Bibliographical Notices. 245 
Fig. 23, Six-spined variety of D. aculeata. 
Fig. 24. Front view of D. spiralis. Test composed of chitinoid cylinders. 
24 a, side view of the same. 244, a portion of a test, showing 
the intermixture, in some cases, of minute diatoms. 
Fig. 25. D. spiralis. In this specimen, the test is entirely made up of 
ordinary mineral particles. 
Fig. 26. D. symmetrica, showing the rectangular hyaline plates: a, form 
of aperture; 6, a more compressed specimen, in which the 
aperture (e) is nearly closed; d, a few detached plates. 
Figs. 27 to 33 represent the series of forms exhibiting the transition 
from the ordinary mineral and chitinoid elements of the test to 
the evolution of the colloid dises. (See pages 231-234.) 
Figs. 34 & 35. Varieties of D. Arcella. 
Fig. 36. Puckered test of D. Arcella, which has hitherto been regarded as 
a distinct species, under the name of D. angulata. 
Fig. 37. Front view of D. Arcelia. In all these specimens the verted lip 
is seen. Fig. @ shows the invariably hexagonal pitting or reticu- 
lation of D. Arcella. (This can only be made out, however, in a 
mounted and crushed test, under a high power.) 
Fig. 38. Young test of D. Arcella. 
Fig. 39. This figure represents two Difflugie apparently united by their 
orifices in the manner which has been regarded by some writers 
as indicating ‘‘ conjugation.” The remarkable feature in the 
present example is, that the supposed conjugative act is being 
performed by individuals which, by the same writers, have been 
regarded as constituting distinct species. 
Fig. 40. In this case, a specimen of Amba villosa was seen to seize the 
pseudopodia of the Difflugia, and force the greater portion of its 
own body into the Difflugian test. After a time it again emerged, 
the villous organ, which had become concealed within the test, 
being the last portion to leave it. 
Figs. 41 to 45. Varieties of Huglypha. 
Fig. 46 & 46a. Side and front views of Huglypha Enchelys. 
Fig. 47. Bengal variety of same. 
ig. 48. Huglypha margaritacea (Stony Stratford). Fig. a, showing the 
manner in which the test is made up of minute chitinoid dises, so 
arranged that each one is united to those surrounding it by six 
equidistant connecting bands. In Difflugia Arcella the test almost 
‘invariably fractures through the hexagonal spaces, as seen in fig. 
34a. In D. margaritacea, the lime of fracture as invariably tra- 
verses the spaces between the discs, proving that they are the 
thickest and strongest portions of the structure. 
BIBLIOGRAPHICAL NOTICES. 
The Natural History of Tutbury. By Sir Oswatp Mos ey, Bart., 
D.C.L., F.L.S. Together with the Fauna and Flora of the 
District surrounding Tutbury and Burton-on-Trent. By Epwin 
Brown. London: John Van Voorst, 1863. 
As Englishmen, we of course have a vested interest in all that con- 
cerns ‘‘bitter beer,’ and accordingly, as English naturalists, the 
physical peculiarities of the district around Burtoa-on-Trent, in 
which the best of that blissful beverage is brewed, should have a 
double interest to us. We must therefore briefly record our thanks 
