NEW BRITISH SPECIES, ETC., IX 1871. 55 



the authority of insects now believed to be Q. jnaicticolliSf 

 Thorns., from which these Yorkshire insects seem quite 

 distinct. 



For notes on this and the allied spp,, see Ent. Ann. 1869, 

 pp. 26-29. 



23. Philonthus xantholoma, Grav. 



^ var. variolosus, T>. Sharp, Ent. M. Mag., vii, 181. 

 Dr. Sharp names as above a highly developed male form 

 of the common sea-weed Philonthus, found rarely by him 

 on the coast in England and Scotland, and to which lie 

 refers the Berwick specimens referred to by Kraatz in 

 Ins. Deutschl., ii, 596, and the figure of P. xantholoma in 

 Du Val's *' Genera." This form is distinguished by its head 

 being usually much exaggerated in size (as is frequently the 

 case in cephalotes, fusais, sijlendens, jniella, and others of its 

 genus), with a proportionate increase in the degree of its 

 punctuation, and of the width of the front part of its thorax 

 for its reception (as is $ Lcemojihloeiis, &c.), causing the 

 posterior portion to appear more narrowed, and by the under 

 side of its abdomen (or " hind-body," as Dr. Sharp more 

 correctly terms it) being sparingly and coarsely punctured. 

 P. xcuitholoma, as Dr. Sharp points out, thus appears to 

 present the striking peculiarity of having two distinct forms 

 of its male sex ; one having solely the ordinary sexual mark 

 of abdominal emarginations, the other having in addition a 

 more widely and strongly punctured abdomen beneath. 

 Kraatz notes that the punctuation of the underside is much 

 less close in the male, as compared with the female of this 

 species. Sexual variations in punctuation on the upper 

 surface are exceedingly common, and are generally con- 

 sidered to be modifications of structure tending to facilitate 

 the successful union of the sexes, especially in aquatic species. 



