/O LOWER PENINSULA. 



QUENSTEDTIA, N. Gen. 



Single cylindrical tubules, multiplying by lateral gemmation of 

 either single tubes, or many at once, surrounding the mother-tube 

 in a verticil, and remaining for a while in close contact with it, and 

 amongst themselves. After some distance the young tubes bend 

 outward with their ends, which separate and become free diverg- 

 ing branches, which, in their turn, again become mother-tubes by 

 renewed gemmation. The tubes are intersected by remote trans- 

 verse diaphragms. In places of contiguity they connect by lateral 

 pore channels, and in well-preserved specimens longitudinal rows 

 of spinulose crests project from the inner side of the tube walls. 



QUENSTEDTIA UMBELLIFERA. 



Synon,, Aulopora umbellifera, Billings. 

 AULOPORA CORXUTA, Billings. 



Tubules about two millimeters in diameter, delicately annulated 

 by wrinkles of growth. At variable intervals, single tubes, or from 

 six to twelve in a verticil, sprout from their sides and remain closely 

 attached to them and to one another for the length of about five 

 millimeters, when they bend outward and separate, radially diverg- 

 ing as free branches, which themselves soon throw out new verticils. 

 The central tube always grows straight on, at intervals, continuing 

 to gemmate. Loose stems with a verticil of branches at the end have 

 remote resemblance to a small Crinoid head on its stem. Within the 

 circle of branch tubes the central tube is generally dilated by a bulbi- 

 form inflation. The basal apices of the young tubes do not communi- 

 cate with the older tube by simply opening into it, but by a narrow 

 circular pore, narrower than the entire width of the channels. Besides 

 these connections with the basis, the young tubes connect by lateral 

 pore channels with the old tube, and laterally also among them- 

 selves. Diaphragms are quite distant, and not always observable ; the 

 longitudinal rows of spinules also are only noticed in very favorably 

 preserved specimens but are sometimes very well developed. By 



