128 



II. JAMES-CLARK OX THE ANATOMY 



outline. The nucleus (n) is cut across its middle. The sigmoid figure of the vestibule (v) 

 and oesophagus (o), being seen as it were edgewise, is foreshortened upon a flat surface 

 The lettering is the same as that used for the figures of the plate. 



Explanation of Plate IV. 



The corresponding parts in all of the figures of the plate and the wood-cut are lettered alike, as follows ■ _ a anus • 

 b vibratory crown; b\ begmnmg of the vibratory crown ; V, end of the vibratory crown within the vestibule 1° 

 furrow of the vibratory crown ; c, the bottom of the cupuliform disc; c\ the side of the disc; c\ the side of the disc 

 roled back; a a front view of the disc; c\ the "inclined plane" which lies upon the cornice-like oblique projection 

 below the aperture of he vestibue; cv, the contractile vesicle; d, the peristome opposite the vestibular aperture 

 V the dorsal region of the penstome; cP, the inrolled edge of the peristome; <P, the peristome at the edge of The 

 inclined plane c<) ;_ d\ the penstome where it becomes blended with the general surface of the body /the fir 

 turn, or ventral region of the peristome ; e, the lumen of the edge of the row of vibrating cilia, hitherto' supposed to 

 be a dist.nct vestibular lash (« bristle ") ; /, the profile of the velum ; f\ the free edge rf the ^1 /t s 



edge or line of attachment of the velum ; g, the basal cilia-crown ; h, the hooks of the adherent organ //the cirtle 

 formed by the bases of the hooks , *• the spur of h ; P, the horizontal limb of the hook ; i, the rali £, '£%£ 

 shaped pmce ; .» the head of the same ; i\ the "faint membrane" or web of the T-shaped radii • i* the Ln t 

 the nail-shaped piece ; h, the crest of the hooks ; 1, the profile of the « striated membrane ; • P, the distal ed^e of lie 

 last ; I , the coarser stn* of the same, on its front face ; P, the proximal edge of the same ; P, P, a portion of le 

 posterior face of the striated membrane show.ng the finer striae ; m, the mouth of the vestibule; n, the nucleus or 

 reproductive organ ; n, the eft end of the nucleus ; o, the oesophagus ; o\ the bottom of the same ; p, the outer and 

 p\ the inner walls of the body ; , digestive vacuole ; r, longitudinal ridges on the surface of The body • ,' he 

 general digestive cavity ; v, the vestibule. J ' ' 



All of the figures represent the whole or portions of Trichodina pediculus Ehr 

 diam. ig ' L A " indiVi,1Ual hl the fl ' IleSt degree ° f ex P ansi "»- This is the most common form of the animal. 200 



Fig. 2. Another, less frequent form of a fully expanded individual. 200 diam. 



