times as long as wide ; joint 2 

 shorter by i ; the rest slowly shorter and shorter. Thorax opaque, closely 

 and very finely punctate, less so on the mesonotum which is subpolished ; 

 parapsidal grooves acute but not impressed ; the usual glabrous polished 

 spot on the hind edge of the mesothoracic pleura very obvious. Metano- 

 tum more coarsely rugoso-punctate, its carinate areas absent, except the 



