loos.] 239 



there both in the black and brown forms. The same may possibly 

 hold good for the Isle of Man, with the further limitation that only 

 the brown form of subrotundata occurs. I have not met with an 

 example of the type form atrata nor its var. brunnea in this particular 

 district, nor in some other parts of the Island in which I have col- 

 lected slightly at various times. 



Comparing the Manx specimens with a long series of the type 

 atrata and its var. brunnea, which I captured in company under loose 

 bark of a tree trunk by the Shropshire bank of the river Ceiriog, the 

 following points are worthy of notice. First, as regards size — 

 measuring in each case from apex of thorax to apex of elytra, 

 ignoring the head — the type atrata averages from II to 12 mm. in 

 length, a few smaller examples only 10 mm. The specimens of the 

 var. brunnea mostly measure 10 mm., a few mm., and a few larger 

 specimens 12 mm. The length of my Manx subrotundata is as a rule 

 13 mm., some larger ones 14 mm., while three or four examples only 

 measure 10 mm. As regards shape they are almost invariably much 

 broader in proportion than the type atrata, the elytra being more 

 dilated in the middle of the margins, the distance between the outer 

 raised line and the elytral margin being distinctly wider than in the 

 type. As Messrs. Johnson and Halbert remark " the reflexed margin 

 of the elytra is strongly developed, and extends almost to the apex." 

 The thorax is less closely punctured in the middle of the disc ; 

 though in a few specimens this difference is not so well marked as in 

 the rest ; the base of the thorax appears broader, and its posterior 

 angles project further beyond the line of the elytral margins than in 

 the type. 



My specimens confirm the same writers' statement that the sup- 

 posed difference in the length of the central raised line on the elytra is 

 not to be relied on as a distinction. Only in about 10 per cent, of the 

 specimens is the middle line the longest. As to the supposed occur- 

 rence of subrotundata in England, Messrs. Johnson and Halbert say 

 that there do not seem to be any satisfactory records. It may possibly 

 be that the few records really refer to occasional larger and broader 

 specimens of the type approaching the var. subrotundata, just as there 

 are occasional smaller and less broad specimens amongst the subro- 

 tundata- a partial reversion to the type form possibly. Certainly if 

 the true subrotundata occurred in England we should expect it to be 

 taken in some numbers, judging from its abundance in the localities 

 where it is found in Ireland and the Isle of Man. 



The dillicult questions as to the derivation of subrotundata in 

 Ireland and the Isle of Man, and the absence there of the type form, 

 remain for future investigation and speculation. 



Port Erin, Isle of Man : 



September 8th, 1902. 



