310 R. R. GURLEY 
“The Graptolitidee are therefore at this time clearly traced to the base of the 
Carboniferous system, and we may probably find allied genera to the close of the 
Paleeozoic period.” 
In a collection presented to the U.S, National Museum, by Mr. R. A. Blair, of 
Sedalia, Mo., a Dictyonema was pointed out to me by Mr. Charles Schuchert, Curator 
of Paleontology. I have elsewhere described it as D. d/azrz. Associated with it are 
some poorly preserved specimens which bear, as Portlock would say, “a strong 
resemblance to some of the double Graptolites.” I am, however, inclined to think it 
only a superficial resemblance, and pending further collections can assert the existence 
of no graptolite fauna other than D. d/azrz. Concerning that species there is no room 
for doubt. 
COMPOUND AND SIMPLE FORMS IN THE DIPLOGRAPSIDA, 
The recent paper of Ruedemann*™ unquestionably marks a real advance 
in our knowledge of Dzplografszs structure. Although I have not seen the 
specimens, I am prepared to accept the results described, as several years ago 
I saw a similar specimen on which a good many individuals of Diplograpsts 
foliaceus Murch., were so grouped as, on the doctrine of probabilities, to 
render it almost certain that they must have grown radiatingly from a 
common center. The specimen did not, however, show the common center. 
Since then I have seen a similar specimen in Professor Hall’s collection 
which is still less equivocal. With better material Ruedemann has given a 
very interesting description of the structure, and has I think proved at least 
the following: That in two Diflograpszs species the stems (‘‘ polyparies,” as we 
have been calling them) formerly regarded as simple and complete in them- 
selves, are in reality only fragments of compound aggregates, relative to 
whose center the so-called “distally prolonged virgula”’ is in reality proximal, 
and the position of the sicula distal. 
Such a discovery is to a certain extent revolutionary of our views of 
diplograptid structure, and is in importance comparable only to Hall’s similar 
discovery of central connections for many of the numerous fragments 
previously lumped together as Monoprions and Monograpti on the easy 
“‘cells-on-one-side”’ character. 
But (and this is the principal vazson d'etre of this section) it seems to the 
writer that induction from these two Dzplograpsis species to the Dziplograp- 
side in general may be premature. And it is to the generalizations that 
Ruedemann has made (and very properly, indeed, from the standpoint of 
his material alone) that attention is directed. 
The real question seems to be the magnitude of the taxonomic value of 
the discovery. In two Climacograptus species (C. caelatus, C. phyllophorus) 
t Amer. Jour. Sci., 1895, pp. 453-455, Figs. 1-5. 
