STAURASTRtTM. 141 



St. Brebissonh, Arch. Plate XLV, figs. 5, 6. 



Cells very mar St. tdiferum, but much larger; semioells 

 more elliptic and aculei proportionately smaller. 

 Diameter (]'2 ;>.. 



Florida, the only habitat hitherto found. 



St. setigerum, Cleve. Plate XLV, figs. 26, 27. 



Semicells broadly elliptic bristly; the bristles, or more 

 properly aculei, have a firm base and sting-like apex ; they are 

 arranged on the margins, with two longer, and stronger, 

 diverging ones <>n each lateral angle. 



Diameter with aculei 45 ".; without aculei *_'"> a. 

 Not north of Florida, as far as I could discover. 



St. Saxonicum, Bulnh. (Nol Reinsch's form). Plate XL V, figs. 



:;: > >, 34. 

 Large, spinous; semicells elliptic, evenly aculeated over the 

 whole membrane; end viev triangular, sides straight or 

 slightly concave. 

 1 diameter 68 75 ". 



Budds Lake, N. J. Compare note. Sit. aculeatum. 



St. echinatum, Breb. Plate XLV, figs. 31, 32. 



Small, a- long as broad, finely aculeated; semicells elliptic ; 

 end view triangular, angles broadly rounded, sides straight or 

 lightly convex ; whole membrane except the centre of the 

 semicells, aculeated ; 710 aculei to a side, end view. 



Diameter 27-30 ". 



Not infrequent in pools and ponds. New Jersey, Pennsyl- 

 vania and other State-. 



St. PECTEN, Perty. Plate \LY. figs. 35, 36. 



This looks like and probably is a depauperated variety of the 

 last, St. echinatum. 

 Diameter '2<> ;>.. 



Denmark Pond, Passaic County, X. J. 



St. hirsutum, (Ehrb.) Breb. Plate XLV, figs. 19-21. 



About as long- as broad, more or less densely covered with 

 thin, short, even, hair-like spine- ; semicells elliptic or sub- 



