750 KiiPOKT — 1887. 



III. More recent authora, and tlie genera formed by them — Beddard : Typhceiix, 



Thamnodrilus, Microchceta. Benliam : Dlachata, Urobenus, Trigaster. 

 Fletcher: Didymogaster, Cryptodrihi", Notoscolex. Various other observa- 

 tions by these, and by Bourne, Eisen, [lorst, and llosa, &c. 



IV. Geographical distribution of these genera. 

 V, Description of primitive earthworm, with — • 



a. Complete circle of setae. 



b. Numerous nephridia. 



c. Short clitellum. 



(1. Single pair of testes, seminal reservoirs, ovaries, Sec. 



e. Nephridia modified as genital ducts. 



/. Gizzard and typhlosolo and intestinal glands. 



VI. Arguments in favour of the above statements, drawn from — 



a. Arrangement of setre in Perichseta, Diachaeta, Urochreta, penial sette 



of Acanthodrilus, scattered setre of many species. 



b. Numerous nephridia of Perichajtre, and nephridia of A. mnltiporwi. 



Alternation of nephridia in Plutellus. Lankester's theory sup- 

 ported. 



c. Short clitellum of raaay existing worms and in river worms. 



d. Genital system in Uroch.ieta, Biacha^ta, &c., with one pair testes. Sec. 



Increased production of spermatozoa necessitates increased means of 

 removal. Manner of modification of nephridia, as sperm-ducts and 

 spermathecse. 



VII. Comparative morphology considered very briefly. Form, clitellum, set3B| 

 position of malepore. Genital system in — 



1. Lumbricidfo, &c. 



2. Perichsetidte, &c. 



3. Titanus, &c. 



4. Eudrilus. 



5. Moniligaster. 



Alimentary system — degeneration of Pontodrilus and Criodrilus. 

 Vascular system — double dorsal vessel in Acanthodrilus sp., Microchseta, 

 and young Criodrilus. 



2. The Frohlem of the Mop-plant Louse (Phorodon hnmuli, Schp.ank) in 

 Europe and America. By C. V. Rilet, M.A., Ph.D. 



The author has been for several years carrying on investigations with a view of 

 ascertaining the full annual life-history of rJwrodon liumidi, and especially with a 

 view of settling the hitherto mooted question as to its winter life. The importance of 

 the inquiry, both from the economic and the scientific sides, is self-evident. The hop 

 crop, in all parts of Europe where it is grown, and especially in England, annually 

 suffers more or less from the ravages of this its worst insect enemy, and in some years 

 is a total failure. The same is true in North America, at least east of the Rocky 

 Moimtains, and last year the injuries of this Phorodon in the hop-growing regions 

 of the State of New York were .•^o great that many hop-yards were abandoned and 

 have since been ploughed up ; while but 10 per cent, of an average crop was har- 

 vested. From the purely scientific side, entomologists, notwithstanding the great 

 interest attaching to the subject, have been divided in opinion as to the identity, or 

 specific relationship, of the hop Phorodon and one that occurs on Prunus, while 

 the complete annual cycle of the insect's life has remained a mystery. After full 

 and satisfactory investigations the writer has satisfied himself that, contrar)' to the 

 prevailing impression among hop-growers and previous investigators, the Hop- 



