228 HYDROPHiLiDiE. [H''Jorhar(>s. 



being only found in the Tay district, where it has occurred rather commonly in a 

 pond on Moucreiffo Hill, Perth. 



According to M. Bedel this species at first sight seems very distinct, 

 hiut, as all the intervening links occur, he considers it to be only an 

 extreme variety of //. lividus, which he regards as an essentially variable 

 species. 



LACCOBIUS, Erichson. 



This genus comprises about fifteen species chiefly from Europe, but 

 one or two occur in I^orth America and Africa : they are small insects, 

 and are found in both fresh and brackish water either stagnant or 

 running ; they often occur in abundance in very small puddles ; if the 

 bottom is disturbed they rise to the surface ; the males have the second 

 and third joints of the anterior tarsi dilated. Until quite lately two 

 species only have been considered to be British, but Dr. Sharp, following 

 M. Bedel, has discovered that we possess four ; the distinctions are very 

 plain, but for their satisfactory recognition they require a high magni- 

 fying power. 



I. Interspaces of thorax quite smooth between punctures. 



1. Punctuation of elytra confused ......... L. SINFATUS, ilfo^s. 



2. Punctuation of elytra in reg-ular rows L. bipitnctattjs, J''. 



II. Interspaces of thorax alutaceous between punctures. 



1. Punctuation of elytra confused . . • L. alftacetts. Thorns. 



2. Punctuation of elytra in regular rows L. minutus, i. 



. Ii. sinuatus, Mots, {nigriceps, Thoms.). Oval, very convex ; head 

 black ; thorax black with sides broadly yellow ; elytra greyish-testaceous 

 with traces of darker markings, and wuth sides lighter ; legs and 

 Diaxillary palpi testaceous ; second joint of posterior tarsi almost twice 

 as long as third ; the" colotir is somewhat variable ; a variety occurs in 

 Avhich the clypeus is bordered with yellow on the sides (var. maculiceps, 

 Eott.). L. 3 1-4 mm. 



The largest and commonest species of the genus ; widely distributed throughout 

 the kingdom. 



Xi. alutaceus, Thorns. Slightly smaller than the preceding ; at once 

 distinguished by tlie sculpture of the thorax ; in other points it very 

 closely resembles L. sinuatus, with wdiich it has long been mixed 

 in our collections. L. 3| mm. 



Dr. Sharp considers this the rarest of our four species, but it is widely dis- 

 tributed ; London district generally ; Deal ; Southend ; Ramsgate ; Bognor ; Lyming- 

 ton ; Knowle, near Birmingham; Shrewsbury; Wicken Fen; Gnniley, Market Har- 

 borough ; Hunstanton ; Hartlepool ; Liverpool ; Scotland, Edinburgh and Aberlady. 



Zi. minutus, L. Considerably smaller than the two preceding ; 

 easily distinguished l;)y the alutaceous ground of thorax and the regular 

 rows of punctures on elytra ; apex of elytra without pallid spot. L. 2|-3 

 mm. 



Apparently not common; Cambridgeshire and Norfolk Fens; Needwood Forest, 



