British Species o/Ualiplus. 107 



in both //. riiJicoUis and heydeni the thoracic stilaa are about 

 one-third the length of the tiiorax ; of //. loehnckei he says 

 that there is a semicircular ]iit inside each stiia, while he 

 mentions that in H, schaumii, Schilskj, the strioe are short 

 and deep. Reitter(i5) uses the presence or absence of a 

 transverse depression of the thorax between the striae as a 

 systematic ciiaracter, H. ruJicuUis having no such depression, 

 while its varieties — ■multiijunctatus and hejideni — have it, tlie 

 former variety being distinguished from the latter by having 

 the strias straight instead of curved. He speaks of H. loelmchei 

 as having an interstrial depression. Ganglbauer (7) also 

 lays some stress upon these characters, describing them in 

 each species and variety. 



I have found the strise of some use as an aid in determining 

 some of the species, but the presence or absence of a depres- 

 sion between them seems quite useless. In II. immaculataa 

 the strise are short and incurved, while in II. loehnckei, noma.r, 

 and apicaUs they are long and practically straight. In 

 II. ruJicoUis and heydeni, however, although usually short 

 and almost straight, they are sometimes distinctly incurved. 



On this character, therefore, it is often easy to confuse 

 //. riificoliis and immaculatus, on the one hand, and //. rufi- 

 colUs and loelinchei on the other. In II. flaviaiiUs the striai 

 are usually very short, sometimes scarcely more than a rather 

 large puncture, but occasionally longer ones occur. 



The Characters of the Male. 

 1. The Anterior Tarsi and Tarsal Claws. 



Apparently Edwards was the first author to recognize any 

 differences in the claws of the anterior tarsi of certain species 

 of the group ; but heonly menfioued them in the case of two 

 species, II. rujicollis and heydeni. Accoiding to the cha-» 

 racter of the claws our species can be separated into two 

 groups — //. heydeni, apicalis, and nomax, having tiie pair 

 equal or subeqiuil, and II. riificoliis, toehnckei, and inmacu- 

 latus, having them distinctly unequal. //. fiuviatilis should 

 probably belong to the first group, but the difference between 

 the two is more noticeable than in nomaoa, for instance, 

 though much less than in riificoliis. 



The form of the claw-bearing segment is useful for distin^ 

 guishing H. immacidalus, in which it is normally short and 

 ratiier thick, from ivehnckei and riificoliis, in which it is 

 normally long and therefore thinner in appeaiance. 



If the claws are removed and examined under high magni^ 



