2 THE ENTOMOSTRACA OF 



detritus" of Charing, Kent. For specimens of the Detritus, and for a fine suite of its 

 Microzoa, I am indebted to Mr. Harris, of Charing.^ To Mr. Morris I am indebted 

 for his kind assistance in working out the history and characters of the Entomostraca, 

 and for specimens of the foreign Cretaceous rocks, so necessary for comparison. 

 I have also to acknowledge the courtesy and kindness shown me by Dr. Baird, 

 who has favoured me with much valuable information on the subject of the recent 

 Entomostraca. 



The earliest notice of the occurrence of Entomostraca in the Enghsh Chalk is 

 given in Sir C. Lyell's ' Anniversary Address' for 1836 (Geol. Proc, vol. ii, p. 365), and 

 subsequently in the ' Elements of Geology' (1838, p. 55); a single valve of a Cytherella 

 being there figured with other Microzoa obtained by Mr. Lonsdale from the Soft Chalk. 



In M. Roemer's work, ' On the Cretaceous Formation of North Germany,'" seven 

 species of Entomostraca are figured and described, and in Dr, Reuss's work, ' On the 

 Bohemian Chalk,'^ seventeen species. M. Cornuel'' has figured and described eight 

 species with their varieties from the Neocomian formation of France, M. Bosquet" 

 twenty species from the Maestricht beds, and Mr. Williamson" has given figures of five 

 species from the Charing Detritus, with provisional names. 



There is much confusion in the nomenclature of these species, arising from the 

 imperfect descriptions and not very clear figures of MM. Roemer and Reuss, whilst 

 MM. Cornuel and Bosquet have renamed certain species already noticed by the 

 former. Altogether thirty-eight distinct and seven doubtful species belonging to the 

 Cretaceous system have been hitherto noticed. 



Each of the above-mentioned writers, with the exception of M. Cornuel, has made 



^ Mr. Harris has obliged me with the following description of the character and locality of the 

 " Detritus." The .village of Charing stands on a bank of " chalk-detritus," composed of fragments of 

 white and grey chalk, which gradually decrease in size from blocks of one or two feet in diameter, lying at 

 the top, to very minute fragments, succeeded by still finer particles forming a clay-bed, which, in general' 

 reposes on the Chlorite-marl (Glaucouite). This bank extends from the southern escarpment of the 

 adjacent hills, which form part of the northern boundary of the Weald of Kent, in a gradual descent south- 

 ward for more than half a mile, where a hollow is formed occupying an area of about fifteen acres, and 

 surrounded by chalk-detritus, except at one point, where a rivulet carries off the streams from the chalk- 

 hiUs. In this hollow beneath the vegetable soil, and also under the banks of detritus, lies the clay-bed 

 above mentioned, varying from one to twelve feet in depth, of a greyish colour and tough consistence, and 

 containing nodules of undecomposed white and grey chalk and of ochreous and argillaceous substances. 

 This bed abounds with many varieties of Amorphozoa, Zoophyta, Annelida, Polythalamia, and Entomostraca, 

 with fragments of several species of other Crustacea and of Echinodermata, and with many specimens of 

 Couchifera, Brachiopoda, and Cephalopoda ; also with bones, teeth, and scales of fish. From its general 

 and palseontological characters, this bed would seem to have been formed from the washings of the neigh- 

 bouring chalk-hills at the time they received their present undulated contour. — W. H. 



2 Verstein. Norddeutsch. Kreidebirg. 1840. ^ Verstein. Bohm. Kreideform. 1845. 



* Mem. Soc. Geol. de France, 2" ser., tom. i, p. 193, 1846; torn, iii, p. 241, 1848. 



5 Descript. Entom. foss. Maestricht. 1847. ^ Memoir on some Microscopical Objects, &c. 1847. 



