178 CEMONUS UNICOLOR. 



smooth and shining, the apical segment coarsely punctured and 

 deeply grooved down the centre. 



I have some hesitation in describing this insect as distinct from 

 C. morio ; but the differently formed tubercle on the face, the 

 closely punctured quadrate head, and difference in the neuration 

 of the wings, appear to characterize a different species : unless 

 some intermediate links unite them, I think it sufficiently distinct. 

 This insect was captured in Devonshire. 



Genus 10. CEMONUS. 



Pemphredon, pt., Latr. Gen. Crust, et Ins. iv. 84 (1806). 

 Cemonus, pt., Jurine, Hym. 214 (1807). 



Head large, subquadrate; eyes ovate and lateral; antennae 

 inserted at the base of the clypeus, not approximate ; the clypeus 

 produced in the centre of its anterior margin ; the labrum small 

 and triangular, the mandibles quadridentate, the inner tooth ob- 

 tuse, the rest subacute. Thorax ovate ; the metathorax rounded 

 or obtusely truncate; the superior wings with one marginal and two 

 submarginal cells, the first submarginal receiving both the recur- 

 rent nervures, the first a little before the centre, the second near 

 its extremity ; the second submarginal cell subquadrate, widest 

 towards the marginal. Abdomen ovate and petiolated, the pe- 

 tiole curved, and about as long as the first segment. 



1. Cemonus unicolor. 



C. ater; metathoracis basi spatio cordiformi, limbo laevi medi- 

 ocri utrinque crenatura circumscripto. 



Pemphredon unicolor, Latr. Gen. Crust, et Ins. iv. 84. 



Van d. Lind. Obs. ii. 83. 6. 



Zett. Ins. Lapp. 441. 2. 



Curtis, Brit. Ent. xiv. t. 632. 



Cemonus unicolor, Jurine, Hym. 214 (2nd Fam., note, without the 

 synonyms). 



Shuck. Foss. Hym. 200. 1. 



Dahlb. Hym. Europ. i. 255. 155. 



St. Farg. Hym. iii. 942. 



Wesm. Hym. Foss. Belg. 119. 1. 



Female. Length 4-4-J lines. Shining black ; the vertex distantly 

 punctured, more closely so in front of the ocelli, the punctures 

 running into striae on the face ; a deep longitudinal impression 

 runs from the anterior stemma to the insertion of the antennae ; 



