LOWER CAMBRIAN. 4] 
the contained ccenosare continues to elongate itself until it ruptures the 
delicate pellicle of chitine which closes the extremity of the ramulus. It 
then extends itself, quite naked, into the surrounding water, and a constric- 
tion takes place at some distance below its distal extremity in the parts 
still covered by the chitinous perisare. The constriction rapidly deepens 
and ultimately cuts off a piece, which slips entirely out of the perisarcal 
tube and becomes a free zooid, while the surface of disseveration soon heals 
over and the axial cavity of the free frustule becomes as completely closed 
as at the opposite end. 
In tracing the further history of the frustule, it was found that this 
never directly develops a mouth or becomes transformed into a hydranth. 
After a time a bud springs from its side, and it is from this bud alone that 
the first hydranth of the new colony is developed. 
I have mentioned this type of fission on account of the rarity of repro- 
duction by that process among the Hydroida. It departs quite widely from 
the mode of fission described by Dr. Lang, and is not, I think, comparable 
with that which takes place in Laotira cambria. 
FOSSIL MEDUS® OF THE LOWER CAMBRIAN TERRANE OF EASTERN 
NEW YORK. 
The manner of occurrence and the mode of preservation of the one 
species found at this horizon in America are stated in the discussion of the 
relations of the Middle Cambrian fossil medusz to those of the Lower 
Cambrian (p. 8) and in the following description of the species: 
Genus DACTYLOIDITES Hall. 
DACTYLOIDITES ASTEROIDES Fitch. 
Pls. XXIV to XXVIII. 
Buthotrephis ? asteroides Fitch, 1850. Trans. New York State Agric. Soc., Vol. IX, 
for 1849, p. 863. 
Dactyloidites bulbosus Hall, 1886, Thirty-ninth Ann. Rept. Trustees State Mus. Nat. 
Hist. New York, for 1885, p. 160; pl. 11, figs. 1, 2. 
Dactyloidites asteroides Walcott, 1891. Tenth Ann. Rept. U. 8. Geol. Survey, Part I, 
p- 605; fig. 61, p. 606; Pl. LVII; Pl. LVIII, figs. 1, 1a. 
The description and figure of this species by Dr. Asa Fitch are very 
incomplete, but they are sufficient for the identification of the species in 
1 Loe. cit., pp. 152, 153. 
