74 University of California Publications in Zoology [Vol. 13 



with the surface of the body and the bases and extremities of both lips 

 are continuous with the ectoplasm of the body. Internal to the inner 

 lip and between the inner and outer lips are deep furrows termed 

 respectively the inner and outer dorsal furrows (i. d. fur. and o. d. fur., 

 fig. B; pi. 4, figs. 3, 4). In the inner furrow, which is bounded ex- 

 ternally by the inner dorsal lip and internally by a portion of the an- 

 terior end of the body to be described later as the dorsal disk {d. disk, 

 fig. B; pi. 4, fig. 3) are to be found the bases of the dorsal mem- 

 branelles. These dorsal penicillate membranelles, strong and vigorous 

 in life, measure from one-twelfth to one-eighth of the entire length 

 of the body and number regularly twenty-six or twenty-seven. Each 

 membranelle consists of from fifty to seventy-five cilia and has the 

 appearance of a very long, fine camel 's-hair brush. It is almost certain 

 that a part of the ciliary processes composing each membranelle springs 

 from the ectoplasm of the dorsal disk. These origins are termed 

 anterior ciliary roots (ant. cil. r., pi. 4, fig. 3). The larger number 

 of these ciliary processes have their origin in the ectoplasm posterior 

 to the outer dorsal groove, however, and these are designated as the 

 posterior ciliary roots {post. cil. r., pi. 4, fig. 3). 



In heavily stained sections there appear at the junction of the 

 anterior and posterior roots slight enlargements, which by iron-alum 

 haematoxylin are stained more intensely than the root strands and by 

 Mallorj^'s connective tissue stain show the peculiar bright red which 

 is characteristic of nerves stained by this method in amphibian tissue. 

 In the living condition the cilia of each membranelle cling together 

 as do the hairs of a wet camel 's-hair brush, but in the fixed specimens 

 which have been washed in alcohol these cilia may fluff out as do the 

 hairs in a dry brush. In many cases the cilia composing each brush 

 appear to be twisted spirally like the stripes on a barber's pole. The 

 motion of these ciliary brushes or penicillate membranelles will be 

 discussed later under observations on living material. 



Adoral locomotor apparatus. — The adoral locomotor apparatus, or 

 adoral membranelle zone (ador. m., figs. A, B, C; ador.m.z., pi. 3, 

 fig. 2; pi. 7, figs. 20-22, 33) is much the more complicated of the 

 two zones. This apparatus, in so far as I am able to determine, has 

 never been correctly figured nor described for the species ecaudatum. 

 Briefly, the adoral locomotor apparatus consists of two rows or circles 

 of cilia, an outer circle composed of larger, heavier membranelles 

 along which the wave of contraction passes from left to right, and an 

 inner circlet of smaller, finer cilia along which the waves pass from 



