W. J. SoUas — 0)1 Greensand Foraminifem and Sponges. 269 



Upper Greensand formation.^ Mr. Seeley ^ considered that they were 

 mostly derived from wasted Volcanic rocks, and the numerous 

 Volcanic erratics in the deposit seemed to lend some support to his 

 conjecture. It was with the full conviction that this explanation 

 was the true one, that I commei^ced an extended examination of 

 these grains : it was not long, however, before I convinced myself 

 to the contrary ; and I now feel assured that the majority of the 

 Glauconite granules are undoubtedly casts of Foraminifera. What 

 one is at once struck with is the constancy in form of a number of 

 these green grains, many of them constantly appearing as rounded 

 tetrahedra, divided into projecting lobes by deep sulcations, which 

 are generally lined at the bottom with white calcareous matter, 

 serving well to define the limits of each lobe. While examin- 

 ing these forms, which roughly resemble Bulimina, one comes 

 across others almost exactly similar to Textularia, Globigerina, 

 or even delicate Nodosarice. The grains resembling Bulimina in 

 shape are similar also in size, and the same is the case with the 

 Textularine, Nodosarine, and Globigerine forms. A section of one of 

 the Bulimine forms frequently reveals the septa of its chambers, or 

 something representing them, still extending to a greater or less 

 extent inwards between their casts. The cracks and interstices of 

 the coprolites of the Greensand are frequently injected with Glauco- 

 nite, and this proves at least the possibility of a similar infiltration 

 of the Foraminifera. Nothing, however, can be more conclusive 

 than the occasional occurrence of a green grain which is still 

 enveloped in the actual test of the Foraminifer whose chamber it has 

 filled ; here we have an undoubted case of a foraminiferal cast, and 

 as regards the other green grains, their resemblance in size and 

 shape to the Foraminifera accompanying them, and the ajopearance 

 of many of them in section, lead us to the conclusion that they like- 

 wise owe their origin to Foraminifera. 



The fossils we have thus far touched upon are probably contempo- 

 raneous with the Greensand itself We now approach forms which 

 are almost to a certainty derived from the Gault. The Coprolites of 

 our formation, since they first received their name from Prof. 

 Henslow, have passed through a somewhat eventful career. It was 

 soon seen that they were not what their name implies, but the con- 

 jectures hazarded concerning their real nature fell somewhat wide 

 of the mark, till Mr. Bonney published his valuable suggestions, by 

 which was indicated the first step towards the elucidation of their 

 origin. 



The first fact of importance to be noticed in reference to the 

 Coprolites is their marked connexion with previously existing, 

 highly decomposable, organic matter. The polished surfaces of the 

 teeth of Otodus, and of the palates of Pycnodiis, are seldom or never 

 encrusted with Coprolite; while their attached surfaces, to which 



1 Mr. Bonney, however, expressed his belief that many of the green grains would 

 be found to owe their origin to Foraminifera. — Proceedings Geol. Assoc, vol. iii.,no. 1, 

 p. 5. 



2 Geol. Mag. Vol. III., p. 305, 1866. 



