156 



MK. J. S. BALT Olf SOME GENEBA 



Fig. 9. Posterior antenna of ditto, x 400. 



10. Anterior foot-jaw of ditto. X 400. 



11. Posterior foot-jaw of ditto. X 400. 



Plate XIII. 



Fig. 1. Cyonhasoma rigidum, n. sp., female, x 250. 



2. Anterior antenna of ditto. X 400. 



3. First swimming-foot of ditto. X 400. 



4. Abdomen of ditto, with attached ova and caudal appendages. 



6. First pair of swimming-feet of Acontiopkoms angulatus. x 400. 

 6. Fifth foot of ditto. X 400. 



Descriptions of some Grenera and Species of GalerucirKB. 

 By Joseph S. Balt, E.L.S. 



[Eead 2nd February, 1888.] 



The examination of some extensive genera of Galerucince — Haplo- 

 sonyx, Cerotoma, and others — in which the anterior acetabula 

 are described as closed or entire, has convinced me that the views 

 expressed by myself in the Ent. Month. Mag. vol. xxiii. p. 268 

 are correct. In any long series of individuals belonging to these 

 various genera I have almost invariably found some species in 

 which, whilst certain specimens have the acetabula closed, others 

 have them open, in some instances these opposite states occurring 

 on the different sides of the same individual. This is strikingly 

 the case in Cerotoma and Monolepta. Under such circumstances 

 it must, I think, be conceded that the state of the acetabula 

 cannot be regarded as a primary, even if it can be retained as a 

 secondary character. It becomes therefore necessary to dis- 

 cover some other and more stable means by which to divide the 

 Galerucince into primary sections. This, 1 venture to suggest, 

 will be found in the form and structure of the hinder portion of 

 the prosternum. In a large number of genera, for instance 

 Saplosonyx, (Enidea^ and numerous others, the prosternum, as in 

 the Chrysomelidse and the earlier groups of the Phytophaga, is 

 produced just before its base into a distinct lobe or process, the 

 sides of the lobe (in cases where the acetabula are closed) being 

 connected with the apices of the epimera, whilst the hinder 

 margin of the lobe is free, and usually applied to the anterior 

 surface of the mesosternum. In a second large section of the 

 family, represented by Galeruca, Aulacophora, &c., this subbasal 

 lobe is entirely absent, the prosternum being couuected without 



