SOME REMAKKS ON THE BRITISH SPECIES OF LIMNIUS. 337 



Some Remarks on the British Species of Limnius {n-ith plate). 



By H. St. J. K. DONISTHORPE, F.Z.S., F.E,S. 



It will be remembered that, in the April number of the Ento- 

 violof/ist's Monthly Magazine of this year, Mr. Champion made some 

 remarks on the British species of Limnius. He said that Mr. Edwards 

 had sent him for examination four Liimiii from Norfolk, apparently 

 belonging to as many species, together with enlarged photographs of 

 the same, taken by himself. These photographs we now reproduce, 

 since it appears to us that the paper in question is very difficult to 

 follow without the illustrations to study with it. We now proceed to 

 quote some of ]\Ir. Champion's remarks. He says (speaking of figures 

 nos. 1-4 in the plate) : " If these specimens are to be referred to two 

 species only, as seems probable, there must be considerable variation 

 in the sculpture, etc., of the members of this genus, and it is, there- 

 fore, worth while calling attention to them. The chief difierential 

 characters noticed by Mr. Edwards between these four insects, which 

 for convenience are here referred to under the numbers 1-4, are as 

 follows : — 



1. Elytra coarsely punctuate-striate on the disc (the interstices appearing 

 convex), about two and a half times longer than the thorax; thorax shining on the 

 disc. 



2. Elytra sculptured as in no. 1, about two and a third times longer than the 

 thorax ; thorax dull and rugulose on the disc. 



3. Elytra finely and somewhat shallowly punctuate-striate on the disc, the 

 interstices flat, each with a distinct single series of punctures. 



4. Elytra as in no. 3, but without a distinct single series of punctures on each 

 interstice." 



He goes on to say that M. Grouvelle has examined Mr. Edwards' 

 insects and considers them to belong to two species only, nos. 1 and 2 

 being L. dari/dasi, Latr., and nos. 3 and 4 L. troghnhites, Gyll. Now 

 it seems to me that, if nos. 3 and 4 are the same species, there is 

 absolutely nothing left to differentiate between two species. We know 

 that size and colour go for very little in coleoptera, and what have we 

 left — form, structure, sculpture, and punctuation, and as these two 

 specimens differ from each other in all these the whole thing is 

 reduced to an absurdity. We note that Mr. Champion does not 

 express a decided opinion on the subject, and all the coleopterists to 

 whom we have shown the photographs have expressed great doubt as 

 to their being the same species. To make our illustration of the genus 

 more complete we add a figure (no. 5) of L. yinilaris, Rosenh. 



Whatever views one may hold as to what constitutes specific dis- 

 tinction in this genus, the British forms may for the present be dis- 

 tinguished as follows : — 



1. (0) Disc of thorax shining. 



2. (3) Elytra shallowly depressed on the disc. (larfjchini, Latr. (no. 1). 



3. (2) Elytra plain. 



4. (.5) Interstices of elytral strise with a distinct single 



row of punctures. trofilodyten, Gyll. (no. 3). 



5. (4) Interstices of elytral strise simple. ?-/rHZ((ri.s,Eosenh. (no..5). 



6. (1) Disc of thorax dull. 



9. (8) Thorax not narrowed until beyond the middle. no. 2. 

 8. (7) Thorax gradually narrowed from the base. no. 4. 



No. 2 may, of course, be the female of L. dari/dasi, but if that be so 

 then this sex must be extremely rare, since but tAvo other specimens 

 arc recorded. Colour is lent to the assumption that the female in 

 December 15th, 1901. 



