CERATOPHYLLUS, _Kolen_ C. fasciatus, _Bosc._ Rat C. londiniensis, _Rothsch._ House-mouse, Rat C. sciurorum, _Schrk._ Squirrel, Dormouse C. melis, _Wlk._ Badger C. mustelæ, _Wagner_ Bank-vole and Field-mice C. penicilliger, _Grube_ Bank-vole and Field-mice C. walkeri, _Rothsch._ Stoats, Voles, and Field-mice C. gallinæ, _Schrk._ Chickens and many birds C. fringillæ, _Wlk._ Sparrow C. garei, _Rothsch._ Many birds C. rusticus, _Wagner_ House-martin C. farreni, _Rothsch._ House-martin C. hirundinis, _Curt._ House-martin C. columbæ, _Gerv._ Pigeon C. styx, _Rothsch._ Sand-martin C. gallinulæ, _Dale_ Many birds: especially freshwater breeders C. vagabundus, _Bokeman_ Nests of Sea-fowl C. borealis, _Rothsch._ Gannet and Rock-pipit C. rothschildi, _Waterst._ House-martin CTENOPHTHALMUS, _Kolen_ C. agyrtes, _Heller_ Field-mice and Voles C. agyrtes nobilis, _Rothsch._ Water-rat C. bisoctodentatus, _Kolen_ Mole DORATOPSYLLA, _Jord. and Rothsch._ D. dasycnemus, _Rothsch._ Shrew RHADINOPSYLLA, _Jord. and Rothsch._ R. pentacanthus, _Rothsch._ Weasel R. isacanthus, _Rothsch._ Bank-vole PALÆOPSYLLA, _Wagner_ P. sorecis, _Dale_ Shrew P. minor, _Dale_ Mole P. kohauti, _Dampf_ Mole LEPTOPSYLLA, _Rothsch._ L. musculi, _Duges_ Mouse L. spectabilis, _Rothsch._ Bank-vole TYPHLOCERAS, _Wagner_ T. poppei, _Wagner_ Long-tailed Field-mouse HYSTRICHOPSYLLA, _Taschb._ H. talpæ, _Curt._ Mole ISCHNOPSYLLA, _Westw._ I. elongatus, _Curt._ Noctule Bat I. intermedius, _Rothsch._ Serotine Bat I. simplex, _Rothsch._ Natterer’s Bat I. octactenus, _Kolen_ Pipistrelle Bat I. hexactenus, _Kolen_ Long-eared Bat NYCTERIDOPSYLLA, _Oudemans_ N. longiceps, _Rothsch._ Pipistrelle Bat N. eusarca major, _Rothsch._ Noctule Bat APPENDIX C ON COLLECTING AND PRESERVING FLEAS There are two methods by which fleas may be preserved for study when they have been collected. The first is by keeping the specimens in small tubes of alcohol; the second is by mounting each in Canada balsam on a slide for the microscope. The advantage of the former method is that the material can be used for dissection. The student can do nothing without a microscope, though some of the commoner species can be identified with tolerable certainty by a practised eye which is assisted by a pocket-lens.