BRACHIOPODA. 
25 
A subordinate division of this section is the 
(1) Hungerfordi-type, in which the fold and sinus are low, often obso¬ 
lescent, the outline suborbicular and the cardinal area compressed laterally 
and incurved; dental lamellae prominently developed. This type is repre¬ 
sented by 
S. prcBmonens, sp. nov., Niagara group. 
S. Hungerfordi, Hall, Lower upper Devonian. 
To the same division belongs the Russian species, Anossofi, de Verneuil, 
which Tschrrnyschew considers as probably identical with S. Hungerfordi and 
an important index fossil of his uppermost middle Devonian fauna on the west 
slope of the Urals. 
Here must also be placed the Spirifer Mosquensis, Fischer, from the Carbonif¬ 
erous limestone of Miaschkowa, Russia, and the type of the genus Choristites, 
Fischer. Spirifer Grimesi, Hall, of the Burlington limestone resembles this 
Russian species in external form, but lacks the prominent development of the 
dental lamellae and the simple lateral plications possessed by S. Hungerfordi 
and S. Mosquensis. In our opinion, if the term Choristites is to be admitted 
with subgeneric significance, it should be restricted to this small group of 
species beginning in the upper Silurian and ending in the Carboniferous. 
(b) Striatus-type. Forms having a great number of duplicate lateral plica¬ 
tions, well developed, rarely acuminate fold and sinus, and narrow, usually 
extended cardinal area. Species following closely the type of S. striatus are 
not common in American faunas though they abound elsewhere. We have: 
)S. striatiformis, Meek, Waverly sandstone. 
S. Logani, Hall, Keokuk group. 
S. striatus, Martin, Coal measures. 
S. Marcoui, Waagen, Coal measures. 
An important subsection of this group is composed of a series of forms 
representing successive stages in a line of development, which diverged early 
from the Striatus-stock and eventuated in some extravagant expressions of 
this type. 
* Die Fauna des mittleren und oberen Devon am West-Abhang-e des Urals, pp. 174, 175. 
