232 
ST. ALBANS AND ITS NEIGHBOURHOOD. 
miles of St. Albans, and such heaps would again reward careful 
and persistent search. 
VII. FAUNA. 
1. Protozoa. 
Scarcely anything has been done in Hertfordshire towards the 
investigation of microscopic forms of animal life. They are 
nevertheless of great interest, often of exceeding beauty, and the 
study of many groups presents but little difficulty to those who 
have a microscope, which is indeed an essential equipment for 
every naturalist. 
The freshwater Ehizopoda and their near allies the Heliozoa 
are very beautiful objects under the microscope, but they are 
mostly so minute that they cannot be seen with the naked eye, 
and scarcely even with a simple lens, requiring a compound 
microscope for their detection. They are, however, almost 
ubiquitous in clear but not rapidly-running water and wherever 
there is-moisture as in the moss on shady banks ; but the surest 
way of getting a fair number of species is to collect a handful of 
water-plants, especially peat-mosses (Sphagnum), from a shallow 
pool, and squeeze out the water, examining it drop by drop 
under the microscope. 
There is such a shallow pool on Bricket Wood Common, and 
in it the following species of Ehizopoda have been collected by 
the writer: —Amoeba proteus, striata, guttula, and Umax, Dactylo- 
sphserium radiosum, Pelomyxa palustris, Arcella vulgaris and 
discoides, Centropyxis aculeata, Difflugia oblonga, Penardi, 
lanceolata, lobostoma, pulex, tuberculata, oviformis, and constricta y 
Lesquereusia spiralis, Hyalosphenia inconspicua, Nebela tincta, 
Cochliopodium bilimbosum, Trinema enchelys, Sphenoderia lenta 
and dentata, and Pyxidicula operculata ; also the Heliozoa 
Actinophrys sol, Actinosphserium Fichornii, and Heterophrys 
Fochei. The full list is given as it is not a long one and very 
few species have previously been recorded for Hertfordshire. 
Until recently-the identification of freshwater rhizopods has 
been a matter of some difficulty, but now most of them can be 
identified from the monograph of the ‘ British Freshwater 
Ehizopoda and Heliozoa ’ by the late Mr. James Cash in course 
of publication by the Eay Society, and of which two volumes, 
containing the Amoebina or naked forms and the lobose 
Conchulina, have already been issued. For the rest of the 
Ehizopoda (the filose Conchulina) and the Heliozoa, it is 
necessary to consult the works of Hr. Penard until Mr. Cash’s 
monograph is completed. 
2. Mollusca. 
St. Albans is partly built on an outlier of the Heading Beds, 
which, with the London Clay, impinge upon the south-eastern 
border of the district, but otherwise the whole of the country 
