544 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 51. 



width, 18 n; length of foot, 20 li, of terminal joint, 8 m; length of 

 toes, 24 n; depth of body, 28 ijl. 



Type. — Cat. No. 16827, U.S.N.M., was collected in sphagnum 

 growing in the old gravel pit at Hyattsville, Maryland. It has also 

 been found in a collection from the United States Bureau o{ Fisheries 

 station at San Marcos, Texas. 



6. LEPADELLA QUINQUECOSTATA (Lucks). 



Plate 95, figs. 5-8. 



Metopidia quinquecostata Lucks, Siisswasserfauna Deutschlands, pt. 14, 1912, 

 p. 189, text fig.; Rotatorienfauna Westpreussens, 1912, p. 126, text fig.— 

 Murray, Jouni. Royal Micr. Soc, 1913, pp. 450, 460, pi. 19, fig. 9. 



Lepadella quinquecostata Earring, Bull. 81 U. S. Nat. Mus., 1913, p. 64. 



The lorica is distinctly pyriform in outhne, narrowing perceptibly 

 toward the head. The dorsal plate is, diregarding for the moment 

 the lateral ridges, composed of two fiat plates, meeting at an obtuse 

 angle in the median line. The ventral plate is slightly concave and 

 the cross section of the body approximately triangular. The dorsal 

 plate has a median ridge, beginning a short distance behind the 

 stippled collar as two indistinct, convergent lines, uniting about 

 halfway down the dorsal plate and continued as a single, incon- 

 spicuous ridge to the extreme end of the lorica. Two ridges begin 

 near the anterior points of the lorica and, converging very slightly 

 throughout their length, continue a short distance past the lateral 

 antennae, where the points turn sharply in toward the median ridge 

 and then disappear. A second pair of strongly curved ridges, start- 

 ing back of the collar and outside those already described, foUow a 

 course roughly parallel to the edges of the lorica and terminate just 

 in front of the lateral antennae. These lateral ridges are all most 

 prominent at their middle and decrease toward the ends. Their 

 form will be understood from figure 8. The width of the lorica is 

 two-thirds and the depth of the body a httle less than one-third the 

 length of the lorica. 



The distance apart of the prominent anterior points is one-fourth 

 the length of the lorica; the anterior sinus is broadly U-shaped, and 

 its depth equals one-half its width. The ventral sinus is approxi- 

 mately V-shaped, its posterior angle shghtly blunted, and the sides 

 decidedly concave; its depth is a little less than its anterior width. 

 The stippled collar, which is present on both the dorsal and the 

 ventral plate, is very narrow on the median line and increases gradu- 

 ally in width as it disappears toward the sides of the lorica. 



The foot groove is one-third the length of the lorica ; it is rounded 

 anteriorly and very nearly parallel-sided; the sides are occasionally 

 shghtly pinched in at the base of the foot, as shown in the ventral 

 view ; but as a rule this narrowing does not exist and the sides cui've 



