10 G. LINDSTRÖM, THE ASCOCERATIDA AND THE LITUITIDA. 
Journ. of the Geol. Soc. of London with the title »On the Silurian Rocks and their As- 
sociates in parts of Sweden». We there find the following Cephalopoda mentioned, viz: 
p. 20 Orthoceratites annulatus, ibex, ludensis, regularis, imbricatus, angulatus 
(O. virgatus Sil. Syst.). 
O. trochlearis His. is also mentioned, but as this is Lower Silurian it must have been 
found in an erratic block. 
E. Borr gave descriptions of several Gotland species in his »Beitrag zur Kenntniss 
der Silurischen Cephalopoden im norddeutschen Diluvium und den anstehenden Lagern 
Schwedens» in Mecklenburg. Archiv fir Naturgeschichte 1857. 
Page 16: Orthoceras columnare MARrkL., p. 18 O. Hisingeri (O. annulatum His.), 
p. 19 O. gottlandicum Borr, p. 20 O. verticillatum Vv. HAGENoW, Ö. ornatum Borr, p. 21 
O. cochleatum SCHLOTH., imbricatum WAHLENB., p. 22 O. Hagenowi Boll (= O. inter- 
medium MARKL., not BARRANDE), p. 24 O. angulatum WAHBLENB., p. 25 O. annulatum Sow. 
In 1859 Borr in »Petrefactologische Kleinigkeiten> (Mecklenb. Arch. p. 161) made 
some additions and declared that O. Hagenowi probably is identical with O. tenuis ErcHw. 
from Oesel. This can, however, not be the case, as EIcHWALD identifies his specimen with 
the Swedish Lower Silurian species of WAHLENBERG and moreover gives a very insufficient 
description. 
G. VoN HELMERSEN did not publish the relation of his tour in Gotland, undertaken 
in 1845, before 1858, as »Geologische Bemerkungen auf einer Reise in Schweden und Nor- 
wegen» (Mém. Acad. Sc. Imp. de St. Petersbourg T. VD. The only Cephalopoda which 
he enumerates are Orthoc. ibex (= O. annulatum), O. angulatum (by him identified with 
O. virgatum S. S.), fimbriatum Sow. (= 0. annulatum Sow.), thus only two species. 
Fr. SCHMIDT published in 1859 »Beitrag zur Geologie der Insel Gotland» (Archiv fär 
Naturk. Liv-, Ehst- und Kurlands 1:e Ser. Bd. II). He there enumerates O. cochleatum, 
annulatum S. S., undulatum 5. S.?, angulatum, cochleatum (from Slite, but this is quite 
another species, O. nummularium or other), gotlandicum Borr, Hagenowi Borr, imbrica- 
tum, Cyrtoceras leve S. S., Gomphoceras ellipticum M'Cor. 
J. BARRANDE gives in his grand work, Systeme Silurien de Bohéme in 1874, vol. 
II, part IIT, complete descriptions and beautiful figures of a number of Gotlandic species. 
We find there Orthoceras cochleatum SCHL. 
O. columnare MARKL. and BARRANDB himself identifies his own O. Dahlli 
with this species. 
0. gotlandicum, probably identical with HaAGESNow's O. verticillatum. 
O. Hisingeri Borr. 
0. imbricatum according to BARRANDE, but it is not certain whether also 
according to WAHLENBERG and certainly not identical with HISINGER'S 
species. I have given a new name to this species of BARRANDE and 
called it O. orientale (coming from the east of Gotland). 
