380 BRITISH PALAXOZOIC FOSSILS. [Bracuiopopa. 
6th Family. UNCITID. 
This family was originally proposed by d’Orbigny for Uncites, Atrypa and Pentamerus ; but as I propose to 
restrict it to the one genus, Uncites, the generic and family characters are given together, the latter being rather 
different from those of d’Orbigny, and no previous careful description of the genus having been published so far 
as I know. 
Genus. UNCITES (Defrance) as here defined. 
Gen. Char.—Shell elongate, ovate, slightly inequilateral; substance very thick, densely fibrous; beak of 
receiving valve very long, narrow, claw-shaped, gently incurved obliquely to one side, with a wide, concave, 
imperforate defined channel beneath ; no internal septa, nor appendages, in either valve. 
Uncites ta&vis (Coy). Pl. 2. A. fig. 6. 
Sp. Ch.—Longitudinally ovate, oblique; entering valve, when young, ovate, moderately convex, with the 
front and lateral margins broadly rounded; when old becoming very gibbous and subrhomboidal, from the con- 
vergence of the sides to a narrow rounded front; receiving valve obtusely subcarinate along the middle when 
old, by the nearly flat sloping of the sides; the front margin not perceptibly elevated, and the lateral margins 
nearly horizontal ; beak very large, sharply pointed, and widely-arched inwards obliquely to one side, the under 
part of the beak widely channelled, with obtusely angular or rounded lateral margins ; surface smooth, or only 
marked by the concentric lines or imbrications of growth towards the margin. Length of receiving valve two and 
half inches, proportional length of entering valve 4, width =, depth of both valves =; thickness of shell in beak 
of receiving valve two lines, above the beak of entering valve on one side five lines, on the other side four lines, 
diminishing the cavity to two lines in diameter; thickness of shell about the middle of the sides of receiving and 
entering valves three lines, diminishing to little more than one line along the middle, and gradually thinning to 
the margins. Length of young specimen nine lines; proportional length of entering valve {;, width %, depth of 
both valves =. 
The general narrow elongate form, and the oblique torsion of the long, narrow, claw-like beak in this 
species, exactly reminds us of the Uncites gryphus of Defrance, from which it is distinguished by the absence of 
the longitudinal sulcation. Having first ascertained the true internal characters of that curious Eifel genus, it 
gave me great pleasure to recognize in our British rocks a second species of this remarkable genus. I should 
have imagined that the smadler of the two figures given in Sowerby’s Mineral Conchology, under the name of 
Terebratula porrecta, represented a young individual of this species, on account of the narrow produced front; but 
as Mr Sowerby himself has since stated (Geol. Trans. 2nd Series, Vol. V. exp. of t. 56) that those figures 
represented specimens of Stringocephalus Burtini, and as all writers seem to coincide in that opinion, I have only 
to observe, that the present fossil, by the complete absence of internal septa, and the external characters above 
enumerated, has no affinity whatever therewith. 
Position and Locality—Not uncommon in the Devonian limestone of Newton Bushel, Devonshire. 
Explanation of Figures.—P1. 2. A. fig. 6, natural size; 6a, profile of ditto; fig. 64, section of both 
valves at about one-third the length from the beak, shewing the thickness of the shell and absence of internal 
apophyses; 6c, section of beak of receiving valve, shewing the great thickness of the shell reducing the 
internal cavity, and absence of internal septa. 
7th Family. RHYNCHONELLID. See page 199. 
Genus. HEMITHYRIS (d@Orb.) See page 199. 
HEMITHYRIS ACUMINATA (Mart. Sp.) 
Ref. and Syn.= 0. A. acuminatus Mart. Pet. Derb. t. 32 and 33. f. 7 and 8.+ 0. A. pugnus id. id. t. 22. f. 4, 5. 
+ Terebratula cordiformis Sow. Min. Con. t. 495. f. 2 and 4.+ 7. platyloba id. id. t. 496. f. 5 and 6. 
+ (T. mesogona Phil. Geol. York. Vol. I. t. 12. f. 10 to 12. = Atrypa triangularis Sow. Geol. Trans. 2nd 
Series, Vol. V. t. 54. f. 9.) 
