NO. 2164. REVISION OF ROTATORIAN OENERA— EARRING. 541 



length of foot, 32-35 n, of last joint, 11-12 n, of toes, 25-30 ju; depth 

 of body in median plane, 30-35 ix; from highest point of dorsal plate 

 to edges of lorica, 40-45 fx. 



Lepadella patella occurs everywhere in weedy pools and ponds, as 

 well as in wet mosses, and is in such places probably the most 

 abundant of all rotifers. On account of its variability it has during 

 its history received a considerable number of names. What the 

 value of these variations may be is difficult to say; in a circumscribed 

 locahty they are usually shght, and it is only when material from 

 widely separated regions is brought together and compared that the 

 different forms are seen to overlap. Only some of the principal 

 varieties have been illustrated. Intermediate forms joining all of 

 these are to be found; but, as stated above, not in the same locality. 



The nearest relative of this species appears to be Lepaclella ovalis; 

 the relative thickness of the body is sufficient to differentiate the two 

 species. In L. patella this is one-third the length of the lorica, while 

 in L. ovalis it is only one-fifth. The anterior opening is also relatively 

 larger in L. patella, and the form of the ventral sinus is quite different 

 in the two species. In L. patella it is roughly V-shaped and widest in 

 front, while in L. ovalis the sinus is rhomboid, with the widest point 

 some distance from the front. 



Metopidia collaris Stokes appears, judging from the figure, to be a 

 synonym of L. patella. In any case the name is not available, as it 

 was previously used by Levander for a variety that is undoubtedly 

 synonymous. Under the name 31. collaris Stokes, Murray fists ^ from 

 Sydney, Australia, the animal figured on plate 91 , figures 3-5. This is 

 drawn from a single mounted specimen given to me by Mr. Murray. 

 Only the lorica is preserved, the foot and toes having disappeared. 

 It is very evidently different from any known LepadeUid, but on 

 account of the defective specimen it seems imdesirable to give it any 

 name. It is figured here to complete Murray's record and also in the 

 hope that better material may eventually be discovered somewhere. 

 The anterior opening is veiy peculiar and so is the broken lateral 

 edge. It is barely possible that this may be due to the preservative. 

 No details of the foot openmg are available. The figure represents 

 only the condition of the specimen and evidently not the normal 

 structure. On the ventral plate there are two short longitudinal 

 ridges quite close together. The dorsal plate has a median ridge, 

 beginning a short distance from the anterior margin and continuing 

 to the posterior point of the lorica. Two subdorsal ridges originate 

 on the anterior points and reach very nearly to the end of the lorica. 

 Length of lorica, 72 fi, width, 45 m; width of anterior margin, 15 n; 

 depth of dorsal sinus, 5 n, of ventral sinus, 18 fx.; dorso-ventral depth 

 of lorica, 30 jjl. 



1 Journ. Royal Micr. Soc, 1913, p. 460. 



