NO. 2164. REVISION OF ROTATORIAN GENERA— EARRING. 555 



body a trianguloid appearance; posteriorly the lorica is constricted 

 in the region of the foot groove and the extreme end is quite narrow. 

 The width of the body over the spurs is equal to the length of the 

 lorica. The spurs are slightly outcurved and very slightly decui-ved; 

 the principal part of the spur is rather narrow, while the base is 

 somewhat abruptly widened and merges gradually with the lorica. 

 The dorsal plate is tectiform and has three pairs of longitudinal ribs 

 or ridges. The medial or innermost pair of ridges are inconspicuous 

 and quite close together, separated by a shallow groove; no definite 

 length can be assigned to these ridges, as they gradually disappear, 

 but they are approximately one-third the length of ihQ lorica. The 

 intermediate pair of ridges are lamellar and project from the dorsal 

 plate as distinct keels, highest in the middle; anteriorly they are 

 nearly parallel and do not quite reach to the collar, while posteriorly 

 they gradually converge and disappear without attaining the pos- 

 terior end of the lorica. The external pair of ridges are not very 

 prominent; they are somewhat wavy and nearly parallel; anteriorly 

 they seem to reach the edge of the lorica, some distance behind the 

 collar, but posteriorly they terminate in front of the spurs. The 

 ventral plate is very nearly flat. The cross section of the body is 

 rouglily a low, obtuse-angled triangle ; the relative prominence of the 

 longitudinal ridges is shown in figure 8. The dorso-ventral depth 

 of the body is less than one-third the length of the lorica. 



The anterior margin is extremely broad, nearly one-half the length 

 of the lorica; there is really no dorsal sinus present, as the anterior 

 points are wholly on the ventral plate, but the frontal margin of the 

 dorsal plate is slightly concave. The ventral sinus is broadly V- 

 shaped and slightly rounded posteriorly; its depth is less than half 

 the width of the anterior margin. There is a very narrow stippled 

 collar, of nearly the same width everywhere ; it is continuous around 

 the anterior opening and does not disappear at the edges of the lorica, 

 as usual. 



The foot groove is ovate, widest anteriorly, its edges slightly con- 

 vergent and gradually disappearing before reaching the posterior 

 end of the lorica. The length of the foot groove is somewhat less 

 than one-third the length of the lorica, its width about one-half the 

 length. The posterior end of the lorica is distinctly tectiform and has 

 a shallow, V-shaped emargination, slightly rounded anteriorly. 



The foot is moderately stout and a little less than one-tliird the 

 length of the body ; the first and second joint are of nearly the same 

 length, while the third is somewhat longer. There is a sensory pit 

 on the last foot joint. The toes are as long as the foot, straight and 

 slender, and taper gradually to acute points. 



Total length, 95 n; length of lorica, 70 ju, width over spurs, 74 /*; 

 width of anterior margin, 30 ju; depth of dorsal emargination, meas- 

 ured from anterior points, 9 /*; depth of ventral sinus, 12 /x; length of 



