830 ME. E. S. COBBOLD 0> T THE [vol. Ixxvi, 



The lengths of the Comley specimens range from 4 to 5 

 millimetres, the ratio of length to width is about 1 to 1'3, and that 

 of length to height about 1 to 33. 



Several of the best-preserved specimens are in the collection 

 made by Mr. Rhodes for H.M. Geological Survey. 



Locality and horizon. — Lower Cambrian. The Cwms. 

 sub-area of Comley and also west of Comley Quarry ; from the 

 Obolella-c/roomi Beds, horizon Ab r 



Miceomitea (Pateeina) ehobesi, sp. nov. (PI. XXI, figs. 4 a- 

 4 c, 5, G, &?9.) 



Type-specimen [PR 1473], Geological Survey collection. 



Diagnosis. — Ventral valve: outline nearly semicircular, with 

 lateral angles sharp, and inclined to be alate ; greatest width at the 

 posterior margin ; convexity moderate, anterior and lateral slopes 

 straight; apex marginal, pointed and somewhat erect; false area in- 

 clined a little forwards; pseudodeltidium triangular, gently convex, 

 wide, angle made by its bounding sides about 120°, marked by two 

 pairs of radiating angular lines so as to be polygonal in horizontal 

 section ; line of flexure from lateral slopes of shell to false area very 

 abrupt and transverse to the axial line ; free posterior margin of 

 pseudodeltidium arched upwards ; shell-substance corneous and 

 very thick, built up of many lamina? ; surface marked by irregular 

 concentric ridges which pass round the lateral angles to the false 

 area, and are traceable across the pseudodeltidium. 



Remarks. — There are a few radiating ridges on the central 

 part of the test in one specimen [PR 1476]. Several specimens 

 have the surface adventitiously indented in many places. 



Dimensions in millimetres: — 



TRR 1473] [RR 1470] [RR 1471] 



Length ? 6-0 5'5 



Width 8-75 9-25 8-0 



Height 1-6 14 1-4 



The species is chiefly distinguished by its abrupt flexure-line, its 

 polygonal pseudodeltidium (fig. 4 b), and by being widest at the 

 posterior border. 



For comparison with other species, see p. 331. 



Locality and horizon. — Comley. Lower Cambrian; from 

 the mottled (conglomeratic) and greenish-grey beds of the Road 

 Quarry in the Cwms sub-area, horizon Ab t . 



Dorsal valve (11 g. 9). The exfoliated test fRR 146o] has a 

 very prominent vertical apex, and is regarded as a dorsal valve. 

 It is found on the same piece of rock with an external cast referred 

 to M. pMllipsi, and may belong to tbat species ; but its general 

 outline is more suggestive of M. rhodesi. 



S3 V 



Miceomitea (Pateeijsta) kexgi, sp. nov. (PI. XXI, figs. 7 & 

 8a-8b.) 



Type-specimen [King 2], Geological Survey collection. 



