ANNELIDA— ERRANTI A. 247 



74. A. woodi Whitfield. Cambric. 

 Seldom as much as one eighth inch in diameter, generally less 



than one tenth, deflected at various angles near the surface of the 

 layer and often oblique for some distance, then horizontal along 

 the surface of the layer ; natural openings surrounded by hillocks ; 

 older borings compressed by new ones so as to appear crescentic 

 in section. 



St. Croix formation of Wisconsin. 



XVII. ScALARiTUBA Wcller. 

 Irregularly curving and twisting worm burrows, marked by 

 transverse ridges at a distance of 1-2 mm. Mississippic. 



75. S. missouriensis Weller. Mississippic. 

 Tubes 2-4 mm. in diameter, of subcylindrical form, never 



straight for more than a few centimeters. 



Crowded in Vermicular or Northview sandstone of the Kinder- 

 hook of Missouri. 



Of Doubtful Affinities. 

 XVIII. Arthrophycus Hall. 



Trails or burrows in relief (solidmoldof trail?), simple or appar- 

 ently branching, rounded or subangular, with median groove, and 

 close-set transverse grooves. Originally described as a plant, it 

 was subsequently regarded as worm burrows, but may be the 

 mold of a trail of some other (possibly terrestrial) animal. Siluric. 



76. A. alleghaniensis (Harlan). (A. harlani Conrad.) Siluric. 

 Internal mold of the compound burrow (or trail) composed of 



numerous, strong, rounded, elongate and articulated branches which 

 unite near the base; these branches are simple and approximately 

 of the same dimensions throughout; diameter of branches one 

 fourth of an inch to one inch. 



Medina and Oneida of Ontario and New York; Tuscarora of 

 Pennsylvania and Maryland; Clinch of Virginia, Tennessee, etc. 

 (On the under side of sandstone layers.) 



XIX. D^DALus Rouault. 

 (Including Vexillum Rouault.) 

 Vertical, flat, crimped or contorted plates often forming inverted 

 spiral, and composed of sandstone. Interpreted as representing 



