part 4] C'AMBKIAN HORIZONS OF COMLEY. 337 



Dimensions of type-specimens. — Lengths = 5 and 7'5 mm. ; 

 widths = 7 - l and 925 mm. ; heights = 2 and 25 mm. 



Locality and horizon. — The Cwms sub-area of Comley ; 

 from the conglomeratic beds at the base of the Obolella-c/roomi 

 Beds, horizon Ab,. 



Walcottina eleyata, sp. nov. (PI. XXI, figs. 20 ct-e, & 22.) 



Cobbold, 1916. Rep. Brit. Assoc. 1915 (Manchester), p. 118, ' brachiopod allied 

 to both Michwitzia and Kutorgina.' 



The type-specimens consist of an exfoliated fragment [1914] 

 disclosing about half of a ventral valve and its counterpart [1916]. 

 Another specimen [2282]. a sandy internal cast of a complete shell 

 in rotten stone, is used to supplement the description. 



Diagnosis. — Ventral valve : general form elevated; outline an 

 elongate oval, slightly flattened at the posterior margin, length 

 rather greater than width ; lateral angles well rounded ; convexity 

 high, highest point situated at about a quarter of the length from 

 the apex ; apex recurved, and projecting but little beyond the 

 posterior margin ; shell-substance corneous, and composed of three 

 principal layers, marked as in TV. lapivortlii, except that the 

 radiating corrugations of the inner layer do not extend so far 

 forwards, and that traces of the external concentric bands are seen 

 upon the interior layer near the anterior margin ; pedicle-opening 

 represented by an upward arching of the posterior margin (see 

 PI. XXI, fig. 22). 



Dimensions of the type-specimen [1914]. — Length = 4 mm., 

 width = 4 mm., height =3 '75 mm.; and of specimen [2282], length 

 = 7 mm., width = 6 "9 mm., height=4'5 mm. 



Dorsal valve ("?). Associated on the same little piece of rock 

 with the type-specimen are two shells which from their general 

 form are regarded as_ dorsal valves, but the surfaces are not suffi- 

 ciently well preserved to prove that the sculpture was similar to 

 that above described for the ventral valve. 



The outline is that of a sector of a circle greater than a semi- 

 circle, the two radii forming a notched posterior margin ; the apex 

 projects prominently upwards ; the anterior and lateral slopes fall 

 steeply from it, then become horizontal or even concave, and 

 finally fall again to the margin ; the posterior angles are rounded ; 

 the surfaces show concentric lineation, and the dimensions are 

 such as to correspond with those of the type-specimen. 



Observations. — The attenuation of the apex of the ventral 

 valve (fig. 20 a) [1914] suggests a possible pedicle-tube, especially 

 when compared with figs. 20 b & 20 c, which represent the exterior 

 of the same individual, but the former is a representation of the 

 interior layer of shell, not an internal cast. The exterior layer of 

 shell was evidently considerably thickened at the apical part of the 

 valve. The arching upwards of the posterior margin shown in 

 fig. 22 [2282] indicates the more probable position of the pedicle- 

 opening. 



This species is distinguished from TValcottina lapwortlii by the 



