NS a ae eee I Oe aE ES Re TT 
E. Billings on the Genus Athyris. 49 
jected to by several sire gens hen yet t bal and in conse- 
) 0 thereof, abandoned by its author, yet I believe that on a 
reful examination of all the circumstances, it will be found to 
le perfectly just toward the parties concerned, and in no respect 
inconsistent with the rules of zoological nomenclature. It was 
the first subdivision of the — published, and should therefore 
e precedence over all othe 
Pespenily to 1853, Athyris was only known as a single —— 
genus of brachiopoda which included such forms as atula 
concentrica von Buch, 7: tumida Dalman, and 7. Herculea Bar- 
rande. In that year Mr. Davidson divided it into two smaller 
genera, confining the name Athyris to that section for which it was 
most appropriate, with twmida or Herculea for the types; and 
adopting Spirigera D’Orbigny for the other type, TJ. concentrica, 
r was re ope _ Athyris, as then re-defined, included 
wo gener uence it has been again divided by 
arating ‘all grab vain by 7. Herculea under the name = 
Merista , a genus proposed, but not clearly characterized by Pr 
ctor in 1851. This i is me: classification which I believe to eS 
the true one. While di it I shall, throughout this paper, 
when I may have EME e efer to gu species above-named, 
designate them, Athyris tumida, Spirigera concentrica, and Me evista 
Herculea. 
Those who are opposed to this arrangement contend, that as 
all the species which McCoy placed in the eye at the time he 
first described it, belong to the group typified by S. concenirica, 
the name Aéhyris must be retained for that group, and cannot 
sed be transferred to the other ee of which A. tumida is the 
is reasoning, according to my views, can only hold 
pi in case it be first proved that McCoy specially confined the 
genus to species having the generic characters of those in his 
engine) list, or pointed ons 6 one of them as the type, or drew up 
diagnosis in such a ner as to exclude A. tumida. In 
er I shall ete SC 3 to show 
t McCoy did not limit ie genus to the species first 
aa in it. 
2. That on the contrary he and other wortpees understood. 
it . include both A. tumida and 5S. cone 
3. Tha 
subdivision ae Bo Davidson in 1853 cannot be setae 
and shall quote some of the laws above eer in inn 
uch of this, of course, belongs to the common ’ knowl- 
edge of all paleontologists conversant with the fossils of the olde: 
Am. Jour. Sci.—Szconp Sexes, Vou. XLIV, No. 130.—Juty, 1867. 
7 
