﻿378 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



is closely covered with slender pointed papilliform outgrowths of the 

 cuticle, 1-1.5 mm. long, which give a furry appearance to skin. 

 These papillae communicate \vith irregularly zigzag subcutaneous 

 canals, above which the cuticle usually forms slight welts, which have 

 a direction oblique to the longitudinal axis of the dermal rectangles. 

 Each rectangle has its o^vn canal, independent of the others (pi. 19, 

 figs. 4, 5). Beyond the papuliferous area these canals — or more 

 properly spaces, as they are usually branched — can be traced forward 

 half the distance to the head, and also posteriorly, as they are often 

 self-injected mtli yellowish material from the coelom. On the 

 periphery of the papuliferous area a papilla usually appears, first at 

 the anterior end of the canal, next at the posterior end, then in between, 

 imtil there are four or five to each rectangle. Bro\vn or yellow, finely 

 divided material, which is sometimes loose in the canals, is also found 

 in the bottom of the papillae. If the top of the canal is stripped off, a 

 pore at either end is seen to lead deeper into the tissue (arrows in 

 pi. 19, fig. 4). If ordinary ink is forced /ro7» the coelomic side into the 

 pores that exist at intersection of longitudinal and transverse muscle 

 bands, it appears in these pores at the ends of the subcutaneous 

 canals but is usually blocked by material already in the canal. The 

 papillae are higlily iridescent in sunlight. The area strongly reminds 

 one of the papularium of a sea star, and the function is probably the 

 same, i. e., respiratory. 



The terminal knob of the body is very short, broadly rounded to 

 sub truncate, and the slight margin is capable of disappearing under 

 distension. There is a conspicuous terminal pore, and the skin, either 

 smooth or longitudinally ridged, is closely beset with microscopic pores 

 of at least two sizes. 



The short introvert is covered with squamiform papillae, which 

 increase in size toward the front, near which they decrease over a 

 narrow zone to the bare zone behind the tentacles. The largest 

 papillae are 0.75-1 mm. in length and breadth. 



The tentacles are composed of very numerous small grooved foliate 

 elements in sub triangular mats or groups, radiating from the mouth, 

 which is ventral to the center. There are seven of these from which 

 ridges of tissue converge to the mouth, two dorsolateral, two lateral, 

 and two ventral, the odd one being the middorsal and much the 

 largest. On the periphery of the crown the space between the major 

 groups is filled in with one to tlu-ee small groups of tentacles, which 

 probably increase in number as grov.th proceeds. 



The anus is equivalent to about five muscle rings (not clearly 

 dift'erentiated) behind the posterior papillae of the introvert. 



Interiorly the longitudinal muscles form flat bands becoming 

 angular in section only when the body is much constricted. The 



