452 F. R. Cowper Reed- — Fossils from Haverfordivest. 



the Wenlock Limestone; and our specimens, wliich come from the 

 Slade Beds near St. Martin's Cemetery, Haverfordwest, show the 

 typical characters. It has been found in the Chair of Kildare 

 Limestone, but apparently has not previously been recorded from the 

 Bala of South Wales. It seems to be in both cases a rare species. 



Zygospika Hicksi, sp. nov, (PI. XXIII, Figs. 17-19.) 



Description. — Shell subcircular or ovoid, subglobose, biconvex. 

 Pedicle valve larger than brachial, strongly convex, occasionally 

 with faint traces of median fold ; beak incurved. Brachial valve 

 less convex ; beak small, overlapped by that of pedicle valve ; weak 

 median depression sometimes present on surface of valve. Interior 

 of pedicle valve with stout, short teeth widely separated ; small 

 transverse ridge from tooth to tooth; elongated, subparallel, muscular 

 impressions extending nearly half the length of valve and broadening 

 slightly anteriorly, with low ridge between them ; no dental lamellse. 

 Interior of brachial valve with hinge-plate, broad, stout, and cleft 

 in middle into two triangular portions ; low median rounded ridge 

 dividing paired impressions of adductors. Surface of valves orna- 

 mented with 25-30 simple, straight, rounded, radiating ribs of equal 

 size, without bifurcation or intercalation of shorter ribs ; regular, 

 fine, concentric strise present. 



Dimensions. 



Length ... ... ... ... 10 mm. 



Width 9-75-10 mm. 



Localities. — Cuckoo Grove Lane, Haverfordwest ; Upper Slade. 



Horizon. — Slade Beds. 



Remarks. — This interesting shell appears to belong to the genus 

 Zygospira (or perhaps its subgenus Catazyga), for though we are 

 ignorant of much of its internal structure, and have not seen its 

 brachial spires, yet in its shape, ornamentation, and internal 

 characters, so far as they are known to us, it closely resembles 

 members of this genus. Zygospira is known in the British Lower 

 Palaeozoic by the form referred by Davidson to Atrypa (?) Headi, 

 var. anglica} There does not seem to be any very marked line of 

 separation between Zygospira and Catazyga, which Schuchert employs 

 as a generic name ; Hall,^ for instance, considers Z. anticostiensis to 

 be intermediate between them. The smaller specimens of this Slade 

 shell in our collection are of a more elongated and ovoid shape, but 

 otherwise appear to be identical with the larger subcircular form. 

 Z. Headi, var. anglica, differs from our species in having more 

 numerous (forty or more) ribs which are also finer, and in having 

 the muscle-scars in the pedicle valve slightly difierent ; and on the 

 whole it seems to belong to another species. 



Hyattella pkntagonalis, Keed (?). (Plate XXIII, Fig. 20.) 

 The muscular impressions of JS^. pentagonalis ^ are unknown, but 



1 Davidson: op. cit., vol. iii, pi. xxii, figs. 1-8 ; suppL, vol. v, p. 127. 



2 Hall & Clarke: Paltcont. New York, vol. viii, Brach., pt. 2, pp. 154-159. 

 ^ Reed: Quart. Journ. Gaol. See, vol. liii (1897), pp. 75-77. 



