24 Calvin on a new Tubicclar Annelid. 
abounds in gravel which apparently represents the quartz. 
This bed probably continues southward until the Kewatin lie- 
comes the subjacent formation; and the latter, accordino- to 
uniform obserxation, must stand in ^•ertical conformity with the 
gneiss. 
It is noticeable here that the lowest beds of che bluff are 
v\ anting in the pit. The higher beds appear to extend farther 
northward, as if the gneiss had been subsiding during the deposit 
of the ^Vnimike. The iron, too, is located in these beds, though 
generally the iron horizon is considered to belong in the lower 
part of the formation. 
Similar unconformities of the Animike as described, on the 
iron-bearing series as described, are repeated, apparently, in the 
Marquette region. But in this place I must restrict my remarks 
to Minnesota. 
If the magnetitic, Iluronian Animike reposes unconformably 
on the hiematitic, uncrystalline, super-Laiu'entian series of the 
lake .Superior basin, we haye a wide-extended system of slates 
Axhich in\ itcs serious taxonomic consideration. 
ON A NEW GENUS AND NEW SPECIES OF TUBICOLAR 
ANNELIDA. 
ISV PROFESSOR S. CAL\IX. 
I ani indebted to professor B. Shimek of the Iowa City High 
School for a number of fragments of Acerv7ilaria davidsoni 
Ed. and H., which contain as enclosures the shells of a yery 
peculiar and yery interesting tubicolar worm. The s)3ecimens 
were procured at Robert's Ferr}' in Johnson countx, Iowa. So 
far as I now know the tubes of this worm are only found em- 
bedded xertically in the solid coralla oi Acervularia. Further- 
more the species, except at the locality mentioned, must be ex- 
ceedingly rare. Of the many hundreds of specimens of Acer= 
vularia that I ha\e collected, or seen exposed at the cpiarries or 
along the natural exposures near Iowa City, at Littleton, or at 
numerous other places where this coral abounds, none haye 
shown any indications of the tubes in question. If the tubes 
