Charoitcrs of .Iricnlif'cctcii. McCoy. — Cirfy. 293 
assumed in the later editions of Woodward's niantial, as, for 
instance, the fourth puhHshed in 1880 (p. 417). 
Many authors in discussing; the genus do not mention its 
typical species, hut several, chiefly those for whom Zittel's 
Handbook served as a basis, illustrate Avicidipecten by fig- 
ures of A. papyraccns Sowerby. \Miile in the German edition 
of 1885 Zittel figures ./. papyraccus in this manner he men- 
tions A. doccns and A. concavns as representative forms, with- 
out, however, designating them as the genotypes. With this 
exception Miller, in his North American Geolog}' and Pale- 
ontology, seems to be the only one who has used A. doccns 
as the type of Avicidipecten, and though the decision upon 
this point can not be made w^ith assurance, I believe that his 
course is the proper one, although possibly the species should 
bear a different name. 
As will be seen by a reference to ]\IcCoy's description, 
which I have quoted above, the recognition of the genus was 
due to observations made upon a fine suite of fossils from 
Lowick, Xorthumberland, one of which presumably formed 
the basis for th'e structural figure which accompanies the 
diagnosis-. Logically the species to which the Lowick spec- 
imens belonged, a key to which i; afforded by the illustration 
and locality, should be taken as llie type of the genus. It is 
unfortunate, however, that McCoy did not furnish an identi- 
fication of this form at the time Ai'iculipccten was proposed. 
It is evident that neither A. planiradiatus, described from 
the Carboniferous limestone of Derbyshire, nor A. ruthvcni, 
a single small specimen of which was found at Lowick, can 
be the form upon w^hich McCoy's observations were made. 
Four years later (in 1855), in British Paleozoic Rocks and 
Fossils, McCoy had occasion to treat the species of this genus 
at some length. The generic diagnosis and remarks (p. 392) 
are quoted verbatim from the original reference. The species 
of Aviculipcctcn are described in ;wo places, the Devonian ones 
with the other Devonian forms and the Carboniferous with 
the Carboniferous. Their arrangement is alphabetic. A. do- 
ccns, the sixth in sequence among the Carboniferous species, 
said to be common in the dark Carboniferous limestone of 
Lowick. Xorthumberland ; one of the figures is obviously a 
wash drawing of the same specimen of which a sketch accom- 
