DAVIDSON — ON BRITISH CARBONIFEROUS BRACHIOPODA. 
53 
modifications lead us gradually to Sjj. rliomhoidalis, wliicli might also 
be nothing more than a variety of Sp. glabra. I merely express here 
on this and other questions the results of my own impressions or 
personal observations, which may be more or less erroneous. Sj). TJrii 
is a good little species, which I beUeve to be a recurrent form of the 
Devonian, and present also in the Permian strata, notwithstanding 
Prof. King's assertion to the contrary. 
Sp. Carhikiensis, as far as I know, is also distinct ; while Sp. lineata 
is another excellent species, but exceedingly variable in shape and 
sculpture ; at one time I felt disposed to unite with it Sp. elllptica; but 
having subsequently felt somewhat uncertain, have since preferred to 
consider it provisionally separate. 
Sp. Uni, Sp. lineata, and I believe Sp). ellipAica had their surfaces 
closely covered w^ith numerous small spines, and it is possible that 
other forms were so invested. 
Spiriferina. — Of this subgenus three species only appear to have 
been properly distinguished, viz., Sp. laminosa, Sj^. insculpla, and Sp. 
cristata, var. odoplicata. Sj). minima has been established on one or tw^o 
specimens still very doubtfully characterized ; as all my efforts have 
been unsuccessful in the endeavour to obtain more, I consider the 
name hardly worth retaining. 
Cyrtina. — Of this subgenus two good species appear to exist, viz., 
G. septosa and G. carbonaria, a third, G. dorsata, is somewhat doubt- 
fully determined, on account of the imperfect material at my command, 
which consisted of two fragments only from the Carboniferous 
limestone of Cork, in Ireland. It would, therefore, be very desirable 
that geologists in that locality should have a search for better speci- 
mens. 
Bhyrichonella. — Nine species are provisionally retained ; but the 
claims oi Bh. cordiformis have not been satisfactorily established ; and 
of Rhynchonella ? gregaria but two imperfect valves have come under 
my examination. Bhyjichonella ? trilatera appears to be also a very 
rare species, for I am acquainted with only a very few specimens 
from Derbyshire, in the British Museum, and in that of the School 
of Mines : it appears also to be a rare shell in Belgium. Rli.? nana 
and Rh. semisidcata are by far too doubtful to deserve more than a 
passing notice ; and it is deeply to be regretted that palaeontologists 
can bring themselves to fabricate species on such insufficient and 
imperfect material, adding only confusion where such should be care- 
fully avoided. 
Gamarophoria. — Four species have been recorded ; but more 
abundant and better material with reference to G. isorlujncha and 
G. lateralis must be obtained before these can be definitely adopted. 
Of the first I am acquainted with but a single imperfect example : 
of the second, with those only in the Cambridge Museum. 
G. Grumena, Martin, is a weU made out species, and evidently the 
same as that from the Permian rocks knomi under the designation of 
G. Schlotheimi ; and although I consider myself justified in referring 
Terebratula rhomboidea and T. seminula of Phillips to the same 
