Genus Hystrichopsylla, Tschb.1880. Taschenberg, Die Flohe, p. 83.This genus has but a single species:—Hystrichopsylla obtusiceps, Ritsema1826. Curtis Brit. Ent., III., No. 114 (Pulex taipæ).1831. Macquart, Ann. d. Sci. Nat., XXII., p. 405 (Pulex terrestris).1868. Ritsema, Tijds. voor Entom., 2 ser. III., p. 173 (Pulex obtusiceps).1880. Taschenberg, Die Flohe, p. 83 (Hytrichopsylla obtusiceps).This remarkable flea has a heavier covering of spines and bristles than occurs in any other species. The head combs are on the discs of the cheeks with the spines pointing backward (as in Typhlopsylla gracilis and fraterna), instead of on the lower edges, there being 10 spines on either side. The first joint of the maxillary palpi is the longest. Pronotal comb with 20 spines on either side. The comb on the first abdominal segment consists of 20 spines on either side; that on the second segment, of 12 on either side, and that on the third segment, of 7 on either side. The tarsi are slender. Colour, chestnut-brown. Length of male, 3.5mm., of female, 5–5.5mm. It has been reported as occuring on Talpa europœa and Arvicola arvalis, in various parts of Europe.