223 [Wilder. 



a papilla. Taken by themselves, these three cases would be merely 

 curiosities, but there are on record several cases where such or similar 

 papillae have accompanied an imperfect development of the ear. In 

 Otto's " Monstrorum descrlptio anatomica," Plate iv, Fig. 3, is repre- 

 sented a foetus with a natural left ear, but small right ear, with several 

 such paplllas in front of it and over the lower jaw ; and Fig. 2 repre- 

 sents another foetus in which the right ear was normal, but in place of 

 the left was a large papilla, looking as if the meatus had been everted- 

 I am informed by Prof. Wyman that there may be traced a se- 

 ries of abnormal appendages, from such simple papillae as those de- 

 scribed, at the one extreme, to a more or less completely formed foe- 

 tus at the other ; so that the papIHae may be regarded as the mini- 

 mum of development for a twin. The absence of the lobule in both 

 cars Is instructive, when it Is remembered that this portion of the ex- 

 ternal ear Is the last to appear in the development of the embryo, and 

 that it Is the first to disappear among the mammalia below man. 



Prof. H. James Clark presented a paper " On the Yorticel- 

 lidan parasite ( Trichodina pediculus Ehr.) of Hydra." He re- 

 marked that in its healthy, unrestrained condition, Trichodina 

 is very dissimilar from the hitherto published representations 

 of it ; that it has a deep, asymmetrical, cyathiform, or dice- 

 box shape, with an kregular and longitudinally furrowed and 

 plicated exterior ; a greatly depressed cupuliform disc^ along 

 the margin of which a single, spiral row of vibratile cilia or 

 "vibratory organ " is attached; that the so-called vestibular 

 lash, or " bristle of Lachman," is an optical illusion arising 

 from a foreshortened or edgewise view of the row of cilia at 

 the mouth of, and within the vestibule ; that the posterior, 

 truncate end of the body is margined by a distinct, annular 

 velum, immediately behind which, and arising from the same 

 basis, is a complete circle of vibratory cilia; and finally that 

 the so-called " adherent organ," or apparatus of hooks and 

 radii consists, firstly, of a distinct, separate, annular border, 

 of which the opposite faces are dissimilarly striated by per- 

 fectly straight, transverse ridges ; secondly, of a complicated 

 circle of separable hooks, which is applied to the posterior 

 face of the striated, annular border, along its proximate edge ; 

 and thirdly, of a series of T-shaped radii which He, one by 

 one, opposite the several hooks, and converge toward the axis 

 of the basal plane of the body. 



