HOW WE FOUND THE MICROZOA. 295 



The bands in which the shells occur in the middle sands and 

 gravels bear evidence, too, of current bedding, aU of which facts taken 

 together with the presence of southern types of Mollusca, appear to 

 indicate an inter-glacial period, when the sea was free from iioating ice, 

 and the glaciers — if any — ceased to pour into it the mud which formed 

 the lower boulder clay. The partial denudation of the lower boulder 

 clay, however, supplied the materials for the middle sands and gi-avels, 

 together with the derived Arctic shells — sometimes found mingled with 

 the southern ones in a common tomb. The agency which disti-ibuted the 

 shells in the middle sands and gi-avels I beheve, with Mr. De Kance, 

 C.E., F.G.S., to have been marine currents. 



All this, and more, came of the preserving of a pinch of sand 

 out of the Saxicava-bored boulder found in the upper boulder clay of 

 Newton-by-Chester. 



Anyone wishing for the more detailed results will find them stated 

 in my papers, viz. : In the Quarterly Journal of the Geological Society 

 of Loudon for May, 1874, on " The Discovery of Foraminifera in the 

 Boulder Clays of Cheshire," and in the one for May, 1878, " On the 

 Glacial Deposits of West Cheshire, together with Lists of the Fauna 

 found in the Drift of Cheshire and adjoining counties." 



PARASITES OF MAN.* 



BY T. SPENCER COBBOLD, M.D., F.R.S. 



^Continued from page 213.] 

 Considering the importance of the new parasite (Filaria Bancrofti) 

 it was thought advisable to devote more space than usual to the 

 literature of the subject ; consequently, the remaining species of 

 filarifoiin nematodes may be dismissed with comparative brevity. It 

 happens, moreover, that much doubt hangs over the question of the 

 genuineness of several of the forms that require to be noticed. The 

 human strongyloids, on the other hand, are all of them well defined 

 species ; and, as will be seen in the sequel, they play almost as impor- 

 tant a role in the production of endemic disorders as do the Filaria) 

 themselves. In a general sense, the Guinea-worm may be spoken of as a 

 Filaria, but, for reasons given in my introductory treatise and elsewhere, 

 I prefer to consider this parasite as the type of an osculant genus 

 (Dracunculus.) The nomatoids variously placed by helminthologists under 

 the genera Sclerostonui, Anchylostoiiui, Dochmius, and so forth, are all of 

 them closely related to the Strongyli properly so called. As regards the 

 question of nomenclatui'e, I must leave it to Mr. Grove to say whether, 

 in the genera above mentioned, it is permissible for us to retain the final 

 component stoma unaltered. Many continental helminthologists no 



* Commnnicated by Mr. Hughes to the Microscopical Section of the Birmingham 

 Natural History and Microscopical Society, October 15th, 187H. On Dr. Cobbold's 

 behalf a microscopic slide was shown, containing namerous embryos of the Guinea 

 worm. The young worms had been mounted some twenty-five years previously. 

 They were originally taken from adult Dracuncnli in the possession of the late Sir 

 George Balltngall, of Edinbuigh. Altogether the specimens had been preserved 

 for upwards of half a century. 



