560 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.51. 



of the keel are somewhat concave and meet in the median plane at 

 a rather acute angle, thus forming a pronounced dorsal ridge; there 

 is no distinct lateral groove, as the sides of the keel merge very 

 gradually with the dorsal plate. The cross section of the body is 

 triradiate; the lateral, wing-like portion of the body is very thin. 

 The dorso-ventral depth of the lorica is somewhat less than half the 

 length of the body. 



The width of the anterior margin is a little less than one-third the 

 length of the lorica. No dorsal sinus is present, but the frontal 

 edge of the dorsal plate is slightly concave. Tlie ventral sinus is 

 semicircular; its depth is slightly more than half the width. There 

 is no stippled collar, but the anterior margin is slightly thickened, 

 thus forming a faint, bead-like line around the opening for the head. 



The foot groove is U-shaped, parallel-sided, and rounded anteri- 

 orly; its length is about one- third the length of the lorica. The 

 posterior end of the lorica is bluntly pointed, and projects beyond 

 the point where the sides of the foot groove meet the edge of the 

 ventral plate. 



The foot is less than one-fourth the length of the lorica and rather 

 slender; its three joints are of nearly equal length. The toes are a 

 little more than one-fourth the length of the body; they are very 

 slender and taper gradually to acute points. No dorsal sensory pit 

 has been observed on the last foot joint. 



Total length, 112 ^t; length of lorica 86 n, width 88 ju; width of 

 anterior margin, 26 n; depth of ventral sinus, 15 m; length of foot 

 groove, 30 ix, width, 14 /i; length of foot, 19 /x, of last joint, 7 n; 

 length of toes, 24 /i; depth of body, 36 fx. 



This description is from a single specimen collected by Mr. Mur- 

 ray in New Zealand and sent to me by Mr. Rousselet. It seems 

 to be rare, the records by Bryce, Murray, and Montet being all that 

 I have been able to find. It is possible that it may have been con- 

 fused with L. triptera, with which it has a certain general simi- 

 larity; it is, however, considerably larger and more markedly rhom- 

 boid. 



21. LEPADELLA TRIPTERA Ehrenberg. 



Plate 95, figs. 1-4. 



Lepadella triptera Ehhenberg, Abh. Akad. Wiss., BerHn, 1830, p. 71. 



Metopidia triptera Ehrenberg, Abh. Akad. Wiss., Berlin, 1830, p. 72; Infu- 

 sionsth., 1838, p. 478, pi. 59, fig. 12. — Hudson and Gosse, Rotifera, 

 1886, vol. 2, p. 108, pi. 25, fig. 7.— Wierzejski, Rozpr. Akad. Umiejetn., 

 Wydz. Mat.-Przyr., ser. 2, vol. 4, 1893, p. 246.— Weber, Rev. Suisse Zool., 

 vol. 5, 1898, p. 640, pi. 23, figs. 6-9.— Lucks, Rotatorienfauna Westpreus- 

 sens, 1912, p. 124.— Montet, Rev. Suisse Zool., vol. 23, 1915, p. 339. 



The outline of the lorica varies from nearly circular to broadly 

 pyrifonn; its width is about seven-eighths of the length. The dorsal 



