CYMBULARTA CARINATA. 65 



expanded, broadly triangular, with basal angles projecting laterally. Slit-band 

 situated on slightly elevated compressed keel. Surface of shell smooth? 



Dimensions. — Height of shell [6655] c. 8 mm. 



Horizon. — Upper Ludlow (Passage Beds). 



Localities. — Horeb Chapel [6655]; Bradnor Bill; S. of Trichrug, Llangadock 

 [28097—28090] ? 



Remarks. — The type-specimen [6655] from Horeb Chapel in the Jermyn Street 

 Museum is an imperfect internal east partly embedded in matrix, but showing the 

 umbilicus on one side. Only internal easts of the speeies are known, Sowerby's 

 original description is brief and runs as follows: " Convoluted, compressed, keeled, 

 smooth; inner whorls several, small, partly visible; aperture an equilateral 

 triangle." He also recorded the species from the Upper Ludlow of Bradnor Hill 

 (pp. cit., p. 613), but gave no figure. 



It has been often recorded from the Llandovery beds, but its occurrence in 

 them is highly doubtful, the specimens thus labelled in the Jermyn Street and 

 British Museums from Bog Mine, Shelve, Eastnor Park and Llandovery appa- 

 rently belonging to a variety or even another species (see next page). 



In spite of the opinion of many palaeontologists that B. carinatus is identical 

 with II. acutus, Sowerby, Salter 1 as far back as 1854 recognised that they were 

 distinct, saying: "B. acutus appears to be quite a distinct species from II. carinatus, 

 [the former] having a very acute keel and flat almost excavated sides strongly 

 striated; the umbilicus is very large and sharp-edged." We may also add that 

 the inflation of l>. carinatus is marked, and the mouth is transverse and broad, 

 overhanging the umbilicus, instead of high and narrow. It is not improbable that 

 two species from the Upper Ludlow rocks have also been associated under the 

 name B. carinatus, the narrow lenticular much compressed form with the very 

 acute angular dorsum, very small umbilicus and large outer whorl, such as Nos. 

 28098 and 28099 in the Jermyn Street Museum, being distinct from the type and 

 perhaps belonging to Zouidiscus or another genus. 



McCoy (oj). cit.) united J I. carinatus and B. acutus " with no doubt of their 

 identity," and consequently his definition of the former applies strictly to neither 

 species; the only localities and horizons which he mentions are the Tilestone 

 (Ludlow) of Storm Hill, Llandeilo, and the " calcareous Upper Bala schists of 

 Dolydd Ceiriog Waterfall, S.E. of Moel Ferna, E. of the Berwyn Mountains," the 

 latter locality furnishing 11. acutus. 



Moberg and Grim wall- remark that B. lenticularis, Gronwall, from the Wenlock 

 rocks of Gotland, is allied to //. carinatus, Sow., and to B. acutus, Sow. Koken 3 

 described a shell of Ordovician age as Cymbularia lenticularis which is distinct 



1 Salter, ' Quart. Journ. G-eol. Soc.,' vol. x (1854), p. 74. 



2 Moberg and Gronwall, op. cit., p. 43, pi. iii, figs. 12 a, b. 



3 Koken, ' G-astrop. bait. Untersilurs,' p. 116, fig. 3. 



