112 THE PALEONTOLOGY OE MINNESOTA. 



IVluella 



Class BRYOZOA, Ehrenberg. 



Order GYMNOL^MATA, Allmann. 



Sub-order CTENOSTOMATA, Busk. 



Family ASCODICTYONID^, Ulrich. 



Genus VINELLA, Ulrich. 



Vinella, ULKicn, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 173. 



Zoarium attached to foreign bodies (shells, etc.), consisting of exceedingly 

 slender, ramifying, thread-like, tubular stolons, arranged more or less distinctly in 

 a radial manner. Surface of tubes sometimes faintly lined longitudinally. A row 

 of widely separated small pores along the center of the surface of the tubes. Zooecia 

 unknown. 



Type : Vinella repens Ulrich. 



The fossils for whose reception this genus was proposed are regarded as related 

 to Vesicularia, Thompson, and probably also to Mimosella, Hincks, both of them 

 genera of recent Bryozoa. The zooecia must have been deciduous and developed by 

 budding from the creeping stolons at the points now represented by the small pores. 

 The form that is designated the type of the genus, though one of the rare fossils of 

 the Trenton shales of Minnesota, is justly entitled to that distinction, because it is, 

 so far as our knowledge at present extends, the earliest existence of the genus. 

 Similar organisms are known to occur more or less rarely in the Hudson River, 

 Niagara, ? Hamilton and Chester groups of rocks in America, while in the Wenlock 

 of England and Gotland, the Ascodictyon radiciformis Vine, is unquestionably a con- 

 generic form. Still another form that I would refer to this sub-order is repre- 

 sented in my collection by several zoaria from the Upper Coal Measures at Spring- 

 field, Illinois. 



In the absence of the zooecia a satisfactory classification of these mostly obscure 

 organisms is perhaps impossible. Our observations are limited to the creeping sto- 

 lons which, even in the recent Ctenostomata, a.Ye but illy diagnostic of generic types. 

 Better material, carefully studied, may later on demonstrate the advisability of 

 erecting other genera for some of the types now classed as Ascodictyon and Vinella. 

 In the present state of our knowledge it is also most difficult to decide the exact 

 limits of the genus Ascodictyon, Nicholson and Ethridge, jun., and the only plan that 

 now appears feasible is to include all, and only such forms as possess the ovate or 



