398 PROCEEDINGS OV THE GEOLOGICAL SOCIETY. [May 22, 



matter, is generally free from incrustation. Many other examples 

 might be cited, all pointing to the intimate connexion between the 

 presence of animal matter and phosphatic deposition. The basis of 

 animal matter was derived from various sources ; the fossil remains 

 of Vertebrata, Crustacea, Echinodermata, Mollusca, and so forth 

 are coprolites the origin of which is clearly evident. But these 

 constitute only a fraction of the whole ; of the rest, the nature of 

 which has hitherto been unknown, the majority are fossil Sponges, 

 and of the minority remaining some few are formed from phospha- 

 tized animal matter decomposed so far as to have lost all traces 

 of its original structure before mineralization. In some cases this 

 animal matter may have been derived from small fish, since bones 

 and scales of fish are found in some kinds of coprolites. 



General similarity of some Coprolites to Sponge-forms. — Cylin- 

 droidal and cyathiform coprolites are abundant, consisting of a 

 central core of Chalk-marl surrounded by an outer annular portion of 

 coprolitic material, which is still impregnated -with animal matter. 

 These two parts together mark out the former existence of a hoUow 

 cylinder of animal matter, such as is exhibited in various recent 

 and fossil sponges, and, taken in conjunction with other characters, 

 seem to indicate an affinity to the Spongidse. If this be so, the 

 chalk core fills up what was once the cloaca of the sponge, and the 

 phosphatic material replaces its animal matter. Minute pits upon 

 the surface indicate the oscula. More important facts regarding this 

 and other forms will form the subject of a future communication. 

 In the Upper Chalk silicified sponges form flints, in the Upper Gault 

 phosjihatized sponges form coprolites ; thus the coprolites might 

 almost be termed the flints of the Gault. 



The Greensand consists of (1) calcareous, (2) siliceous, (3) glau- 

 conite and coprolitic granules. 



(1) Calcareous grains comprise sponge- spicules, spines and plates 

 of Eehinoderms, minute shells, shell- fragments and prisms, Polyzoa, 

 bivalve Entomostraca, microscopic corals, Foraminifera, and calca- 

 reous concretions. 



Calcareous concretions. — Kather abundant, subspherical granules 

 varying in size, generally from -Jg- to -g-L of an inch diameter, looking 

 like rounded grains of milky-white quartz or spinose Foraminifera. 

 Sections reveal a crystalline structure radiating from the centre, 

 crossed by concentric lines of growth. Centre with a nucleus 

 or not. 



Foraminifera. — TrocJiammina and Lituola very abundant ; Lagena, 

 entosolenian and ectosolenian forms ; Noclosaria, Dentalina ; Ortlioce- 

 rina, very arenaceous forms ; FroncUcularia, Vaginulina, Flahellina^ 

 Textularia, and Bulimina, verj arenaceous forms, of large size ; 

 Cuneolina, JRotalia, and Glohigerina. Numerous species of Lagena 

 occur abundantly, especially entosolenian forms : except L. apiculata, 

 recorded by Reuss in the Gault, this genus has not hitherto been 

 found below the Maestricht Chalk. 



Entomostraca. — Cytliereis quadrilatera, C. ciliata, C. tripUcata : 



