74 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
not uncommon, show that it often grew over the surface of dead shells, forming 
a basal stratum, out of which rose up, here and there, a few plume-like 
branches. Of the two specimens represented under fig. 10 a, the slender one 
appears to have attached itself to the inside of a Mytilus squamosus , and the 
other to the outside of another shell. The specimen figured at 10 b shows 
very distinctly the arrangement of the tubes, as displayed on a longitudinal 
section magnified. 
None of the specimens exhibit the transverse plates and septal foramina cha¬ 
racteristic of the genus, as represented in pi. iii., fig. 6, of my Monograph, 
which is to be regretted; inasmuch as some additional evidence seems to be 
required to prove that the species belongs to the genus Favosites. Messrs. 
Edwards and Haime consider it to belong to Chsetetes. 
Favosites MacJcrothii is rather common in the Permians of Durham and 
Germany. 
3. Thamniscus dubius = Keratophytes dubius, Schlotheim. —PI. i., fig. 11; Mono¬ 
graph, pl. v., figs. 7-12. 
A single fragment, little more than a quarter of an inch in length, is all that I 
have found of this Hornera-like fossil; but it is distinct enough to enable 
me to make the present identification. The genus Thamniscus is a low, irre¬ 
gularly-branching Bryozoon, the branches of which bifurcate irregularly: 
they are celluliferous on one side; while the other consists of a plate serving as 
a base for the cellules. In the species under consideration, the cellules are 
arranged in rows, of which there are from three to six on the branches. The 
Tullyconnel specimen is a portion of a branch, apparently divided at one (the 
upper) end, and exhibiting casts of three rows of cellules. Thamniscus dubius 
occurs in the Permians of Durham and Germany. 
4. Mytilus squamosus, J. de C. Sowerby. —PI. 1., figs. 3 a, and 36 ; Monograph, 
pl. xiv., figs. 1-7. 
This fossil might at first glance be considered as having a close resemblance to 
some small varieties of the common mussel of our coasts; it is, however, very 
distinct, being inequivalved, having a widish furrow for the reception of the 
cartilage, and a septum in the umbonal cavity of both valves. The last cha¬ 
racter is always exhibited in good casts, which show an impression of it at the 
anterior termination of the hinge, as in fig. 3 a. The specimen referred to 
shows the posterior adductor muscular impressions, and a portion of the 
pallial scar. Some specimens are wider than others; but all the varieties may 
be easily distinguished from another Permian species—the Mytilus septifer 
—apparently only found in the North of England. 
This fossil is abundant in the Tullyconnel magnesian limestone: some of the 
stones in the front wall of Mr. Slorne’s house are crowded with specimens, many 
of which are an inch and a half long, the largest I have seen. It is a character¬ 
istic species of the Permian rocks of England (Durham), Germany, and Petchora 
land in Russia. 
5. Bakevellia antiqua = Avicula antiqua , Munster. —Pl. i., figs. 4 a, b, c, d; Mo¬ 
nograph, pl. xiv., figs. 28-34. 
