Vol. 58.] REFERRED TO MURCHISONIA AND PLEUROIOMARIA. 317 
different families contained in the suborders Sinuata, Koken and 
Eotomacea, Ulv. respectively. 
From what has been stated with reference to the investigations 
of Prof. Koken and Messrs. Ulrich & Scofield, it is evident that 
the earliest appearance of true Murchisonie still remains to be 
traced. In the lists of so-called Murchisonice several distinct genera 
are associated with them, and they consequently require revision. 
Mr. Etheridge’ records twenty-four British species of Proterozoic 
Murchisonia. Four of these, as I have shown, probably belong to the 
genus Hormotoma : namely, H. articulata, H. cingulata, H.(?) dubia 
(referred to as MW. bellicincta, Hall), and H.(?) gracillima (MM. gracihs, 
Hall, var.). The specimen described as MW. angustata, Hall, was 
placed by Salter in the genus Hormotoma, but I have pointed 
out * that it bears more resemblance to Hctomaria; it is, how- 
ever, in too poor a state of preservation to admit of accurate 
determination. J. scalaris, Salt., too, is so bad a cast that it is 
impossible to discern its actual structure. Other species, again, 
must be excluded, as though they possess a band, and in some cases 
a slit, their characteristics agree more with those of Lophospira 
and some of the genera into which the original genus Plewrotomaria 
has been divided. Such fossils are—M. angulata, Sow., M. balteata, 
Phill., WZ. cancellatula, M‘Coy, M. corpulenta, Sollas, M. gyrogonia, 
M‘Coy, M. inflata, M‘Coy, M. Lloydii, Sow., M. pulchra, M‘Coy, 
M. simplex, M‘Coy, M. subrotundata, Portl., MM. sulcata, M‘Coy 
(which is identical with J. Lloydiw, Sow.), and MW. turrita, Portl. 
The six species which remain are—WM. angulocineta, Salt., Md. bi- 
cincta, M‘Coy, M. coralli, Sow., M. elegans, Sollas, M. obscura, 
Portl., and M. torquata, M‘Coy. Although the general form of 
M. angulocincta somewhat resembles that of Murchisonia, I feel 
doubtful as to whether it really is a member of that genus; for the 
lines of growth, though not very distinct, seem merely to indicate 
a notch. It should probably be referred to the Cicelia subsection 
of the Perangulata section of the genus Lophospira, Whitfield. The 
other five species, and three new ones which I am about to describe, 
resemble Murchisona in the band being grooved, and bounded on 
each side by a keel or raised thread, and also in the direction of the 
lines of growth. But none of the specimens of these species that 
J have seen have the outer lip intact, or the lines of growth suffi- 
ciently well preserved to show whether they possessed a slit or not. 
As a rule they are more slender than Murchisonia, and, with the 
exception of MV. elegans, the whorls are more convex. In this latter 
characteristic they resemble Hormotoma, but the lines of growth are 
less oblique and the spiral ornamentation is more marked. MV. elegans 
comes nearer to the description of Goniosiropha, Ckhl. than to 
that of any other section or subgenus of Murchisonia, and it seems 
advisable to place it there at present. The others, however, do not 
appear to agree with any previously described division of the 
1 «Foss. Brit. Is.” vol. 1 (Paleozoic) 1888, p. 118, 
* Quart. Journ. Geol. Soe. vol. lv (1899) p. 259. 
