W. J. Sottas — On Greensand Foraminifera and Sponges. 271 



fossilization of organic matter, or of the immediate products of its 

 decomposition. This does no violence to the obvious meaning of the 

 word, which may as correctly be derived from " manure-stone " as 

 from "fossil-dung." 



A Coprolite thus serves as an index of pre-existing organic matter, 

 and the task of the Palfeontologist lies in definitely determining from 

 what particular form this organic matter has in each particular in- 

 stance been derived. With the fossil remains of Eeptiles, Crustacea, 

 Molluscs, or of Ventriculites, the question could never have presented 

 more than a passing difficulty, but in certain other cases it has proved 

 so far problematical that no satisfactory solution has been received 

 up till very recently. I now propose to suggest an explanation 

 which has lately been worked out, and which to my mind seems 

 thoroughly to meet the case.' 



The ordinary nodules impress one with their resemblance to 

 sponge forms at first sight, some are rod-like, solid throughout, and 

 attached at one end {Rhabdospongia) , others cylindrical, with a 

 central cloaca (Bonneyia) , some again are cup-shajjed {Hylospongia) , 

 others massive and lobose [Acanthoplioj-a), while some are branching, 

 and others, finally, are incrusting. On closer examination of these 

 nodules, one is frequently rewarded by finding, on the exterior sur- 

 face, little pits of most definite characters. They are oval or cir- 

 cular in shape, and from ±" to -J^" in diameter. Their circumference 

 is often depressed into a concave border, across which pass regular 

 striations, frilling it like the milled edge of a coin ; sometimes these 

 groovelets cease at the outer border of the little pit, at others they 

 pass across it and wander for a long way until they are lost in the 

 surrounding surface. The general character of these pits is strik- 



-ingly suggestive of sponge oscules ; still more so is their arrangement. 

 Frequently they are grouped in sieve-like patches, sometimes they 

 occur on one side only of the nodule, and occasionally they are 



, terminal ; in all these respects they find close parallels among exist- 

 ing sponges. 



Besides these osculiform pits are numerous minute punctse, which, 

 in the Gault Coprolites, are seen to be the distinctly open termina- 

 tions of fine canals. In the Greensand forms, however, these canals 

 have become filled up since the nodules were washed out from the 

 Gault, and their openings consequently appear as mere specks of a 

 lighter colour than the surrounding substance. In other fossil 

 sponges minute openings similar to these would be called "pores" 

 by Palajonlologists. These are all the observations one can make 

 without the aid of instruments, but all the characters we have so far 

 noted agree essentially with those of sponges, and not with any- 

 thing else. 



It now becomes necessary to examine the Coprolites more in 

 detail — in sections and solutions under the microscope. When I 

 came to do this, the necessity for preparing an extensive series of 

 sections at once presented itself as a difficulty. Mr. Bonney, how- 



1 Quart. Journ. Geol. Soc. Lond., Eev. 0. Fisher, vol. xxix., p. 52 ; and "W. J. 

 SoUas, vol. xxviii., p. 397, and vol. xxix., p. 76. 



