260 W. G. Fearnsides—Lower Ordovician Rocks of Scandinavia. 
A. The Dictyonema and Bryograptus Shales. 
Taking first the areas where sedimentation was completely continuous 
throughout the period A, we may begin with the Kristiania district. - 
Here the oldest beds in which we are interested are the upper beds of 
Professor Brogger’s 2d (K 1), which both paleeontologically and litho- 
logically belong to the Olenws or Alum Shale Series. hey contain 
Parabolina heres and Cyclognathus micropygus, and with them certain 
fragments of Asaphid trilobites, but as the Krekling section which 
I visited was only attainable by digging I can say little else about 
them. Above these come the 80 feet of shales 2e with Dictyonemu 
and Bryograptus, but without trilobites, and these seem to me capable 
of further subdivision. Unfortunately I have no detailed knowledge: 
of the difficult group of branching graptolites, but in the magnificent 
stream sections on the western side of the valley a lttle south of 
Krekling station one could easily recognize time mutations in the 
general aspect of the Diclyonema in the different beds. The earliest 
of them are usually ill preserved, and I could obtain no specimens. 
showing the proximal end. In adult stipes the cells are very 
indistinct, and rarely project more than about a quarter of the 
diameter of the common canal. The connecting-rods seem to take the 
place of cells, and though thin are very numerous. The stipes are: 
usually close together and very nearly parallel, they branch at all 
sorts of levels, and the resulting mesh has the form of somewhat 
elongated rectangles or parallelograms. Upwards this ancestral type 
of Dictyonema seems to diverge into two distinct families, the one 
approaching the true graptolites (Dictyograptus), while the other seems 
more nearly related to the Dendroids (Dictyonema, sensu stricto). Of 
these the former soon develops well-marked cells, which, though 
a trifle irregular, tend to become uniserial, and so come into agreement 
with the early graptolites, while in the latter a crinkly longitudinal 
ornament appears upon the polypary, and the cells though well 
formed are small and are developed spirally at angles of about, 
120°. With this divergence in the cell characters of the adult, we: 
are able to trace an even more notable change in the character of’ 
the proximal end, for whereas the Dictyograptus forms develop like a 
fisherman’s net from a sicula of no great length with primary branches. 
diverging at an angle rarely greater than 90°, the Dictyonemas. 
grow basket-like from a long narrow tube or nema, and diverge at 
angles which in the later forms approach 160°. The character of 
the crossbars also alters, for while in Dictyograptus their develop- 
ment is ever more and more delayed until they become practically 
abortive, in Dictyonema their importance increases, and the general 
aspect of the later forms is that of a square or rhomboid mesh 
in which crossbars and stipes are of approximately equal importance. 
Branching in both families appears to tend to dichotomy at regular: 
intervals, and hence the later Dictyonemas and Dictyograptids are 
very flabelliform. So far as one can judge the specimens figured by 
Brogger as Dictyograptus flabelliformis come a little more than half-way 
up the series at Krekling. They tend rather to the Dictyograptus 
than to the Dictyonema family, and as shown in the original figure 
exhibit well-marked cells on the outer stipes of the net. ‘The: 
