96 Correspondence—J. Wilfrid J uckson. 
P.S.—A recent visit to Zelau shows that there is a much greater 
outcrop of andesitic and rhyolitic rocks in that area than I had 
previously suspected. There is also an outcrop of a fresh-looking 
granite which, in the field, resembles the granite exposed in the 
big creek on the Ex-Lands road, with which Dr. Falconer is familiar. 
If this granite is shown, on more exact examination than was 
possible on a flying visit, to be of the younger series, it will be the only 
case that 1 have observed of this granite forming a small isolated 
outcrop. So far I have failed to find any indication of marginal 
cooling. 
I am informed by a mining engineer who knows the Zelau—Begindi— 
Liuri-Kano country intimately, that outcrops of “ younger ” ovanite 
do occur near to Begindi and at Liuri-Kano. At the latter place 
they are associated with rhyolites apparently similar to those at the 
western end of the Ningi Hills. But this observer is, unfortunately, 
not familiar with the Sabon Garri—Ningi country. His workin the 
Liuri-Kano area has been thorough and systematic, and I hope that 
before long he will publish his results, as this country is extremely 
interesting from a petrological standpoint. 
G. W. W. 
December 6, 1920. 
CARBONIFEROUS SPIRIFERINA. 
Sir,—In Dr. F. J. North’s recently published paper “ On 
Syringothyris Winchell and certain Carboniferous Brachiopoda 
referred to Spiriferina, D’Orbigny”’ (Quart.. Journ. Geol. Soc., 
vol. Ixxvi, pt. ii, November 30, 1920), there is a slight error with 
regard to the locality of the holotype of Spiriferina perplicata North 
(p.219). Thisshould be Treak Cliff, Castleton (asin “ Explanation of 
Plates ’’), and not Peak’s Hill. 1 take this opportunity to state that 
I have presented the holotype of this species (pl. xiii, figs. 7a—c), as 
well as the figured specimen of Spiriferina insculpta (Ph.) (pl. xu, 
fig. 11), to the Manchester Museum, where they will be more 
accessible than in private hands. It is unfortunate that the 
illustrations of Spiriferina perplicata do not do justice to the very 
distinct lamellose ornament and costation of this species. 
J. WiLrRip JACKSON. 
MANCHESTER MUSEUM. 
January 6, 1921. 
