299 
there were two new species, a Cochliodus and a Ctenacanthus. The 
plates also of a tuberculated fish, belonging either to Pterichthys or 
some allied genus, were exhibited, proving that this great class had 
passed far up into the carboniferous system. 
2. Estuarine strata, between F and L. These comprise the well- 
known Burntisland limestones, corresponding with beds west of 
Pittenweem. 
One remarkable jaw of a pycnodont fish was exhibited from this 
part of the series near Kilwinning. Only one example of this class 
of fish-remains had previously occurred in the whole Palaeozoic sys- 
tem — a small jaw found near Leeds. 
3. The limestone L, the line of Lower Encrinites. This occurs 
east of Pittenweem, at Crail and St Andrews. The fossils were de- 
scribed similar as a whole to those of the beds A F. 
Forty species of fossil shells occurring in these rocks were enu- 
merated, only twelve of which are given in Professor Nicol’s list of 
Scottish fossils. Among those here added, were Sanguinolites tri- 
costatus, , Chemnitzia gracilis, Murchisonia trilineata, &c. &c. 
Section IV. Lower Carboniferous. This great underlying series 
was described in its leading features, especially — 1. The Myalina 
beds — limestones composed of a single bivalve allied to Unio. 2. 
The deep-sea character of the fossils found at different levels, spe- 
cies of Orthoceras, Natica, Lingula, &c. 3. A limestone charged 
with great abundance of a new annelid, a species of Spirorbis, beau- 
tifully curved in a serpentine form. 
Section V. Results. The two groups. 
The writer explained that he had been led to deviate from the 
usually received classification of these rocks. Taking the upper 
portion of what Mr Maclaren terms the calciferous sandstones down 
as far as the bed L, and adding these to the upper zone, usually 
called the Mountain Limestone, two well-marked groups would be 
formed, and a well-defined line of division obtained. 
1 . The Mountain Limestone. The bed L, containing the same 
fossils with the six upper limestones, must (notwithstanding the in- 
tervening Estuarine beds) be classed along with them, and forms 
the base line of the upper group. The whole strata, from A to L, 
are approximately about 1000 feet in thickness. The limit upwards 
was not examined. The fossils all belong to the Mountain Lime- 
stone, and are extremely characteristic. 
