224 
AUG. F. FOERSTE 
longitudinal ridges. The first of these definitions evidently is 
based on the species cited in McCoy’s text. The second definition 
is based on the original description of the genus and the small ac- 
companying figure. Accepting the latter as the more correct in- 
terpretation of the genus, the forms possessing only transverse 
striae and no longitudinal markings, have no distinct generic 
designation, and the term Perigrammoceras here is proposed. 
Bassler lists under Cycloceras a number of species having ver- 
tical striae or ribs in addition to annulations. These include Or- 
thocey^as crocus Billings, 0. ohms Hall, 0. olorus haffinense 
Schuchert, 0. perroti Clarke, and 0. teretiforme Hall. It is not 
knov^n definitely whether Orthoceras leseuri Clarke, O. nicoUeti 
Clarke, and 0. rectiannulatum Hall belong to the same group as 
the preceding list, since the finer surface structure of these 
species is not known, only the presence of annulations being cer- 
tain. It is probable that these Ordovicion forms are distinct gen- 
erically from typical Cycloceras, as found in Carboniferous 
strata. Provisionally they are associated with Spyroceras. 
Orthoceras inceptum Foerste and its variety acceleratum 
Foerste apparently belong to Orthoceras, as far as known. 
Orthoceras (Cycloceras) novacarlislense Foerste has sharply 
defined transverse striae, but no annulations. Evidently it does 
not belong to Cycloceras. Its nearest relationship probably is 
with Geisonoceras. 
The transverse striae of Orthoceras amycus Hall, are gently 
frilled, and the species belong to Dawsonoceras. 
22. PERIGRAMMOCERAS GEN. NOV. 
PLATE XXVII, FIGS. 3 A, B. 
Genotype: Orthoceras laevigatum, as figured by Foord, in Carb. Ceph. 
Ireland, 1897, pi. 5, figs. Id, le 
Orthoceracones with transverse annulations and striae, but 
without vertical striae or ribs. Carboniferous. 
It is not known definitely whether this genus is represented in 
earlier strata or not. In annulated forms with transverse striae 
occurring in the Ordovician and Silurian it usually is possible to 
detect also vertical striae or ribs, if the surface is sufficiently well 
preserved. 
