162 THE ENTOMOLOGIST. 



H. palustris, Er. — Head black; thorax, except extreme 

 margins, and elytra dark. Distinguished from the preceding by 

 its colour, smaller size, less elongate thorax, and by the fact that 

 each elytron has nine or ten rows of distinct, but less deep, 

 punctures, which give the insect a smoother appearance. 

 Length, § line. Very local and rare. Askham Bog, York, and 

 Cowley ; it may always be found sparingly in the former locality. 



C. Thorax entirely dark. 



The three species that form this group, although very distinct 

 from all the other species of the genus, are with difficulty 

 separated one from another by descriptions, although their 

 differences may easily be seen on a comparison of types. 



H. riparia, Kug. — Distinguished by its size, and by having 

 nine or ten rows of almost square punctures on each elytron; 

 elytra broader than thorax, with sides rounded, but still some- 

 what parallel-sided. Length, 1 line. The commonest and most 

 generally distributed species of the genus. 



H. angustata, Sturm. — Distinguished by its parallel elytra, 

 which are hardly at all rounded, and by having two strong longi- 

 tudinal impressions on the disc of the thorax, and, above all, by 

 the fact that each elytron has eight rows only of strong, almost 

 square, punctures, which give the insect a more coarsely 

 punctured general appearance. Length, f line. Local and rare. 

 The Wansbeck (Wallington, Northumberland), Falkirk, Polinont 

 (Glasgow), &c. A north country insect. 



//. nigrita, Germ. — Often confounded with H. riparia, which 

 it very closely resembles, but may be separated by its smaller 

 size, oval elytra (which are much more rounded than in either of 

 the preceding species, and are dilated behind), and by the fact 

 that each elytron has nine rows of almost round punctures. 

 Length, § line. Local. North of England, Scotland (Glasgow), 

 Holm Bush, Birdbrook (Essex), &c. 



II. Each elytron with at most six rows of punctures between 

 the suture and the apical angle. 



A. Punctuation of elytra very strong and regular, and plain 

 at the apex. 



a. Length, 1 line. Elytra with parallel sides, rounded at the 

 apex only ; thorax unicolorous. 



H. gracilis, Germ. — A very distinct species, which may be at 

 once known by its large size, shining pitchy appearance, and very 



