146 PERMIAN FOSSILS. 
Genus Apithyris, Phillips,’ 1844. 
TEREBRATULA, Auct. 
18® Sous-Srct., 1** Div. Bracutop. (? partim), Hudes-Deslongchamps, 1837. 
Diagnosis —A longitudinally-oblong Terebratulidia; furnished with prominent 
dental plates, and a transversely semi-elliptical, moderately recurved Joop. 
Type Zerebratulites elongatus, Schlothem. 
Professor Phillips, in his ‘ Paleeozoic Fossils,’ proposed the name Lpithyris as a 
substitute for that of Zerebratula ; and at the same time applied it to a generic group, 
which he characterised as having ‘“‘the beak truncate, perforate.” The name has 
hitherto been considered in the light of a synonym; but I propose applying it to one 
of the subdivisions of the old genus Verebratula, represented by the Permian species 
above named, and distinguished from all its co-ordinates, hitherto noticed, by having 
its rostral cavity furnished with promment dental plates, and its apophysary system 
somewhat resembling the half of a transversely bisected ellipsis. Waldheimia is 
most intimately related to Lpithyris; but the difference will be at once evident by a 
reference to the figures representing their respective internal structures (vide Pl. VI, 
fig. 45; Pl. XX, fig. 11). In Waldheimia the loop is elliptical, deeply recurved, 
and projecting about two thirds of the length of the shell; but in Lpzthyris it is semi- 
elliptical, moderately recurved, and projecting about one third of the length of the shell. 
The differences just noticed clearly indicate a distinction im the animal; because, 
from the short and slightly recurved character of the loop of Apithyris, it must be 
concluded that the labial appendages have been either unusually short and attached 
throughout their entire length, or long and free towards their base. But in either case 
a difference is involved, of sufficient importance to constitute a generic distinction 
between Hpithyris and Waldheimia ; masmuch as im the latter the labial appendages, 
although long, are nevertheless attached throughout their entire length. In the view 
taken, Hpithyris also becomes related to Zerebratula; but the greater distance of the 
cross piece of the loop from its crura, in the former, indicates that the visceral mass 
has been more voluminous than it is in the latter. The difference in this respect is 
still greater between Hpithyris and Waldheimia, in consequence of the cross piece of 
the latter being brought nearly in contact with the crura (vide Pl. XX, fig. 11). On 
the whole, it would appear that the present genus, in its loop and labial appendages! 
is intermediate between Terebratula and Waldheimia. 
Tnthyris appears to have been the earliest created genus of eect. as 
species occur in the Devonian rocks: remains are also present in deposits belonging 
to later periods ; but none are known to me as occurring in more recent rocks than the 
Jurassic. 
 Paleeozoic Fossils, p. 55. 
