304 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the upper part is a gray marly limestone which in places is full of 
corals. Either division is readily distinguishable from the Wesen- 
berg (Schmidt states that the Lower Lyckholm resembles the Wesen- 
berg), for the latter is far more hard, more compact, and finer grained 
and partakes more of the aspect of a lithographic stone. I dissent 
from the general statement of Schmidt that few corals occur in the 
Lower Lyckholm. Locally they are not uncommon, but there are 
not nearly so many as in the Upper Lyckholm and the Borkholm. 
Bassler apparently was misled by the labels accompanying his 
specimens in considering that the Lower Lyckholm is characterized 
by Maclurea and Subulites and in respect to the gastropods, he 
appears to have reversed the sequence. Maclurea may occur in the 
Lower Lyckholm; but I have not seen it there, while it is common 
in the Upper Lyckholm. Subulites and large Hormotomas range 
throughout, but the latter are more abundant in the upper beds. In 
seeking for equivalents in American deposits, it is my Judgment that 
no correlative value can be placed on these large gastropods of general 
Middle Ordovician aspect. Bassler now agrees in this view, for since 
his correlation of the supposed Lower Lyckholm he has learned of 
numerous examples of the reappearance of faunas, and of the close 
resemblance of the North American Black River and early Trenton 
faunas to those of the Richmond. 
Although Bassler placed considerable emphasis on the Bryozoa 
in drawing his deductions relating to a time break, he appears to have 
relied more on the general aspect of the fauna. In respect to the 
Bryozoa it would be well to review those forms which he had in mind 
as indicative of Middle Ordovician time; these are Corynotrypa bar- 
bert, Diplotrypa petropolitana, Dittopora colliculata, Stellipora constel- 
lata, and Stomotopora arachnoidea. Each of these species is said to 
occur at Hohenholm, of which the present exposures are quite cer- 
tainly the Lower Lyckholm and such was probably true of the older 
ones as the topography does not lend itself to the view that strata 
much higher than those now shown were formerly exposed. Ditto- 
pora colliculata and Diplotrypa petropolitana also occur at Pallokiill 
and the latter at Paope; but as they occur at these latter localities 
with at least thirteen other species of the Lyckholm Bryozoa, consid- 
ered as evidence of “Silurian affinity,” it follows that they must 
almost wholly be neglected as evidence of age. Diplotrypa petro- 
politana, moreover, is so long ranging that it has hardly any strati- 
graphic value. Corynotrypa barberi and Stomotopora arachnoidea 
occur at Hohenholm growing on Richmondian and Silurian corals 
i 
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