DAVIDSON — SCOTI'ISU OAUIlONlKliHOlJS UKACIIIUI'ODA. 
473 
almost equally (lo(^p, with a wide mesial deiircssiou towards tlie front in the 
larger number of individuals. The beak, is moderately produeed, and but 
slif,ditly ineurved ; the foramen is rather large, oval, and in adult shells approxi- 
mates io the und)one of the smaller valve. The external surfaee is smooth, 
markcxl oidy by a f(!\v concentrie lin('s of growth, and the intimate shell-struc- 
ture is minutely perforated by small punctures, which may be easily detected 
on all specimens of which the sliell has not been affected by mctamorpluc action. 
In the Ulterior of the ventral valve there exists two short diverging dental or 
rostral shelly plates, wliile in the interior of the dorsal one a short simple 
loop is observed, occupying about one-third of the length of the valve, as iu 
Lign. fig. 3. 
Tereiratula hasiaia was ornamented with stripes, 
in all probability of a red colour, similar to that 
still found on several of the recent forms ; but it 
is rare to find colour-markuigs preserved on the 
surfaee of palaeozoic shells ; some examples in 
England and in Ireland have been found to be thus 
ornamented, and one was recently discovered in 
Scotland by Mr. J. Young. 
Scottish examples of tliis shell do not appear to 
have been so numerous as, or to have attained the 
dimensions of some of, those that have been found 
in England and Ireland. The largest individual 
that I have hitherto seen is from the last-named 
country, and is in the possession of Dr. Bower- 
bank ; it measures 26^ lines in length by 19 in 
Lign. 3.— TEEEBRATULA HASTATA. brcadth and 13 in width. 
Interior of dorsal valve. hadata occurs at about 375 fathoms below the 
Ell-coal at Nellfield and Braidwood, and at 391 
fathoms at Braidwood Gill, in the parish of Carluke ; it is fomid also at Capel 
Eig, East Kilbride, eight miles S.S.E. from Glasgow ; also at Calderside and 
Auchentibber, High Blautyre, and Brockley, near Lesmahago, in Lanarkshu'c. 
In Renfrewshire it occurs at Arden quarry, near Thoriilie Bank, four miles south 
from Glasgow. In Stirlingshire it may be collected from the Craigengleu beds, 
the main limestone, and Corrie Burn beds. In Ayrshire, at Craigie, near 
Kilmarnock, at Aucheuskeigh, near Dah-y, and West Broadstone, near Beith. 
In Filesliii'e, at Liniekibs.* 
II. — Terebrattjla saccules. Martin, sp. PI. xii., figs. 3, 4. 
CoHchi/liolithus anomites sacculus, Martin. Petreficata Derbiensia, tab. xlvi., 
figs. 1-2, 1809 ; and Dav. Mon. Garb., p. 14, pi. i., figs. 23, 24, 27, 29, 30. 
Shell ovate, or somewhat pentagonal in shape ; notched and emarginated in 
front, smooth ; valves nearly equally convex, with a slight depression near the 
front in the dorsal valve, and a rather deep mesial furrow in the ventral one. 
T. sacculm does not appear to attain the dimensions of T. hastata ; and is, 
comparatively speaking, much more convex. Martin states that "the form of 
the shell is purse-like, its margin blunt, hollowed out opposite the beak by an 
obtuse indentation, which is sometunes continued along the back of the 
beaked valve in the shape of a slight hollow furrow or wave." That last- 
* In order to avoid unnecessary repetitions, I may here mention that most of the specimens 
from Lanarkshii-e were kindly communicated by Mi-. Armstrong, Mr. Beimie, Dr. Slimon, 
and a ft-iend in Carluke. Those from Stirlingshii-e by Mr. Yomig. The Renfrewshire, Dum- 
bartonshire, and Ayrshire specimens were lent by Messrs. J. Thompson and J. Armstrong, 
wliile those from the Lothians and Fifesbire were communicated to me some years ago by 
Dr. Fleming, H. Miller, etc. 
