BRACHIOPODA. 
91 
crura not only at their apices but for a short dis¬ 
tance along their inner faces, not making the 
nooses peculiar to Athyris proper; they are broad 
and blade-like, narrowing beyond the insertion of 
the loop; the loop is situated posteriorly ; the 
accessory lamellae are narrow near their origin, 
broaden and then taper again, having the shape of 
a sickle. The spiral ribbon, from the figures given 
by Davidson and King, appears to be pectinated on 
all its outer edges, but it has not been shown that 
the anterior extremity of the loop is similarly 
ornamented. 
Fig. 64. 
The Umbriated spirals ot Athyris pectin- 
ifera, Sowerby. (Davidson.) 
These features are of sufficient significance to distinguish this group of 
species from the typical division of the genus. It must be granted, that as the 
really essential differences are in the structure of the spirals and loop, it 
will be impossible to make a final arrangement of these species until their 
internal structure has been fully elucidated. Temporarily, however, the char¬ 
acter of the external ornament may be relied upon, inasmuch as we know 
the internal arrangements with which it is associated in the type-species, 
Cliothyris pectinifera. 
This subgenus is equivalent to Waagen’s section Ornate, typified by the 
Athyris Roysii, Leveille,* under which he includes, besides A. Roysii and A. 
pectinifera, five new species (A. suhexpansa, A. capillata, A. semiconcava, A. acuto- 
marginalis, A. glohulina), all from the upper and lower divisions of the Productus 
limestone of the Salt-Range of India. In American faunas Cliothyris is rep¬ 
resented by the species usually identified as A. Roysii, in the Waverly and 
Keokuk divisions of the lower Carboniferous, A. hirsuta, Hall (= A. americana. 
Swallow), from the St. Louis and Chester limestones, and A. sublamellosa. Hall, 
from the Burlington limestone. 
* Productus limestone Fossils, p. 473. 1883. 
