Vol. 67.] ASSOCIATED ROCKS OF tfORTH-ElST MONTGOMERYSHIRE. 455 



CrRTOLiTES parvus Ulrich, var. carinatus nov. (PI. XXXVI, 

 fig. 17.) 



This pretty little fossil corresponds closely with Ulrich's species. 1 

 It differs, however, in having a distinct and well-defined keel, 

 which is absent in the type-specimen. This is so well-marked a 

 feature that I have named the Welsh variety carinatus. 



Horizon and locality. — Trilobite-Dingle Shales, Penbryn 

 Dingle. 



(4) Brachiopoda (Inarticulata). 

 Lingula obtusiformis, sp. nov. (PI. XXXVI, figs. 18 & 19.) 



The two specimens figured are respectively 7 and 4*8 millimetres 

 long, and 5 and 3-6 mm. broad. 



Shell almost oval in shape, narrowing slightly at the beak. 

 Almost flat, very slightly raised on the umbones. .Beak not placed 

 at the extreme posterior border as in most species of Lingida, but 

 completely surrounded by the margin of the shell. The posterior 

 portion of the valve is bisected by a strong median septum. The 

 surface of the shell is covered with strong concentric ridges, parallel 

 with the margin and sometimes showing stronger lines of growth. 

 In addition to the concentric ridges, radial striae also occur. 



This species corresponds most closely with L. obtusa of Hall 2 ; 

 but the ribbings are much more pronounced, and the median 

 septum is not seen in that species. It has also apparently some 

 affinity to L. coburgensis of Billings. 3 The characters of the shell 

 seem to be sufficiently distinct to warrant the formation of a new 

 species ; and, because of the close relationship to L. obtusa, I propose 

 to call this species Lingula obtusiformis. 



Horizon and locality. — Gwern-y-brain Shales, Guilsfield. 



(5) Corals. 



Streptelasma (?) aff. ereve Ulrich. (PI. XXXVI, figs. 20 & 21.) 



Height = 18 millimetres ; width across cup = 26 mm. Corallum 

 free, simple, conical, slightly curved, and expanding very rapidly. 

 Width greater than height. Surface marked with strong annulations 

 and rather pronounced vertical ribs. Calyx deeply concave, extend- 

 ing to about a third of the height from the rim of the corallum. 

 Septa large and small : total number of septa = about 72. The septa 

 reach to the centre of the calyx, but the internal structure is 

 not seen. The species is very like Streptelasma breve Ulrich, 4 but 

 is larger, straighter, and possesses a more shallow calyx. 



Horizon and locality. — Powis-Castle Beds, Powis Park. 



1 ' Geology of Minnesota' Geol. Nat. Hist. Surv. Minn. vol. iii, pt. 2 (1897) 

 p. 864 & pi. lxii, figs. 45-47. 



2 ' Palaeontology of New York ' vol. i (1847) p. 98 & pi. xxx, figs. 7 a-7 c 



3 'Palaeozoic Fossils' Geol. Surv. Canada, vol. i (1861-65) p. 50, fig.£54; 

 ' Geologyof Canada ' Kep. Progr. Geol. Surv. Can. 1863, p. 161 & fig. 132. m m Z.. 



4 ' Geology of Minnesota' Geol. Nat. Hist. Surv. Minn. vol. iii, pt. i (1895) 

 pp. 92&93, figs. *t ar-td. 



