DAVIDSOX — SCOTTISH CAEBOXirEEOrS ERACHIOPOr-A. 



473 



almost equally deep, with a wide mesial depression towards the front in the 

 larger number of individnals. The beak is moderately produced, and but 

 slightly incurved ; the foramen is rather large, oval, and in adult shells approxi- 

 mates to the umbone of the smaller valve. The external surface is smooth, 

 marked only by a few concentric lines of growth, and the intimate shell-struc- 

 ture is minutely perforated by small puncmres, which may be easily detected 

 on all specimens of which the shell has not been affected by met amorphic action. 

 Li the iaterior of the ventral valve there exists two short diverging dental or 

 rostral shelly plates, wh£e ia the interior of the dorsal one a short simple 

 loop is observed, occupying about one-third of the length of the valve, as in 

 Lign. fig. 3. ' ^ 



Terehmtida ha-stcda was ornamented with stripes, 

 ia all probability of a red colour, similar to that 

 still found on seVeral of the recent forms ; but it 

 is rare to find colour-markings preserved on the 

 surface of palaeozoic shells; some examples ia 

 England and ia Ireland have been found to be thus 

 ornamented, and one was recently discovered ia 

 Scotland by Mr. J. Young. 



Scottish examples of this 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 ia the possession of Dr. Bower- 

 bank ; it measures -26^ lines in length by 19 in 

 Lign. 3.— TiBEBBArcLA EASTATA. brcadth aud 13 ia width. 



Interior of dorsal valve. T. hast at a occurs at about 375 fathoms below the 

 EU-coal at Xellfield and Braidwood, and at 391 

 fathoms at Braidwood GDI, in the parish of Carluke ; it is found also at Capel 

 Rig, East KUbride, eisht miles S.S.E. from Glasgow ; also at Calderside and 

 Auchentibber, High Blantyre, and Brockley, near Lesmahago, in Lanarkshire. 

 In Benfrewshire it occurs at Arden quarry, near Thomlie Bank, four miles south 

 from Glasgow. In Stirlingshire it may be collected from the Craigenglen beds, 

 the main limestone, and t'orrie Bum beds. In Ayrshire, at Craigie, near 

 "Kilmarnock, at Auchenskeigh, near Dairy, and West Broadstone, near Beith. 

 In Eifeshire, at Limekil n s.* 



II. — TEREEEATriA SACcrirs. Martin, sp. PL xii., figs. 3, i. 



ConchjUoUthus anomites ■sacculu-s, Martin. Petreficata Derbiensia. tab. xlvi., 

 figs. 1-2, 1S09 ; and Dav. Mon. Carb., p. 14, pL i., figs. 23, 21, 27, 29, 30. 



Shell ovate, or somewhat pentagonal in shape ; notched and emargiaated in 

 front, smooth ; valves nearly equally convex, with a slight depression near the 

 front ia the dorsal valve, and a rather deep mesial furrow ia the ventral one. 

 T. saccidifs ^QQS not appear to attain the dimensions of I. 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 sometimes continued along the back of the 

 beaked valve ia the shape of a slight hollow furrow or wave." That last- 



* In order to avoid mrn ecessary repetitions, I may here menucn that most of the specimens 

 from Lanarkshire were kradly conrniLmicated by Atr, Armstrcng. ilr. Bennie, Dr. Slimon, 

 and a friend in Carltike. Those from Surhngshire by 3Ir. Young. The Eei:^e^5hire, Dum- 

 bartonshire, and Ayrshire specimens were lent by ilessrs. J. Thompscn and J. Armsrroiig, 

 while those from the Lorhians and Fifeshire were" commimicaied. to me some years ago by 

 Dr. Fleming, H. iMiller, etc. 



