196 Brady— On Involutina Liassica. 
described and figured under the names respectively of Involutina 
silicea, Terq., and Involutina Jonest, Terq. & Piet. The first 
of these seems to be Trochammina incerta, d’Orb. sp., a very 
variable species, not uncommon in the Lower Lias, though sel- 
dom showing the septa so regularly or so completely developed 
as they are given in the figure. To the character indicated by 
the specific name ‘stlicea, appended to the description, but 
little importance need be attached; for, though the original 
shell-substance is calcareous, the amount of siliceous sand em- 
bedded in it may easily be sufficient to preserve the form of the 
shell even after it has been treated with strong acid. The latter, 
Involutina Jonesi, is the little shell to which Professor Jones 
had previously given the name Nummutlites liassicus; but, as I 
have shown that it is not in any respect a Nummulite, it must 
bear the generic name assigned to it by M. Terquem. 
I have as yet met with the species only in the Lower Lias, 
The specimens vary in size from =; down to +5 of an inch in 
diameter. 
I cannot close this notice without acknowledging the kind 
assistance I have received from my friend Mr. W. K. Parker, 
F.Z.S8., whose many suggestions have been invaluable in de- 
termining the history of the little organism which has formed 
the subject of the present notice. 
EXPLANATION OF PLATE IX. 
Fig. 1. Involutina Wiassica, Rupert Jones sp. Large specimen from the Lias 
Shale near Rugby, Warwickshire; side-view; magnified 33 diam. 
2. Similar specimen from the same locality; end-view; magnified 33 
diam. 
. Young specimen, out of Lias Clay from Defford, Worcestershire ; 
magnified 53 diam. 
Specimen from the same locality, having the exogenous deposit 
covering the entire shell; magnified 33 diam. 
Transverse section, in a piece of the rock of Fretherne Cliff, Glou- 
cestershire; magnified 44 diam. 
6. Horizontal section of a specimen from Worcestershire, showing 
irregular septation and indications of pseudopodial perforations 
on the inner surface of the shell-wall; magnified 44 diam. 
me 09 
Or 
II. Descriptions oF some New Patmozoic CrusTacra. 
By Henry Woopwarp, F.G.S., F.Z.S. 
[Plate X.] 
EK are indebted to Mr. David Page for having first pointed 
out two very well marked genera of Paleozoic Crustacea 
of the family Hurypteride, namely, Slimonia and Stylonurus. 
I gave a description of Slimonia in the ‘ Intellectual Observer’ 
