Bracuiopopa. | UPPER PAL/ZOZOIC MOLLUSCA. 463 
ferous limestone of Beith, Ayrshire; carboniferous limestone of Lowick, Northumberland ; middle limestone of 
Poolwash, Isle of Man. Var. pugilis and var. Flemingi, carboniferous shale, Berwick on Tweed; carboniferous 
shale, Glasgow. Var. pugilis, carboniferous limestone, Dent; carboniferous limestone, Dalmellington, Ayrshire ; 
coal shale, Glasgow; carboniferous limestone, Flintshire; red carboniferous limestone, Closeburn, Dumfries- 
shire. 
PRODUCTA GIGANTEA (Mart. Sp.) 
Ref. and Syn. = Anomites giganteus Martin, Pet. Derb. t. 15 =Productus giganteus Sow. Min. Con. t. 320+ 
P. latissima Sow. id. t. 8330 (Young) + P. crassa Mart. Sp. (variety with short ears) ; ?+ P. Edelburgensis 
Phill. Geol. York. t. 7. f. 5 (young of last var.) + P. Scotica Sow. Min. Con. t. 69. f. 3, and t. 561. (This 
latter plate was originally published separately by Mr Sowerby with the name P. Scotica, but was subse- 
quently given as a number of the Min. Con. as P. hemispherica, with which it is probably not identical). 
Desc.—Transversely oval; hinge-line exceeding the width of the shell, forming ears which are semi- 
elliptically pointed, flattened when young, becoming semicylindrically enrolled with age, and either passing 
gradually and conoidally into the body of the shell (P. /atissima Auct.), or more commonly separated abruptly 
from the highly inclined sides of the very gibbous body of the shell (P. gigantea Auct.), occasionally the gradual 
passage on one side, and the abrupt definition on the other, of a single specimen; body of the shell of great but 
very variable gibbosity; profile greatly arched from the beak to the front margin; beak usually very large, 
gibbous, except at the apex, and not much overhanging the hinge-line. Surface entirely covered with thick, 
obtuse, flexuous strize, dividing and anastomosing irregularly, nearly as coarse at the beak as at the front 
margin, varying from eight to thirteen in a space of three lines, the intervening sulci being usually less than the 
striz in width, all crossed by microscopic lines of growth; the general surface is even for about one inch from 
the beak of the receiving valve, beyond which there are usually a very variable number of perfectly irregular, 
fold-like, rounded ridges, increasing in strength towards the margin, commonly a little more or less than one- 
fourth of an inch wide, and separated by concave spaces about the same size; spines few or moderately 
numerous, small, but thicker than the strie, which they often interrupt and deflect, irregularly scattered. 
Entering valve almost as concave as the receiving one is convex, (greatest intervening space only two lines in a 
specimen six inches wide), and marked similarly in all respects, except a slightly flatter beak, and the longitudinal 
folds not developed till about two inches from the beak. Internal casts: receiving valve with the two bosses 
left by the large adductor impressions, finely sulecated longitudinally, moderately prominent, each rotundato- 
quadrate (in most specimens the finely suleated portion at least as long as wide, very rarely the width one-third 
greater than the length), and about their length apart; from their posterior margin, the triangular, compara- 
tively smooth, broadly suleated space (abductor impressions), extends to the beak, having between them the 
large and very complexly lobulated dendritic impressions ; in front of the adductor impressions may often be 
seen the impressions of two large, nearly circular, shallow cavities, the obtuse boundaries of which are larger 
on the outer than on the inner margin, obviously corresponding to the circularly inrolled, arm-like lobes, the 
impressions of which are seen on the opposite valve ; beyond these are traces of obscure, straight, longitudinal 
impressions of pallial vessels; internal surface beyond the visceral impressions spinulose, with sharp tubercles 
having an irregular quincuncial arrangement, falling gradually into rugged lines towards the margin ; interior of 
entering valve with a stronger septum than the other, with a large cardinal boss, the dendritic impressions more 
regular and ovate than in the other; near the end of the septum on each side a rather large, smooth, oval boss 
(Zinsertion of adductors), from the outer side of each of which a narrow, strap-shaped, smooth, impression with 
prominent edges curves outwards, forwards, and a little inwards at its rounded extremity, from which an 
obscurely-defined smoothness of the surface forms a circular continuation, probably indicating the place of the 
inrolled fimbriated arm-like lobes of the animal; beyond these the surface is spinulose. Average width seven 
inches, length in proportion to width commonly from * to = (gigantea), rarely from to (crassa), propor- 
tional depth about { in var. gigantea, varying from +, to & in var. crassa. 
The magnificent suite of this species presented by the Rev. Mr Jenkinson to Professor Sedgwick, and 
[Fase, 111.] 30 
