Mr. J. S. Baly on new Genera and Species of Phytophaga. 433 



between the dark and light portions. Such a line of demarca- 

 tion makes its appearance when the body has grown to about 

 0*3 millim. in length ; the paler and darker portions then appear 

 very like a small acorn in its cup. Subsequently the pale por- 

 tion becomes elongated, and grows into the caudal part of our 

 structure ; whilst the darker head portion gradually acquires a 

 conical form, and the foremost membranous part commences its 

 motory activity ; but the tail, contrary to what occurs at a later 

 period, is still distinguished from the head by its much lighter 

 appearance, and, instead of seminal filaments,' its surface is co- 

 vered with small, roundish, transparent granules (vesicles?), 

 thus reminding one of the globular or elongated bodies on which 

 the seminal filaments are developed, for example, in the body- 

 cavity of the Annelida. 



XLIX. — Descriptions of new Genera and Species 0/ Phytophaga. 

 By J. S. Balv. 



Fam. Sagi-id^e. 



Sagra mutabilis. 



S. supra subopaca, subtus nitida ; antonnis extrorsum nigro-purpu- 

 rcis ; tliorace subquadrato, anticc vix producto, angulis anticis 

 modice promiiuilis ; clytris basi thorace multo latioribus, humcris 

 subprominulis, a basi ad apicem angiistntis, supra couvcxis, intra 

 humeros sat |)rofunde imprcssis, subtilitcr coriaccis, infra basin 

 minus profunde traiisvcrsiin im))rcssis, tcnuissime gcmcUato-punc- 

 tato-striatis, striis fere omnino deletis. 



A. Corpus rufo-igueum. C. Corpus viridi-caeruleum. 



B. Corpus viridi-aureum. D. Corpus purpureura. 



Mas. Fcmoribus posticis sat elougato-iucrassatis, elytra sat 

 supcrantibus, subtus bidentatis, deute antico majorc ; tibiis ojus- 

 dem paris apice mucronatis bidentatisquc, dentc cxteriore valido, 

 abdominis segmento prinio deplanato, crebre punctato, tomcntoso. 



Ftrnt. Elytris oblongis, posticc minus angustatis ; fcmoribus 

 posticis elytra vix supcrantibus, subtus ante apicem crista brevi 

 instructis ; tibiis ejusdem paris apice breviter mucronatis. 

 Long. 8-1 1 lin. 



Hab. Cambodia, Siani. 



This lovely species is most closely allied to S, speciosa, Lac. : 

 it agrees so completely in nearly all its characters with that in- 

 sect that a detailed description would be almost useless. I shall 

 therefore confine myself to the points of difference between the 

 two insects. 



In S. mutabilis ^ the antennae are equally long, but stouter ; 

 the thorax is usually (but not always) slightly broader; the 

 elytra are much broader at their base, the humeral callus being 



Ann. &; Mag. N. Hist. Ser. 3. Vol. xiv. 28 



