8o LOWER PENINSULA. 



SYRINGOPORA VERTICILLATA, Goldfuss. 



Large aggregations of parallel or diverging tubular stems, from 

 two to three millimeters in diameter, keeping a distance of from two 

 to five millimeters apart, across which they connect at various not 

 very close intervals by narrow, transverse, branch tubules, of which 

 two or three are always sent off at nearly the same height, but 

 not in true verticillate position. The tubes are filled by invaginated, 

 irregularly funnel-shaped diaphragms, attenuated at the lower ends 

 into long siphons. The longitudinal rows of spinules are rarely 

 well preserved in the tubes of the specimens which are all found in 

 silicified condition. The colonies of stems are often large, several 

 feet in diameter ; their basal portions, composed of prostrate, irregu- 

 larly reticulated expansions of stems, differ considerably from the 

 erect parts, and among the specimens of colonies a great many 

 variations occur as regards the size of the tubes or their mode of 

 growth. In some the stems are distant, in others near ; in some 

 perfectly straight, in others flexuose or geniculated, with regular, 

 verticillate side connections, or with dispersed side arms branching 

 off at remote intervals or in closer proximity. These associated 

 forms, sufficiently contrasting in the extreme, I have not attempted 

 to divide into several species, but consider as variations of Syringo- 

 pora verticillata, whose enumerated specific characters can not of 

 course retain the limited form, applying only to a single variety 

 which accidentally fell into the hands of Goldfuss, the first de- 

 ■scriber of this species. Found abundantly in the Niagara limestone 

 -of Drummond's Island, Point Detour, and in nearly all other fossil- 

 iferous outcrops of the formation in the western part of the Upper 

 Peninsula. 



Plate XXX. — Fig. i represents a silicified specimen from Drum- 

 mond's Island, closely similar to the specimen figured by Goldfuss. 

 Fig. 2 has somewhat smaller tubes, with less regularly disposed, 

 transverse branch channels and more flexuose stems than the other. 

 With the above-described specimens others are found, which seem 

 ;to agree with Syringopora cancellata of Milne-Edwards. They are 

 vcoraposed of fiexuose tubes about one and a half millimeter wide, 



