408 BRITISH PALAXOZOIC FOSSILS. [Bracntopopa. 
under the lens. Length six and half lines, proportional width 4, depth of free valve =, distance of apex from 
posterior margin *.. 
Position and Locality—Common in the upper part of the carboniferous limestone of Derbyshire; more 
rare in the dark carboniferous limestone of Lowick, Northumberland. 
8rd Family. TEREBRATULID&. 
Arms fleshy, attached throughout their length to an internal shelly framework, bent in a double loop and 
attached to the beak of the entering (small) valve, they are incapable of protrusion beyond the shell, but pro- 
vided with short fleshy fimbrize ; texture of the shell punctured. ‘Two pairs of muscles arise from each valve; 
in the small valve the anterior pair small, oval, arise close to the central septum, and a little behind the middle of 
the length their tendons converge below the stomach, and again dilate and pass into the pedicle; the posterior 
pair arise from a small depression close to the beak on each side of the central rostral tooth. In the large valve 
the two pairs of muscles are so approximate as to form only one pair of moderate oval impressions ; the posterior 
pair go.to be inserted into the pedicle, and the anterior pair are inserted into the prominent beak of the small 
valve, and by their action open the valves. The mouth is behind the base of the arms, opening towards the 
cavity of the large valve; the cesophagus extends towards the small valve, suddenly dilates into a pear-shaped 
stomach, from the sides of which the hepatic follicles branch, forming a large green liver on each side; the 
intestine curves back towards the large valve, and making a slight bend forward, terminates between the lobes 
of the mantle on the right side. 
This family is divided into the following genera: Ist, Terebratula (Llwyd) ; 2nd, Delthyridea* ; 8rd, Tere- 
brirostra; 4th, Fissirostra ; 5th, Seminula (M°Coy). 
Genus. SEMINULA (A/*Coy). 1844. 
Ref. = Epithyris (King) not of Phillips. 
Gen. Char.—Ovate ; a large oval perforation on the beak of the receiving valve, separated from the hinge- 
line by a portion of the valve, but apparently without deltidium ; dental lamellee strongly developed in beak of 
receiving valve, slightly diverging; entering valve with a faint trace of mesial septum, and two cardinal teeth, 
from whence a small loop, with a very short recurved portion, arises ; substance of the shell punctured, usually 
without plaits. 
I originally proposed this genus, and gave a diagram of it in my Synopsis of the Carboniferous Fossils of 
Ireland, for “the Paleozoic Terebratulw, having the beak perforated by a foramen distinct from the hinge-line, 
but without a deltidium,” and naming the Terebratula seminula of Phillips, as the type (which see). Subse- 
quent observations have enabled me to extend the genus much farther than I at first expected, particularly 
when I perceived that the punctured texture of the shell would help to distinguish the species from the 
so-called Atrype (Cliothyris of Phillips) when the beaks were broken. Lately, Professor King has given 
much excellent information on the genus in his volume on the Permian Fossils of England, under the name 
Epithyris of Phillips, and pointed out the valuable and easily ascertained character of the strong dental 
lamellz: in the beak, bordering the foramen. From the observations on the middle of page 54 of Phillips’s 
Paleozoic Fossils, it is obvious, however, that Hpithyris was intended for the oolitie Terebratula, congeneric 
with the 7. mawillata, having distinct deltidium, &c. The dental lamelle leave slits in the beak of the casts, 
one on each side of the foramen, which are very characteristic of the genus, and in some states of exfoliation of 
the shell are likely to be confounded with edges of a deltidium; indeed, the appearance thus produced in 
many specimens is so puzzling, that I prefer leaving the existence or non-existence of a deltidium an open 
question ; the genus being well distinguished meanwhile from the more recent Terebratule by the rostrum being 
tripartite, from the extension of the dental lamellee, &c. This generic type seems confined to the Palzeozoic rocks. 
* This Genus was briefly characterised and figured in my Synopsis of the Carboniferous Fossils of Ireland in 
1844, and is equivalent to the subsequently formed genus Zerebratella of d’Orbigny. 
