470 ME. F. CHAPMAN ON THE [Aug. rSg6 r 



chalk, that the concentration of the phosphoric acid was the work- 

 of small fishes, is strengthened by the fact that the remains of such 

 animals are still more abundant in the Southerham chalk. 



The deposits seem to have some connexion with hard nodular 

 floors which are believed to mark changes or pauses in the sedimen- 

 tation, accompanied by contemporaneous concretionary action. 

 Though presenting points of similarity with phosphatized Globi- 

 gerina-ooze, they are not pelagic deposits. 1 



The same cause which delayed the sedimentation (whether change 

 of current or otherwise) seems occasionally to have led to the 

 assembling of multitudes of small fishes, but rather by providing 

 them with food than by causing their destruction. 



Appendix by F. Chapman, Esq., A.L.S., F.K.M.S. 

 The Foeaminipeea and Osteacoda. 



• The following notes and accompanying list are the result of an 

 examination — (1) of some unweathered phosphatic chalk, which 

 was crushed and levigated ; (2) of about fifteen mounts of specimens 

 selected by Mr. J. Bennie, together with other specimens which I 

 obtained from similar material, and which had been taken from a 

 weathered surface of the same phosphatic band. 



The foraminifera and ostracoda from each of the samples differed 

 so materially from one another in their general f acies that it seemed 

 advisable to keep the two lists separate. One noteworthy difference 

 is the occurrence of six species of ostracoda in sample 2, and only 

 one species in sample 1. There is also a predominance of arena- 

 ceous forms in sample 1, mainly belonging to the Textulariidae ; 

 while the members of the Lagenidse largely obtain in sample 2. 

 This latter, along with the occurrence of the ostracoda, points to 

 the shallower condition of the water for sample 2. 



The foraminifera are, with few exceptions, either entirely phos- 

 phatized, or they are infilled with phosphate of lime. This is 

 clearly seen by examining material which has been treated with 

 weak acetic acid, some of the specimens retaining their usual out- 

 line and superficial markings, while others are represented only by 

 the form of the chamber-cavities of the shell, and have the delicate 

 stolon-passages preserved in relief by the infilling process. 



The f oraminiferal facies of the Southerham chalk appears to differ 

 very essentially from that of the phosphatic chalk of Taplow, 2 but it 

 agrees exactly with the fact of its being on a lower horizon than 

 the latter rock, since there is a noticeable scarcity of truly Upper 

 Chalk forms in the material under discussion. 



Forty-two species and varieties of foraminifera and six species of 



1 [In reading the paper I used here the expression ' shallow water' in place 

 of ' not pelagic' This did not, however, convey the meaning I intended, and' 

 led to an apparent difference of opinion in the discussion. — May 15th, 1896.] 



2 F. Chapman, Quart. Journ. G-eol. Soc. vol. xlviii. (1892) p. 514. 



