New Genus of British parasitic Hymenopter a. 257 



Genus Pemphre v don Latr. 



Subgenus 1. Diodontus Curt., type Pemphredon tristis V. D. L. 



2. Passalae\ms Shk., type Pemphredon insignis V. D. L. Dio- 



dontus Curt. 



3. Ceratophorus Shk., type Pemphredon morio V. D. L. 



4. Pemphredon Lat., type Crabro lugubris F. 



5. Cemonus Jur., (? Dineurus Westw.) type Cemdnus unicolor 



Jur. 



Art. VIII. Description of a new Genus of British parasitic Hymen- 

 opterous Insects. By J. O. Westwood, Esq., F.L.S., &c. 



Of all the animal organs, none have so greatly perplexed 

 physiologists as the antennae of insects. If regarded as tactors, 

 or feelers, the fact that, in many species, these organs are so 

 minute as to be incapable of reaching beyond the mouth, 

 opposes such opinion : if as organs of the sense of smelling, or 

 of hearing, we find them, in many instances, encased in a hard 

 and horny covering, which seems quite incapable of permitting 

 the passage either of scent or sound ; whilst, at the same time, 

 the singular and almost endless varieties of form which these 

 organs exhibit in the different species, and more especially 

 the different manner in which they are often constructed in 

 the opposite sexes of the same species (the males having them 

 ornamented with branches, whorls of hair, &c), seem to indi- 

 cate the existence of some other use for these appendages, 

 distinct from touch, smell, or hearing. This is not, however, 

 the place to enter into this highly interesting question, my 

 present object being to describe a new British hymenopterous 

 insect, remarkable for the beautiful structure of its antennae, 

 at least in the males. 



Antennae having some of the joints furnished with long 

 and slender cylindrical processes are termed ramose, or 

 branched. This structure is confined almost exclusively to 

 the males. It exists in some coleopterous species, but is by 

 no means of common occurrence in that order. The tribes 

 of predaceous beetles (Cicindelidae, Carabidae, and Dyticidae), 

 the lamellicorn beetles (Scarabae^us Linn.), the clavicorn 

 beetles (Silpha, Dermestes, &c), the black portion of the He- 

 teromera, the weevils (Curculio Linn.), and the Brachelytra, 

 or rove-beetles (Staphylinus Linn.), do not present any species 

 having ramose antennae : indeed, it is chiefly in insects of 

 exposed habits, such as the Elateridae, Cerambycidae, &c, 

 that we find this structure most prevalent. No hemip- 

 terous nor homopterous insect is furnished with branched 

 antennae; neither can any of the Orthoptera be said to be thus 



Vol. I. — No. 5. n. s. u 



