OKTHOCERATIDJB. 
109 
four or five in the interspaces, and about the same number on the 
sides and summits of the annulations. 
KemarJcs. I have united these two species of Pleming because I 
cannot find any sufficiently distinctive character by which to 
separate them. The only feature relied upon by Fleming to dis- 
tinguish 0. undatum from 0. indcatum was the alleged smoothness 
of the shell in the former : but this, as pointed out by M‘Coy (Joe. 
cit.), may be accounted for by the absence of the shell, the striations 
being too feeble to leave any marks upon the cast. It is true that 
the specimen figured by Phillips in the ‘ Geology of Yorkshire ’ (loc. 
cit.) differs slightly from the Scotch specimens in the Collection in 
the character of the ribbing, which is more prominent and acute, 
but the specimen is only a small fragment, and the feature observed 
may be an individual peculiarity. M‘Coy remarks that 0. sulcatum 
tapers more slowly than 0. undatum ; this may be so, but the 
specimens before me are too fragmentary to show such a feature 
satisfactorilv- 
From 0. dactifliophorum, de Kon., the present species differs in 
its more rapid rate of increase, and in the entire absence of longi- 
tudinal lines upon the surface of the shell, which are present in the 
former. 
Horizon. Carboniferous Limestone. 
Locality. Bowes, Yorkshire. 
Ptepresented by the specimen figured by Phillips (Geol. of Yorks.) 
and contained in the “ Gilbertson Collection *’ in this Museum. 
Orthoceras angulare, Phillips. 
1830. Orthoceras anyulare, Phillips, Geol. of Yorkshire, pt. ii. p. 238, 
pi. xxi. f. 4. 
Bp. Char. A very imperfect fragment (the type specimen) is 
described by Phillips under this name ; “ subcylindrical with a few 
longitudinal furrows ; septa very distant.” The septa are slightly 
oblique, and are four lines distant in a diameter of eight lines. 
JRemarlcs. A faintly marked ridge is present upon what appears 
to be the inner shell-layer, and a shallow furrow is observable 
upon the cast, whence the shell has been removed, and it might be 
inferred from this that the shell was ridged longitudinally, but the 
specimen is too imperfect to justify a confident assertion on this 
point. 
Horizon. Carboniferous Limestone. 
Locality. Bolland, Yorkshire. 
Represented by Phillips’s type in the “ Gilbertson Collection.” 
