Vol.1.] h'ilfi i- I 'hiris . — i'.iili rn/nn iistn . 1 i '< 



the oral field backward to the ciliary girdle, so thai the sides 

 form an angle much less than a right angle with the plane of 



this circle. 



The tentacles of the longitudinal bands are short and are 

 capable of very little if any movement. They stand out from 

 the surface of the body, with an inclination, however, toward the 

 circumoral field. As the number of these tentacles on each por- 

 tion of the band is quite constant, it is worth while to enumerate 

 them. There are about eight on the descending limb of both 

 the ventral lobe and the anterior dorsal lobe, and six on the 

 ascending limb of each of these lobes. There are about three on 

 each side of the narrow lateral isthmus connecting the anterior 

 and posterior transverse portions of the oral field. A single 

 pair of tentacles, somewhat shorter than the longest ones of the 

 series above described, is present at the narrowest part of the 

 lateral lobe. 



From our interest in the locomotion of the animal we have 

 been led to study the cilia of the external surface with somewhat 

 more care, it would appear, than has hitherto been bestowed 

 upon them. These cilia are of three quite different sizes. The 

 smallest and most abundant are those of the longitudinal bands. 

 These have an approximate length of .007 mm. They are situated 

 on the anterior longitudinal bands, from which it results that 

 since the tentacles are looped-out portions of the band, each 

 one is not ciliated on its entire surface, but only on opposite 

 sides, PI. XVIII, Fig. 8, tent. The greater height of the 

 ectodermal cells on which the cilia of these bands are borne, and 

 also the distinctness of their nuclei, are shown in this figure. 

 The cilia ai-e entirely confined to these bands. This fact is prob- 

 ably taken for granted by other writers on tornaria, but we 

 have nowhere seen it definitely so stated. It is rather interesting 

 in view of the uniform ciliation of the proboscis of the adult 

 entei'opneust, which is derived from the region of these bands 

 of the tornaria. 



In the ciliary girdle there are two distinct sizes of cilia. The 

 smaller ones have a length of .08 mm., while the larger ones, the 

 tiagelliform cilia, as Ave may call them, are about .267 mm. long. 

 The tiagelliform cilia occupy the middle portion of the band, the 



