DAVIDSON — SCOTTISH CAEBONIFEROUS BRACHIOPODA. 113 



sMi'e it occurs in the Mill Burn beds, and in the Campsie main-limestone. In 

 Dumbartonshire, in the Castlecary limestone. 



XXXITI. — Productus scabriculus. Martin. PL iv., fig. 18. 



Anomifes scabriculus, Martin, Petrif. Derb., pi. xxxvi., fig. 5, 1809. Productus, 

 Sowerby, Min. Con., vol. i., pi. clvii., pi. Ixix., fig. 1. 



This shell is margmally rotundate-quadrate, and somewhat wider than long, 

 the ventral valve being convex, with small flattened auriculate expansions, and 

 a wide, but slightly deepened mesial depression, or sinus ; the hinge-line is 

 either shorter, or as long as the width of the shell, while the dorsal valve 

 becomes slightly concave, with a small median elevation, or fold, apparent only 

 in the vicinity of the frontal margin. The surface of the larger valve is closely 

 covered with numerous subregular striae swelling out at close intervals in the 

 shape of oblong tubercles, arranged somewhat irregularly in qumcunx, and 

 from which project short curved spines ; the valves are likewise at times feebly 

 concentrically wrinkled, and the surface of the dorsal valve is marked with 

 numerous small elongate, oval, tubercle-pits. 



1 am not acquainted with any good interiors of this species ; all 1 know of 

 the dorsal valve is derived from an internal cast m ironstone, from Jock's Burn, 

 in the parish of Carluke, and which shows that the cardinal process was bi- 

 lobed, and that a small median ridge extended from its base to a little more 

 than half the length of the shell, the muscular and remform impressions were 

 very faintly marked, but appear to be similar to those of Troductus punctatus. 

 The largest Scottish examples with which I am acquainted measured fifteen 

 lines in length by sixteen in width, but the shell has attained much larger 

 dimensions in the neigbourhood of Dairy. 



P. scabriculus is plentiful in ironstone, at Jock's Burn, in Lanarkshire, at 

 three hundred fathoms below the " Ell coal," three hundred and seventy-five at 

 Braidwood and Hill Head, in the parish of Carluke, at Brockley, near Lesma- 

 hago, and Robroyston and Moodies Burn north of Glasgow. In Stirlingshire it 

 occurs in several stages, such as the Craigenglen beds, Campsie main-limestone 

 and ironstone, and Corrie Burn. In Benfrewshire, at Barrhead; Ho wood, near 

 Paisley ; and Arden-quarry, Thornliebank. In Dumbartonshire at Castlecary. 

 In Ayrshire, at Auchenskeigh, Dairy ; and West Broadstone, Beith. It has 

 also been found in Pifeshire and in the Lothians. 



XXXIV. — ^Productus punctatus. Martin. PI. iv., fig. 20-22. 



Ammites punctatus, Martin, Petrif. Derb., p. 8, pi. xxxvii., fig. 6., 1809. Pro- 

 ductus, De Koninck, Monograpliie du Genre Productus, pi. xii., fig. 2 = P. 

 elegans, M'Coy, etc. 



The shells of which this species is composed vary somewhat in shape from 

 being transverse, or slightly elongated; all are, however, more or less 

 rotundate-quadrate, with a hinge-line shorter than the greatest width of the shell, 

 the auriculate expansions being flattened, but not always clearly defined. The 

 ventral valve is moderately convex, with a wide longitudinal sinus, commencing 

 at a short distance from the extremity of the beak, this last being small and 

 incurved. The dorsal valve is but moderately concave, with a very slight 

 mesial elevation, which commences at about the middle of the valve and ex- 

 tends to the front. The surface of the valves are externally covered with 

 numerous sub-regular concentric bands, or ridges of growth, which increase in 

 number and breadth as they recede from the extremity of the beak and hinge- 

 line, but in very adult shells they again become closer and closer as they ap- 

 proach the margin. These bands (in the ventral valve) are slightly raised to- 

 wards their lower margin, and are abruptly separated from each other by a narrow 

 VOL. III. P 



