Soe

Protrachyceras Longobardicum Mojsisovics, have been described. The same
features aovear in the holotype and similar specimens of Protrachyceras
sikanionum. Comoysred with P. longobardicum, the Canadian species has fewer

rows of tubercles and a simoler suture line, and the lateral bullae avopear

at an earlier stage of zrowth.

Protrachyceras zauwae MclLearn
(Plate I, fieure 1)

Originally described asa variety of Protrachyceras sikanianum this is
noW recognized as a species.

Reference has aileeade been made to the manner in which sorade tubercles
apoeared in the late Ladinian species Protrachyceras archelaus Laube and
the early Karnian svecies P. septemspinatum Mojsisovics. The same ornament
apoears in the Canadian svecies Protrachyesras zaumae, which is smaller than
P. archelaus, and in which the goinate tubercles apoear at a later staze of
erowth and are probably coarser. Compared with Protrachyceras septemspinatum
Has) FM are cer ther apart at maturity, and the rows of tubercles are one
less tn number . events Ve BRObADIY closer to BR. archelaus than to

| Pe eptemspinatum. |

earn RO a ; Genus Paratrachyceras Arthaber

| When Bete eine the Sane Paratrathyceras, Arthaber gave a long list of
species teins Tnevued nigay) Ahir “Al thouch they all show reduction in tubercles,
GIR Aakers far removed Proubthe enotype of Paratrachyceras, P, hofmanni
Boeckh, 9 be included in thig @enus- ees already been noted under
Protrachyceras , and no doubt they will receive attention whenever the genus
Protrachyceras is revised,

| The following species Boeniclese énough to the zenotype to be included
Ae panel racre Gran: the late Ladinian species Paratrachyceras richthofeni

Mojsisovics, P. regoledanum Mojsisovics; P. mundevillae Mojsisovics, and
| P. lec reeie Diener and the early Karnian species P. hofmanni- Boeckh, the
fenotyve, and i) dichotoman Muenster. The early Karnian typical species are
much rior aneeiate than the late Lad inian species, which are fairly eeointe.
The Bae line of the early Karnian species is ammonitic and subammonitic,

that of the late Ladinian species ig not known. All have numerous, fine ribs

finer on the average in the carly Karnian than in the late Ladinian, fairly

CERES ER LEIA. TUSTIN eI TR ed PAD NAT ASA CP RN OAT Oe UN HLCP a DE a Ne