86 LOWER PENINSULA. 



specimen with closely clustered tubes, found in the Hamilton group 

 of Alpena. 



CANNAPORA, Hall. 



{Compare Fletciieria, Milne-Edivards.) 



Colonies of closely approximated, erect tubules with stout walls, 

 sprouting from an incrusting basal expansion formed of prostrate 

 tubules growing and multiplying in the same manner as an Au- 

 lopora. The erect ends of the tubules are annulated by Avrinkles 

 of growth and by sharp-edged, periodical offsets marking an inter- 

 ruption and renewed growth from the inner circumference of the 

 old orifices. The sides of the tubes are partly connected by hori- 

 zontal expansions of the walls, partly in direct contiguity, in which 

 latter case the otherwise circular tubes are pressed into a polygonal 

 shape, and connect in the contiguous parts by lateral pores. The 

 orifices are slightly dilated at the margins, radiated by twelve 

 spinulose projections, rows of which extend through the whole 

 length of the tubes. Diaphragms are not often developed, direct 

 transverse, and not funnel-shaped as in Syringopora. Consider- 

 able afifinity exists between Cannapora and Aulopora. 



CANNAPORA JUNCIFORMIS, Hall. 



Tubules from one to one and a half millimeter in diameter, 

 forming large colonies of convex growth, with regular, subparallel 

 stems in the larger masses ; but in smaller specimens, representing 

 incrusting basal portions, the tubes are sometimes agglomerated in 

 irregular manner. Structure in conformity with the above given 

 general generic description. Found in the Niagara group of Drum- 

 mond's Island, and sometimes in the drift. In New York State it 

 is found in somewhat lower position in calcareous layers of the 

 Clinton group. The tubes of the New York specimens are some- 

 what smaller than those of the specimens from Drummond's Island. 



Plate XXXIII., Fig. 4. — Lower specimen on left-hand side is 

 a silicified young colony from Drummond's Island ; the lower figure 

 on the right-hand side is a fragment of a specimen from the Chnton 

 group of Brockport, N. Y. 



