vine: entomostraca in the wenlock shales. 
401 
STRATAGRAPHICAL DISTRIBUTION OF THE OSTRACODA IN THE 
WENLOCK SHALES. 
(I. BuiLDWAS Beds, only.) 
1. Lower Wenlock Shale represented by the following numbers : 
Nos. 22, 37, 36, 38, 40 Buildwas Beds." 
II. Middle Wenlock Shales— No. 43. " Coalbrookdale Beds." 
III. Upper Wenlock Shales— Xos. 41, 42, 2.j. " Tickwood Beds." 
(a) Wenlock Limestone. 
IV. Shales over Wenlock Limestone — Xos. 24, 46. 
(fc) Lndlow Series. 
The materials supplied to me by ]\Ir. Maw as Washings from 
the Buildwas Beds," were in five different packages, of which Xos. 
22 and 37 were the least in bulk, and Xo. 40 the greatest. Xos. 
36 and 38 were in separate boxes about 8 inches square and G inches 
deep — Xo. 40 was nearly double this size : whilst Xos. 22 and 37 
were in very small cigar boxes. The organic debris were results of 
the washings of several tons of shale. To obtain the Ostracoda now 
given I rewashed the various packages, and in this way I got some 
really good samples of the finer clay, which, when sifted, was 
examined by the highest power of my hand-glass, and the Ostracoda 
picked out with a fine camel's hair pencil. In X^os. 22 and 37 a 
great variety of forms were obtained — but though my fine clay 
from the Xos. 36, 38 and 40 beds were more abundant than from the 
shales of the other two numbers— both individuals and species of 
Entomostraca were far less. This will be noted by referring to the 
stratagTaphical list. Associated with the Entomostraca in the shale 
debris of Xos. 22 and 37 were innumerable fragments of Trilobita 
of several species, but rarely perfect forms, so we may consider the 
debris of these two numbers in all probability as similarly characteristic, 
but I regard the Ostracoda, of all the shales below the Wenlock 
Limestone, as belonging to the age of the shale deposits, rather than 
as being derived species from any former Silurian age. I am not so 
positive about the other organisms, but even most of these seem far 
less water-worn than species from the Coalbrookdale beds. The 
Ostracoda, however, except where some of the examples are 
broken by the washings of myself and Mr. Maw, are generally perfect, 
