LOWER LUDLOW GROUP. 161 
Luptow RocKxs.—Lower Division. 
Not easily distinguishable, except by their superposition and fossils, from the Wenlock rocks. The mineral 
character, shale and limestone, is much, of course, like that of the underlying Wenlock limestone and_ shale. 
And of course, also, many of the organic remains are alike. A great many of them are corals, bryozoa, and 
brachiopod and cephalopod shells, which have considerable range. But there is no practical difficulty at all in 
recognizing Ludlow from Wenlock by the fossils. It is very easy; and it is the business of the scientific 
geologist to neglect the common terms, and study the real and abiding differences which constitute the claim 
of one set of rocks to be called distinct from another. Moreover, the Ludlow is distinct from the Wenlock 
in Sweden; and the Lower Helderberg series of America (N.) are the exact equivalents of our Lower and 
Upper Ludlow rocks, as the Niagara group is of the Wenlock formation. 
I include the Aymestry with the Lower Ludlow, as one is only a calcareous condition of the other. And 
Mr Lightbody of Ludlow has already laid stress on the fact (Quart. Geol. Journ. Vol. 19, p. 368) that the calca- 
reous nature of the beds above the Aymestry rock influences the fossils to a marked degree; so that, were it 
possible, it would be better to draw the line “Upper Ludlow” only at some distance above the Aymestry rock. 
Even in districts where the Aymestry is absent, the Lower and Upper Ludlow rocks are recognizable; 
though not easily separable by a hard line. (J. W. Salter, from personal survey.) 
Lower LupLow Rock AND AYMESTRY LIMESTONE. 

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a ) - 
Galewn 6 2 EES a LB OOES Names and References; Observations, &c. Numbers and Localities. 
Drawers. Synopsis : and Figures of Genera. . 
PLANTA. 
Gel Sponges. Spongarium Edwardsii, Murch. (Silu- | b. 2, Dinas Bran, Llangol- 
ria, 2nd ed. pl. 12, fig. 3). len. 
AMORPHOZOA. 
?New flat sponge with radiating | See Bryozoa. 
fibres. Shape cylindro-conical, two 
inches long. 
HYDROZOA 
(BRYOZOA or POLYZOA.) 
Gel G. ludensis, p. 4. | Graptolithus priodon, Bronn. (Leth. | b. 850, Garden Quarry, 
Geogn. t. 1, fig. 13). Aymestry. 
Gel Ce Pry, Graptolithus priodon, G. ludensis, var. | b.851,Leintwardine, Shrop- 
GET E) minor, McCoy, p. 5. shire. 
| Gel sae Graptolithus, sp. b. 852, Underbarrow, Ken- 
; dal. 
Gel Dendrograpsus, Hall. 
Gel | | Dendrograpsus, sp. Nicholson, Quart. | b. 853, Leintwardine. 
| "9 | Journ. Geol. Soc. 
