114 THE PALEONTOLOGY OF MINNESOTA 
(Rhopalonaria, Vinella. 
other eighteen. In the absence of good examples of the English Wenlock species, 
Vinella radiciformis Vine, sp., which these specimens must greatly resemble, I propose 
to designate the American form provisionally as var. conFERTA, in allusion to the 
unusually close development of the nuclei. 
The inclusion of all the paleozoic Ctenostomata in one family, the Ascodictyonide, 
(see Geol. Sur. IIl., vol. viii, p. 335) is likewise only a provisional arrangement. 
Indeed, I am satisfied that Rhopalonaria, Ulrich, at least, which is evidently related 
to the recent Arachnidiwm, Hincks, belongs to a distinct family. 
Figure Se is taken from the best example of Rhopalonaria venosa Ulrich, now at 
hand.* This species, so far as known, is restricted to the upper beds of the Hudson 
River group, and the specimen now illustrated is from those beds at Waynesville, 
Ohio. Usually nothing remains to attest the former presence of this bryozoan, 
except a series of shallow excavations in the substance of the body upon which it 
grew. These excavations, however, correspond very well with the form, or rather, 
the outline of the cells and extremely delicate connecting stolons of the zoarium it- 
self. The latter must have been quite liable to destruction during the process 
of fossilization, and, though diligently searched for, not a single example, so far as I 
am aware, has yet been found in which it is preserved in even a fairly satisfactory 
manner. In the best specimens the stolons are clear enough, but the swollen por- 
tion of the zocecia is always more or less obscure. Now and then, it is true, some 
evidence is presented to show that the orifice was situated near one end in the center 
of a slightly elevated portion of the surface. These facts, though unfortunate, tend 
nevertheless to establish the ctenostomatous affinities of the fossil. If, as already 
intimated, Rhopalonaria is related to Arachnidium, then perfect zoarial preservation 
is not to be expected. On the contrary, if such a condition were common, as in cal- 
careous zoaria, the relationship might well be doubted, since the almost membran- 
aceous zoarium of Arachnidium and many other Ctenostomata, is, perhaps, quite 
incapable of preservation in a fossilized state. 
VINELLA REPENS Ulrich. 
PLATE I, FIGS. 1-5. 
Vinella repens ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 174. 
Original description —*Zoarium repent, the stolons delicate, thread-like, often 
longitudinally striate, straight or flexuous; from 0.06 to 0.11 mm. in diameter; 
bifurcating often and sometimes arranged in a radial manner about a central node. 
Where best preserved, very small pores arranged uniserially along the center of the 
*The original type of the genus and species has been mislaid or lost. 
