200 H. Woodward—Descriptions of New Paleozoic Crustacea. 
4, EKuryprerus Brewstert. (Powrie MS.) Sp. nov. 
Jee Dy ites, oe 
This new species of Hurypterus was obtained by the Rev. 
Henry Brewster, of Farnell, near Brechin, from the Old Red 
Sandstone of Kelly Den, near Arbroath, and it has been named 
after its discoverer by Mr. Powrie. 
Tt consists of a carapace and a portion of the Ist thoracic segment, 
slightly displaced; close to which is seen an ovisac, in which are more 
than 20 ova, more or less compressed (fig. 3, @). 
The carapace measures 2 inches 2 lines in breadth at its posterior 
border, and 2 of an inch in length. The sides curve rapidly inwards, 
leaving the front border only 8 lines broad. The eyes, which are 1 
line in length, are reniform, and within the anterior half of the cara- 
pace; they are 4 lines apart, and have their convex surfaces directed 
outwards. The margin of the carapace is slightly striated; and 
there is an inner elevated border in front, 1 line in breadth, which 
thins out and disappears on the lateral border. The surface of the 
carapace is slightly wrinkled, but not ornamented in any way. 
This species agrees most nearly in general form with Eury- 
pterus lacustris of Harlan,* from the Upper Silurian of New 
York; but the relative proportions differ considerably. 
Interesting as this carapace is, it is rendered still more so by 
the ovisac associated with it. The so-called Parka decipiens 
may include many widely-different organisms; but I fully be- 
lieve that the oviform bodies from the Old Red Sandstone are 
chiefly the eggs of Crustacea. 
EXPLANATION OF PLATE X. 
Fig. 1. Stylonurus Logant, sp. nov. From Logan-Water, Lanarkshire.. 
Fig. 2. Pterygotus minor, sp.nov. From Farnell, Forfarshire. 
Fig. 3. Eurypterus Brewsteri, Powrie MS. sp. nov.; a, Egg-bag. From Kelly 
Den, near Arbroath, Forfarshire. 
All three specimens are in the collection of Mr. James Powrie, F.G.S8., and 
are figured of the natural size. : 
IlJ. On ter Laurentian Formation.| By J. J. Biassy, M.D., 
¥F.G.S.—Parr II. Tue Restpuary ELEMENTS oF LIFE IN THE 
LAURENTIAN GROUP. 
HE Laurentian Group is as complex in its composition as the 
younger fossiliferous metamorphic rocks ; silica, alumina, lime, 
and carbon compose its beds, together with phosphorus, fluor, barytes, 
&c.; and it develops the same accidental minerals—staurotide, gar- 
net, pyroxene, metallic compounds, &c. Why then should there not 
be in it the buried forms of life? It is found that, as we descend 
in the great sedimentary column, the organic remains gradually lose 
* See Hall’s ‘ Paleeontology of New York,’ p. 407, pl. 81, fig. 3. 
+ Continued from p. 158. 
