114 



THE GEOLOGIST. 



smooth space, after whicli there exists a tolerably regular row of lengthened 

 tubercles, or slender shining tubular spines, and again, below these, the re- 

 maining space is filled up by irregularly scattered, but closely packed smaller 

 spijies^ 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 limestone 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 

 muscular 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 valve than those attributable to the divaricator 

 muscle, and thus differ from what we observe to have been the case ia P, 

 gifjantev.fi, T. semireticulahcs, and other species. 



The shell under description attains sometimes larger proportions than have 

 done any of the Scottish examples that have come under my direct observation. 

 A specimen from Ayrsliire has measured two inches and a-half in length by 

 nearly two inches in width. 



P/Yy^///,'7//.v pimdatus is not a rare Scottish fossil. It occurs at Langshaw 

 Burn, iu L:i iuirkshire, at three hundred and forty -three fathoms below the 

 *' EU coal," three hundred and seventy-five at Nellfield, and four hundred and 

 ten at Nellfield Burn ; also at Brockley, near Lesmahago. In Benfrewshire, 

 at Ilowood, near Paisley; Barrhead- and Arden-quaiTy, Thoruliebank. In 

 Dumbartonshne, at Castiecary. In Ayrshire, at Roughwood and West Broad- 

 stone, Beith ; Auchenskeigh, Daky ; Goldcraig, KiLwuming ; Cessnock and 

 Ncthornewton, parish of Galston. In Stirlingshire, at Craigenglen, Mill Bui-n, 

 the Campsie main-Kmestone and ironstone, and Corrie Burn. It has also been 

 found in the island of Arran and ia Bute, as weU as in the Lothians and Eife. 



XXXV. — Productus fimbriatus. J. de C. Sowerby. PI. ii., fig. 27. 



Frofhicfa f mbriata, J. de C. Sowerby, Miu. Con., vol. v., p. 85, pi. ccccHx., 

 lig. 1, 1823. 'Productus fimhriatus, De Koninck, Monographic du Geni-e 

 Productus, pi. xii., fig. 3. 



This is a much smaller species than the precediag one, rarely exceeding au 

 inch and a-q\iartcr in length by something less in breadth : its shape is longi- 

 tudinally oval, or ovate, the hinge-line being a little shorter than the greatest 

 width of i he shell. The ventral valve is very gibbous and greatly arched in 

 )rn(ilc, with its beak much incurved, and regularly vaulted, the extremity 

 )cing 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 

 ))iit very slightly concave. As in P. pundatns, the siu-face of the valves are 

 externally covered with numerous sub-regular, concentric, prominent, bands, 

 which arc in general more separate than in the preceding species. iS'o example 

 1 have hitJuM-lo seen possessed its (Mitcr shell and spiny investment in anything 

 like a perfect condition, but a iVauineut tolerably well' preserved has led me to 

 eonehuU« that the arrangement of the tubular spines did not materially differ 

 from that of Prod itcf /ix pinicfdf its for there evidently did exist some smaller 

 spnu's undm- the row of larger ones, but which alone seem to have left 



In 17n:i. Dnvul Urc frnve us a verj- crood description of this shell ; he states that both 

 \-ftlyo8 are covered with small spines resemblin£r hau-, and so numerous that alai-£^ish example 

 wnuvuis np\mrda of ton thousand ; and that tliey he so closely together that the surface of 

 the i»hcn Ks cnLiifiy coucealod from view. 



