STAUEASTEUM. 151 



Yar. HEXACEEUM, Wolle. Plate LXII, fig. 3. 



Somewhat stouter than the typical form and furnished 

 with six arms. 



Ponds, northern counties of New Jersey. 



In the possession of six arms it bears some resemblance to 

 St. coronulatum, but with nearly twice the length, and in the 

 absence of the circle of large granules on the convex end, 

 which suggested the name, it appears more nearly related to 

 St. ankyroides. 



St. NANtJM, Wolle. Plate LV, figs. 8, 9, 10. 



Very small, smooth, or granulate-punctate; semi-cells sub- 

 cuneate, sides somewhat rounded, ends broadly convex ; 

 superior angles produced laterally into straight slightly di- 

 verging arms, nearly as long as the diameter of the cell, ends 

 forked ; viewed from the end tri-radiate, sometimes twisted 

 so that the arms of the lower half cell alternate with those 

 of the upper half. 

 Diameter 20-25 jM. 



Frequent in ponds, Mt. Everett, Mass. 



This minute species is nearest St. graoile, Ralfs, but differs 

 in its smaller size, more forked apices, and smoother mem- 

 brane. 



St. vestitum, Ralfs. Plate LVI, figs. 28, 29, 30. 



Cells rough with minute granules ; with this investment 

 there are also minute emarginate spines ; semi-cells fusiform 

 in front view ; seen from the vertex, triradiate, each side 

 having two slender, forked spines in the middle, and often 

 accompanied by other smaller ones. 

 Diameter 62-90 jj. 



Has a home in many parts of the civilized world, so here 

 also it is found widely scattered. 



St. Sebaldi, (SanctiSebaldi), Eeinsch. Plate LVII, figs. 1-6; 10. 

 One-fourth to one-half wider than long, coarsely granulate; 

 margins in part granulate-crenate, and in part spinous. 

 Semi-cells broad cuneate, base truncate, toj) convex, with 

 sides more oi' less conically produced ; apices bifid or trifid ; 

 near the top margin a series of emarginate or tricuspidate 

 spines, which come to view at oue or the other end of the 

 cell as it is more or less inclined from a horizontal position. 

 End view triangulai', angles slightly produced, apices tri- 

 dentate ; sides nearly straight, or slightly convex. 

 Diameter 7.5-9.5 /^. 



