114 
THE GEOLOaiST. 
smooth space, after wliich there exists a toh^rably regular row of lengtliencd 
tuberelcs, or slender shining tubular spines, and again, below these, the re- 
niairmig space is tilled up by irregularly scattered, but closely packed smaller 
spines ; all, however, overlap each other, and lie so close to the valve that 
none of the surface of the living shell could be perceived. In the dorsal valve 
the bands are slightly concave, but the same arrangement of the spines is ob- 
servable.* The shell in this species appears to have been thin, so that it can- 
not be easily detached perfect from hard Umcstone matrix, but from certain 
shales weathered specimens can be collected with all their spiny investment 
completely preserved. The interior of both valves have been found. In the 
dorsal one, the cardinal process is very peculiar in shape, and bilobed, but the 
nmscular and reniform impressions do not differ materially from those of other 
species of the genus. In the ventral valve, however, the occlusor impressions 
extended much lower in the vidve than those attributable to the divaricator 
muscle, and thus differ from what we obsei"ve to have been the case in P. 
gicjuntpus, P. seniireticiilaiiis, and other species. 
The shell under description attains sometimes larger proportions than have 
done auy of the Scottish examples that have come under my direct observation. 
A specimen from Ayrshhe has measured two inches and a-half in length by 
nearly two inches in width. 
Product us punctatits is not a rare Scottish fossil. It occurs at Langshaw 
Burn, in Lanarkshire, at tiiree hunched and forty three fathoms below the 
" EU coal," three hundred and seventy-five at Nclliicld, and foxir himdred and 
ten at Nellfield Burn ; also at Brockley, near Lesmahago. In Beiifrewshire, 
at Howood, near Paisley ; Barrhead- and Ardcn-quarry, Tlioriiliebauk. In 
Dumbartonshire, at Castlecary. In Ayrshire, at Iloughwood and "West Broad- 
stone, Beith ; Auehcuskeigh, Dahy ; Golderaig, Kilwkming ; Cessnoek and 
Netheraewton, parish of Galston. In Stirlingshire, at Craigenglen, Mill Bum, 
the Campsie nuuu-limestone and ironstone, and Corrie Burn. It has also been 
found in the island of Arran and in Bute, as well as in the Lothians and Fife. 
XXXV. — PaoDUCTUs fimbriatus. J. de C. Sowerby. PL ii., fig. 27. 
Prodiicfa fimhriata, J. de C. Sowerby, Miu. Con., vol. v., p. 85, pi. ccccHx., 
fig. 1, 1823. Prodiidiis fimhriatiis, De Koninck, Monographie du Gem-e 
Produetus, pi. xii., fig. 3. 
This is a much smaller species than the preceding one, rarely exceeding an 
inch and a-quarter in length by something less in breadth : its shape is longi- 
tudinally oval, or ovate, the hinge-line being a httle shorter than the greatest 
width of the shell. The ventral valve is very gibbous and greatly arched in 
profile, with its beak much incurved, and regularly vaulted, the extremity 
being attenuated, and overlying the hinge-line of the opposite valve ; the ears 
are small and but slightly marked. The dorsal valve is either nearly flat, or 
but very slightly concave. As in P. punriafus, the surface of the valves are 
externally covered with numerous sub-regular, concentric, prominent, bands, 
which are ui general more separate than in the preceding species. No example 
I have hitherto seen possessed its outer shell and spiny mvestment in any thing 
like a perfect condition, but a fragment tolerably well preseiwed has led me to 
conclude that the arrangement of the tubular spines did not materially differ 
from that of Prodadus pundatus for there evidently chd exist some smaller 
spines under the row of larger ones, but which alone seem to have left 
* In 1793, David lire gave us a very good description of this shell ; he states that both 
valves are covered with small spines resembling hair, and so numerous that a largish example 
contains upwards of ten thousand ; and that they lie so closely together that the surface of 
the shell is entirely concealed from view. 
