Preropopa. | LOWER PALALOZOIC MOLLUSCA. 287 
the ovarium and testis are both large, and both terminate at an opening on the right side of the head. 
Some genera have no cephalic tentacles, others have two for touch and groups (sometimes thousands) of 
prehensile suckers. Some are blind, others have a small eye at the base of each tentacle. Some are naked, 
others are provided with a thin hyaline shell, of one or more pieces; when of two pieces one is dorsal, the 
other ventral. 
Genus. THECA (Sow.) 
Ref—ld. Morris, in Strzelecki, N. S. Wales. 
Gen. Char.—Shell straight, short, rapidly tapering to a point; monothalamous ; section, and opening tri- 
angular; surface transversely or longitudinally striated. 
Tueca Forsesi (Sharp). 
ef-—Geol. Journ. Vol. IT. t. 13. f. 1. 
Sp. Ch.—Margins of flat sides, converging at an angle of about 19°; surface marked with coarse trans- 
verse lines, more than their thickness apart, and close strive; section nearly an equilateral triangle; mesial 
ridge slightly rounded, about 92°; average length about nine lines, width of mouth about three lines. 
This seems identical, so far as can ibs satieed from the figure of Hall, with the American 7. triangularis, 
which is not however the Orthoceras (Theca) triangulare of Portlock, which latter is a much larger and more 
slowly tapering species. 
Position and Locality —Not uncommon in the Upper Ludlow of Lambrigg Fell, Kendal, Westmoreland : 
and in the olive schists of Dinas Bran, Llangollen, Denbighshire. 
Genus. CONULARIA (Miil.) 
Ref—Sow. Min. Con. Vol. IIT. p. 107. 
Gen. Chav.—Shell thin, short, pyramidal, four-sided, each side bounded by a deep longitudinal sulcus, 
transversely marked with ridge-like plicee; each face usually divided by a longitudinal impressed line. 
The small end seems not to taper to a point, but each face ends in a small rounded lobe* I follow 
the general impression in placing the Conulariw with the Pteropoda. It is very unfortunate that in the 
original article in the Min. Con., giving the first descriptions and figures of these fossils, that at least two 
species belonging to different geological systems should have been classed under the one name C. quadri- 
sulcata, a specific name which recalls a character common to all the genus as now restricted, and is therefore 
not in itself desirable ; but when to this we add the confusion of opinion among authors as to whether the 
carboniferous or Silurian specimen should bear this name, the greater number agreeing to confine that name 
to the carboniferous species, although a reference to the description and principal figure (4) would shew that 
it ought more properly perhaps to be applied to the Silurian one, I think it is the only satisfactory plan to 
follow the specific nomenclature of Sandberger, in his excellent Monograph in Leonhard and Bronn, Neues 
Jahrbuch for 1847, and renounce entirely the name guadrisulcata, and the still more indefinite one (Sowerby?), 
which M. Defrance chose to apply to Sowerby’s figure. 
CONULARIA CANCELLATA (Sandberger). 
Ref. and Syn.—Leonh. and Bronn, Jahrbuch, 1847, p. 20. t. 1. f. 11. 
= C. quadrisulcata Sow. Sil. Syst. t. 12. f. 22. 
Sp. Ch.—Depressed, sides of each face converging at about 20°; the four faces equal, each divided by a 
faint longitudinal furrow, usually rather nearer the outer or marginal sulcus than the inner one, but varying in 
this respect, and sometimes partially obsolete ; transverse plicee bent upwards at an angle of about 130° near 
the apex, 135° in the middle, and upwards of 140°, or only slightly arched towards the mouth; usually continuous 
across each face, meeting the sides at a more acute angle than the medial suture; about five in the space 
