394 MANIPULATION. 



are to be met with in the Commercial Docks. The Stentor 

 csenileus has been found abundantly by the author in ditches 

 which communicate with a small stream in the Isle of Dogs, 

 close to the timber dock that opens into the West India 

 South Dock. The Daphni® are very abundant in the sum- 

 mer months in the dock waters, to the surface of which, in 

 the evening, they communicate a red colour, known to the 

 common people as spawn. The Branchipus stagnaUs, a highly 

 interesting crustacean, is found in small pools of soft water on 

 Blackheath : care must be taken in managing it, as it rarely 

 lives more than a day or two. In the mud of many ponds 

 may be obtained very interesting forms of Navicula and 

 Diatomea ; in the mud of the Thames, at various localities, 

 such as Lambeth, Woolwich, Tilbury, and Greenhithe, have 

 been discovered Xanthidia, and a very beautiful genus termed 

 Triceratium. In the mud of the Humber, near Hull, have 

 been found two beautiful species of Navicula, termed hippo- 

 campus and angulata, the former being an excellent test of 

 a quarter-of-an-inch object glass, the latter of an eighth or 

 twelfth ; both these will be shown highly magnified with the 

 other test objects at the end of this work. In the white pearly 

 matter often seen in peat bogs, and in the neighbourhood of 

 swampy pools, wUl be found an abimdance of loricse or shells 

 of Infusoria ; the most favourite localities being the bogs of 

 Ireland, Scotland, and Yorkshire. The sea shore and marine 

 plants yield a variety of beautiful forms; the guano, from 

 different parts of the world (as will be again noticed), the 

 stomachs of oysters, scallops, and other MoUusca, all abound 

 in some of the most elegant species of a genus named Cos- 

 cinodiscus, these being often associated with others in a 

 fossiHzed state. 



The Locality of the Wheel Animalcule. — Microscopists, from 

 the time of Baker, have nearly all stated that the wheel 

 animalcule is to be found in a reddish kind of slime deposited 

 from water that has been standing in leaden gutters, or even 

 in the dust that remains after all the water has been dried up, 

 which, when again moistened, will seldom fail to exhibit them. 

 Capt. Ford, after having sought in vain to procure them from 



