CYMBULARIA YOUNGI. , '» , » 



not reflexed; upper lip with wide open V-shaped sinus followed by short narrow 

 slit. Slit-band narrow, strongly margined Surface of shell ornamented with 

 fine regular equal closely-placed thread-like lines arching back suddenly near slit- 

 band to meet it at about 20°— 30°. A few low narrow rounded equidistant 

 transverse folds are usually present on the sides near the mouth. 



Dimensions.— Height of shell, c. 1<> mm.; width of outer whorl behind mouth, 

 c. 11 mm. 



Horizon. — Llandovery Group. 



Locality. — (1) Gas Works, Haverfordwest; The Frolic, Haverfordwest; (2) 

 ? Blaen-y-cwm. 



Remarks. — This shell resembles II. fastigiatus, Lindstrom, 1 except in the weak 

 trilobation of the dorsum, which is also met with in some specimens of the variety 

 of G. drummuckensis above mentioned. Such a feature is found in the Devonian 

 trilobed genus Plectonotus, Clarke, which agrees in this respect with Bucaniella, 

 but possesses a slit-band. It is possible that a callosity filled up the umbilicus. 

 The specimens of C. turnbulli occur mostly as internal casts. The types are in the 

 Sedgwick Museum. 



It is probable that the poorly preserved and more or less crushed specimens 

 [28053 — 56] from the Lower Llandovery of Blaen-y-Cwm, in the Jermyn Street 

 Museum, to which the name " Bellerophon oentriculatus, Edged MS.," is attached, 

 are referable to this species, but no description or figures of specimens have ever 

 been published under this name. 



7. Cymbularia youngi, sp. nov. Plate XI, figs. 5 — 8. 



Specific Characters. — Shell lenticular, more or less com [tressed, completely 

 involute; whorls tectiform, carinate, subtriangular, higher than wide, few in 

 number, with acutely angulated dorsum. Umbilicus closed, subcentral. Mouth 

 high, triangular, much expanded, but not reflected at base, projecting laterally and 

 supported by stout horizontal callosities arising from umbilicus ; outer lip with 

 large V-shaped sinus and broadly rounded apertural" lobes. Slit-band narrow, 

 elevated in slight carina, concave, with raised edges. Surface of shell crossed by 

 fine closely-placed regular thread-like transverse lines of equal strength, arched 

 back suddenly at about two- thirds the height of whorl to meet slit-band at about 

 45°— 60°. 



Dimensions.— Height of shell, c. 22 mm. ; thickness at umbilicus, c. 11 mm. 



Horizon. — Whitehouse Group (Middle Ordovician). 



Locality. — Shalloch Mill, Girvan. 



Remarks. — This shell, though closely allied to C. drummuchensis, is rather more 

 compressed than that species; the slit-band is also borne on a more definite keel and 



1 Lindstrom, op. cit., p. 76, pi. vi, figs. 1 — 10. 



