NO. 2164. REVISION OF ROTATORIA^ GENERA— EARRING. 54? 



vergent ridges, which do not reach the end of the lorica. Two 

 curved ridges, nearly parallel to the edges of the dorsal plate, begin 

 at about mid-length and terminate just above the lateral antennae. 

 This pair of ridges is frequently absent. The ventral plate is nearly 

 flat. The cross section of the body is approximately semicircular; 

 the dorso-ventral depth is a httle more than one-third the length 

 of the lorica. 



The width of the anterior margin is one-fourth the length of the 

 lorica. The dorsal sinus is broadly U-shaped; its depth is a Httle 

 more than half the anterior width. The ventral sinus is semi- 

 eUiptic, shghtly pointed posteriorly; its depth is two-thirds of the 

 width. A stippled collar is present on the dorsal plate ; the ventral 

 plate may have a very faint collar, but is usually without any. 



The foot groove is one-third the length of the lorica and of elongate 

 ovate form; its width is a httle less than one-half the length. The 

 foot is moderately stout and about one-fourth the length of the body. 

 No sensory pit has been found on the terminal joint. The toes are 

 one-third the length of the lorica, very slender, and nearly straight. 



Total length, 144 /x; length of lorica 109 n, width 72 /x; width of 

 anterior margin, 27 ix; depth of dorsal sinus, 15 n, of ventral sinus, 

 18 fjL] length of foot groove, 38 ix, width, 16 n; length of foot, 26 fi; 

 length of toes, 35 n; depth of body, 42 fx. 



Lepadella acuminata is of world-wide distribution and usually 

 fairly common. 



9. LEPADELLA DACTYTJSETA (Stenroos). 



Plate 92, figs. 1-3. 



Metopidia dactyliseta Stenroos, Acta Soc. Fauna et Flora Fennica, vol 17 



1898, p. 165, pi. 3, fig. 1. 

 Metopidia roUenhurgi Lucks, Rotatorienfauna Westpreussens, 1912, p. 127, 



text fig. 

 Lepadella rottenburgi Harring, Bull. 81 U. S. Nat. Mus., 1913, p. 65. 



The body is subrhomboid in outhne and unusually narrow posteri- 

 orly; its width is two-thirds of the length of the dorsal plate. 

 The dorsal plate is strongly convex and the ventral plate shghtly 

 concave ; the cross section of the body is nearly semicircular. 



The anterior margin of the dorsal plate is without any sinus and 

 usually shghtly convex; the ventral sinus is V-shaped, with shghtly 

 convex sides, which meet posteriorly in a fairly sharp point. The 

 width of the anterior margin is one-third the length of the lorica; 

 the depth of the ventral sinus is a httle more than haJf the width of 

 the anterior margin. There is no stippled collar, but an incon- 

 spicuous hne parallels the sides of the ventral sinus. 



The foot groove is rather short, about one-fourth the length of the 

 lorica, and unusually narrow, its width being little more than half 

 the length. The sides of the foot groove converge slightly toward 



