294 MONOGRAPHIA IIYDR^NARUM ANGLLT.. 



not so thickly punctured. This species is often confounded 

 with //. testacea, but it is much larger, its form is more linear, 

 the head is of a different form, the sides being nearly parallel, 

 and the eyes scarcely prominent : the thorax is much larger and 

 broader in proportion, not so coarsely punctured : the striae of 

 the elytra are wider apart, and likewise not so coarsely punctured. 

 In some specimens the head is of a pale pitchy-testaceous, but it 

 is generally concolorous with the body, in which respect it also 

 differs from //. testacea, which always has a black head. 



Taken at Hebden-bridge, by Mr. Gibson and A. H. Davis, 

 Esq. 



Sp. 4. Hyd. nigropicea. Piceo-jiigra; cajjite de?ise punctaio, 

 oculis prominentibas: thorace hreviore, dense punciato,fovei& 

 quatuor leviter impressis : elytris oblong o-ovatis, stib-trnn- 

 catis, punctato-striatis, striis sub-confluentihus : antennis, 

 pedibus, palplscpie rnfo-testaceis. (Long corp. 1 lin.) 



About the size of H. riparia : the eyes are more prominent, the 

 thorax is shorter, the elytra are ovate and subtruncate, whereas in 

 riparia they are linear, and rounded at the apex. 



I have once met with this species near London. Epping ; 

 E. Doubleday, Esq. I have also seen several specimens from 

 Hebden-bridge. 



Sp. 5. Hyd. melanocephala. Testacea ; capite nigro-jnceo, 

 proj'unde punctato, ocidis magnis, protnineniibus : thorace 

 brevi, laterihus dilaiatis, dense punctatis, foveis quatuor 

 leviter inijiressis : elytris latiorihus, ovatis, vix truncatis, 

 leviter jiunctato-striatis : antennis, 2)edibusque 2iallide tes- 

 taceis, ijaljiis testaceis, apicibus nigris. (Long. corp. 1 lin.) 



Allied to the foregoing, but known by its pale colour, it is 

 altogether broader and shorter in proportion : very distinct 

 from H. testacea, which it resembles in colour ; it is much 

 larger and broader, the thorax is considerably dilated at the 

 sides, and very short ; it is also more delicately sculptured 

 throughout. Netley, Salop ; Rev. F. W. Hope. 



Sp. 6. Hyd. testacea. Pallide piceo-testacea : cajnte 

 nigro, dens^ punctato, oculis prominentibus : thorace 

 dngustiorc, later^b^s vix dilatatis, profunde punctato, ad 



