162 
CONCHIFERA. 
Avicula. 
26. Avicula modioliformb. —The Modiolaforined Avicula, 
pi. LXVI.* fig. 19. 
A. modiola. Rhind, Age of the Earth, p. 167, pi- 2, fig. 5. 
Much elongated transversely; innhones placed near one 
side, gradually widening towards the opposite side ; hinge-line 
not defined, a triangular small car on one side; surface trans¬ 
versely wrinkled. 
The Coal Shale, Woodhall, on the River Leith, near Edin¬ 
burgh. 
27. Avicula novemcostae. —The Nine-Ribbed Avicula, 
pi. LXVI.** fig. 12. 
A. inwquicalvis . Phillips, Geo. York, I. p. 133, pi. 14, 
fig. 4. 
Oblirpiely oval; hinge-lino slightly oblique; one ear very 
small, the other largo ; surface smooth, with nine longitudinal 
rounded, divergent ribs, gradually thickening from the beaks to 
the basal margin. 
The Marlstone, in many localities. 
28. Avicula expansa. —The Expanded Avicula, pi. 
LXVI.** fig. 13. 
A. expansa . Phillips, Geo. York, I. pi. 3, fig. 35. 
Oblong-ovate, very oblique ; the posterior side extremely 
produced; anterior side short and gently curved; auricles 
well defined, very unequal; the anterior one very small, and 
the posterior one largo, curved on the side ; hinge-line a little 
oblique; surface smooth, with about sixteen rounded, divergent, 
longitudinal ribs. 
The Coral Rag, Mai ton, the Kelloways Rock, South Cove, 
and Oxford Clay, Scarborough. 
29. Avicula ovalis. —The Oval Avicula, LXVI.** 
fig. 14. 
A. ocalis . Phillips, Geo. York, I. pi. 3, fig. 36. 
Oblong-ovate ; ears unequal, the anterior one about half the 
size of the other ; hinge-line considerably oblique and straight; 
beaks produced; sides a little unequal, gently rounded ; sur¬ 
face with numerous, divergent, shallow, longitudinal furrows, 
and a few concentric, shallow lines of growth. 
The Coral Rag, Yorkshire. 
30. Avicula deckpta. — The Deceptive Avicula, pi. 
LXXXIII. fig. 18. 
Obliquely transverse; hinge-lino nearly straight; auricles 
undefined ; the anterior one acute; lower part of the dorsal 
side produced; umbones obsolete; surface transversely 
wrinkled. 
The Coal Shale, Vale of Todmorden. 
31. Anomia gryphoides. —The Graphite Avicula, pi. 
LXVI.** fig. 19, 20. 
A. giyphoides, Sowerby, Geo. Tr. 2d Scr. IV. p. 335, pi. 
11, fig. 3. 
Obliquely elongated; the convex valve ovate, with a pro¬ 
duced, incurved beak, and two small nearly equal auricles; 
upper valve nearly flat, suborbieular, and furnished with a 
single auricle. 
The Upper Greensand, near Petorsfield. 
o J. A v icula elegantissima. —The Very Elegant Avicula, 
pi. LXVI.** fig. 21. 
A. edeyantussinm. Phillips, Geo. York, I. pi. 4, fig. 2. 
Transversely elongated ; its breadth twice and a half its 
length; hinge-line a little hollowed; beaks produced, large. 
rounded, and situato near the anterior side, which is extremely 
short, and almost straight; posterior side much elongated, 
with a large auricle, nearly equal to half the breadth of the 
shell; surface smooth, and provided with from seven to nine 
divergent, longitudinal, smooth ribs in the centre of the 
valves. 
The Coral Rag, Malton. 
33. Avicula radiata. —The Rayed Avicula, pi. LXVI.** 
fig. 30. 
A. radiata. Phillips, Geo. York, II. p. 211, pi. 6, fig. 8. 
Sub-orbicular ; hinge-line straight; beaks nearly central ; 
auricles unequal, acute, and extending beyond the sides of the 
valves; surface with many radiating, rather broad ribs, and 
narrow intervening furrows ; base rounded. 
The Carboniferous Limestone, Bolland. 
34. Avicula cycloptera.— The Cyclops Avicula, pi. 
LXVI.** fig. 34. 
A. cycloptera. Phillips, Geo. York, II. p. 211, pi. 6, fig. 5. 
Sub-quadrangular; hinge-line sloping downwards from both 
sides of the beak ; sides a little conical; surface smooth, with 
four or five radiating ridges, arising a little below the beaks, 
and terminating on the rounded and scolloped basal margin ; 
lines of growth slightly imbricated on the disk of the valves. 
The Carboniferous Limestone, Bolland. 
35. Avicula tessellata. —The Tessellated Avicula, pi. 
LXVI.** fig. 31. 
A. tessellatta. Phillips, Geo. York, II. p. 211, pi. 6, lig. 6. 
Sub-quadrangular; hinge-line slightly curving downwards 
from the beak, and extending beyond the sides; auricles very 
large, unequal, and subacute ; surface with from eight to fif¬ 
teen radiating rounded ridges, extending beyond the basal 
margin, producing a scolloped edge. 
The Carboniferous Limestone, Bolland and Colster Dale. 
36. Avicula sublobata. —The llalf-lobod Avicula, pi. 
LXVI.** fig. 32. 
A. sublobata. Phillips, Geo. York, II. p. 211, pi. 6, 
fig. 25. 
Oval, slightly oblique; hinge-line short, straight, with a 
small auricle on one sido; surface with numerous divergent, 
flat, narrow ribs, the intermediate furrows with flue concentric 
stria). 
The Carboniferous Limestone, Castlctou, Derbyshire. 
37. Avicula Bramburiensis. —The Brambury Avicula, 
pi. LXVI.** fig. 33. 
A. BramburienMs. Phillips, Geo. York, I. pi. 6, fig. 6. 
Ovate, slightly oblique; hinge-line oblique, auricles a little 
unequal ; surface with many longitudinal, divergent ribs, 
which are furnished with numerous imbricated scales; basal 
margin a little scolloped; beaks obtuse, extending a trifle 
beyond the hinge-lino. 
The Great Oolite, Cloughton and Brora. 
3S. Avicula Modiolaris. —The Modiola-liko Avicula, 
pi. LXI.** figs. 23, 24. 
A. modiolaris. Sowerby, Geo. Tr. 2d Ser. V. pi. 39, fig. 18. 
Obliquely and transversely elongated ; compressed; keeled 
towards the beaks; auricles undefined; hinge-line straight. 
The Coal Measures, Coalbrook Dale. m 
39 Avicula quadrata.— The Squarish Avicula pi. 
LXI.** 27, 28. 
