64 
of North Britain.* Two species of the genus Maclurea are 
known, together with their opercula—the Maclurea Peachu and 
the Maclurea Logani. These are so well drawn and described 
in the Proceedings of the Geological Society of London, that I 
will only give the reference—(see vol. xv., p. 379, and plate xiii.) 
The preservation of the opercula of these species of Maclurea 
evidently depended on their hard, coarse, shelly structure. In 
appearance they are not unlike a grotesque unrolled Pileopsis. 
Leaving paleeozoic species on one side, an instructive illustration | 
may be added of the use to which an acquaintance with the 
opercula of Gastropods may be turned; and the case will 
probably have additional interest for us from the situation being 
in Liassic strata. In the Upper Lias at May and Curcy, in 
Normandy, certain strange ellipsoid fossils were not unfre- 
quently brought to light from the Leptena band. These small 
peculiar things defied all the ingenuity of the MM. Eupzs- 
Drstonecuames to decipher. All their paleontological friends 
to whom they submitted them were equally at fault. Not only 
could the Professors not refer them to any genus, but scarcely 
to their order in the Natural Kingdom. Wearied at length, and 
with exhausted patience, MM. Huprs-DEsLonecuamps thought 
it would be well to name and describe these fossils provisionally, 
in their treatise on the Upper Lias; so they gave them rank as 
a genus under the name of Peltarion, which next they divided 
into two species, standing as follows :— 
Genus PELTARION.—EUDES-DESLONGCHAMPS. 
| Peltarion unilobatum, Eudes-Desl. 
, 
Peltarion bilobatum, Eudes-Desl. \ May and Cuca 
Species . 
Of these quasi species full descriptions and figures and many 
* It isa point of interest to note here a remarkable extension of the 
range of this peculiar Silurian genus that the Challenger Expedition 
naturalists have ascertained. Captain FEILDEN, R.N., has brought home 
Maclurea from Bessels Bay, a latitude as far north as 81° 6’. (Quarterly 
Journal Geological Society, vol. xxxiv. page 804.) This important addition 
swells the list of British fossils included in the Arctic Province ; for though 
an ‘‘aberrant” form, it helps to conduct us to a more precise knowledge of 
glacial relations and periods. 
