Transmission 23 



his statistics to assist the present inquiry. In Qaliubia, of 700 

 persons examined 44 per cent showed vesical Bilharziosis. In 

 Sharqia, (Sij per cent of the 1,089 patients attending the travelhng 

 hospital for ankylostomiasis at Minia el Qamh, and 70-9 per cent of 

 832 attending at Bilbeis showed Bilharzia eggs in the urine. 



The Mollusc a of Egypt. 



The fresh-water molluscs of Egypt have been studied by a 

 number of malacologists, and have been well described and illus- 

 trated, especially by Jickeli (1874) in "Fauna der Land und 

 Siisswasser Mollusken Nord Ost Afrika's," by Bourgnignat in 

 various papers from 1863 to 1883, by Innes (1884) and Pallary 

 (1909). The last writer, in his "Catalogue de la Faune Malaco- 

 logique d'Egypte," summarizes very completely the work of pre- 

 vious collectors. Pallary's list (excluding land forms) is given in 

 the adjoining table and in parallel columns are indicated : (a) 

 Those species previously described in the works of Jickeli in 

 1879 ; (&) the species mentioned as having been examined as 

 possible transmitters of Bilharzia in the writings of Lortet and 

 Vialleton, Sonsino, and Looss, are marked respectively by the 

 lettering " V." " S." " L." ; and (c) the forms collected and 

 examined in the course of the present inquiry. It will be seen 

 that of the fifty forms catalogued by Pallary, Lortet and Vialleton 

 mention only four, Sonsino specifies nine, and Looss eight. It 

 will be noted that all the forms mentioned by Looss had been 

 examined also by Lortet and by Sonsino. In the subjoining table 

 is tabulated a complete list of the trematode larvae hitherto found 

 in Egyptian molluscs. A comparison of the finds of Sonsino and 

 Looss shows that each investigator met with developmental forms 

 overlooked by the others, and that the investigations of the present 

 inquiry revealed a still larger number of new forms. 



In the Natural History section of the magnificent "Description 

 de I'Egypte" prepared by the authority of Napoleon during the 

 French occupation in 1799-1801, eight of the commonest fresh- 

 water molluscs are recorded and beautifully illustrated. In three 

 of these we have found undoubted Bilharzia larvae within half an 

 hour's journey by tram and train from Cairo. 



These are extraordinary facts in the light of Professor Looss's 

 repeated contention during the past twenty years that he had 

 examined hundreds of specimens of all the molluscs occurring in 

 the Nile Valley without finding any developmental form which 

 might have been brought into relation with the Bilharzia worm. 



