BRACHIOPODA. 
229 
onstrated, though Noetling mentions {loc. cit., p. 368) having seen a specimen 
showing the internal characters, which convinced him that it could not be 
a true Pokambonites. The nature of these features, however, is not 
stated. Well preserved interiors of this shell must be of rare occurrence and 
opportunity is taken therefore of elucidating its structure by a series of trans¬ 
verse sections from the beaks forward. It will be seen from these accompany¬ 
ing figures that there is a spondylium in each valve, that of the pedicle-valve 
being at the outset the larger, and continuing further forward than the other. 
Both are supported by a stout median septal callosity, which, in the brachial 
Fig. 160. Fig. 161. 
Fig. 16-2. 
Fig. 163. 
Fig. 161. 
Fig. 165. 
Fig. 166. 
Figs. 160-166. Transverse serial sections of a single specimen of Spirifer (Noetlingia) Tscheffkini, showing the 
structure of the internal apophyses and septa. In all the sections the pedicle-valve (p) is above, 
the brachial valve (n) below. (c.) 
valve widens and becomes lost in the thickened shell-substance of the muscular 
region; that of the pedicle-valve becomes narrowed anteriorly and eventually 
leaves the spondylium free, or nearly so. These characters are not materially 
different from those of Pokambonites, but a feature of high significance in 
Spirifer Tscheffkini is the presence of a simple linear cardinal process in the 
spondylium of the brachial valve. This, with the long, double-areaed hinge¬ 
line, the biforate umbones and suggestive external reseinblance in contour to 
Platystrophia, forms a more strongly orthoid combination than has been here¬ 
tofore observed among shells with such pronounced pentameroid affinities, and 
thus makes a more direct connection between Pokambonites and the orthoid 
stock whence they have all been derived. The distinctive generic value of this 
shell as above expressed may be indicated by the term Noetlingia. 
