257 
On a small and new Pltyllopod Crustacean. 
place of the various graptolitiferous deposits of Europe and 
America; and, basing his argument on his intimate knowledge 
of their included and peculiar forms, he endeavours to trace 
out the progress of the several genera and species, both in 
space and time. He infers that the evidences at his com¬ 
mand show that the Skiddaw forms migrated southwards and 
westwards into Wales, Ireland, and America. Four species 
emigrated northwards into the Moffat area of the south of 
Scotland. This Moffat area became subsequently the birth¬ 
place of the genera Retiolites , Ccenograptus , Rastrites , and, 
most probably, Pleurograptus and Monograptus. It formed 
in its turn a grand centre of dispersion. To the south it fur¬ 
nished 55 per cent, of the later Coniston-Mudstone fauna. 
Its western emigrants, after peopling the Caradoc beds of the 
south of Ireland, crossed what is now the Atlantic, and reap¬ 
peared in great force in the Utica Slates and Lorraine Shales 
at the summit of the Ordovician of New York and Canada. 
Easterly the course of the Moffat forms can be even more 
satisfactorily followed, their first resting-place being the 
Greywacke area of Saxony, whence they subsequently passed 
southwards into Barrande’s Colonies and the band E e 1 of 
the Bohemian Basin. 
[To be continued.] 
XXIX.— On the Occurrence of a small and new Pliyllopod 
Crustacean , referable to the Genus Leaia, in the Lower 
Carboniferous Rochs of the Edinburgh Neighbourhood. By 
Ii. Etheridge, Jun., F.G.S., of the British Museum. 
The rapid increase in the number of invertebrate species 
lately discovered in the Calciferous Sandstone or Lower Car¬ 
boniferous rocks of the south-east of Scotland, through the 
researches of the Geological Survey and of private collectors, 
has in a great measure tended to bridge over the gap which 
was formerly supposed to exist between the two important 
subdivisions of the Carboniferous system in Scotland—the 
Calciferous Sandstone series and the Carboniferous Limestone. 
In continuing this subject* it is with much pleasure that I 
have to chronicle the discovery, by Mr. James Bennie, of a 
* “ On our Present Knowledge of the Invertebrate Fauna of the 
Lower Carboniferous, or Calciferous Sandstone Serbs, of the Edinburgh 
Neighbourhood, especially of that Division known as the Wardie Shales,” 
Quart. Journ. Geol. Soc. 1878, xxxiv. p. 1. 
