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. 24 b, 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; b, 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 discs. (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. Arcella. In all these specimens the inverted lip 

 is seen. Fig. a 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 Difflugice 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 Amceba villosa was seen to seize the 

 pscudopodia 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 oi Euglypha. 



Fig. 46 & 46 a. Side and front views of Euglypha Enchelys. 



Fig. 47. Bengal variety of same. ^^ 



Fig. 48. Euglypha 7nargaritacea (Stony Stratford). Fig. a, showing the 

 manner in which the test is made up of minute chitinoid discs, 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 fiw. 

 34 a. In D. margaritacea, the line 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 Tuthury. By Sir Oswald Mosley, Bart., 

 D.C.L., F.L.S. Together with the Fauna and Flora of the 

 District surrounding Tuthury and Burton-on-Trent. By Edwin 

 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 Burton-on-Trent, in 

 which the best of that bUssful beverage is brewed, should have a 

 double interest to us. We must therefore briefly record our thanks 



