342 Mary R. Ckavens aud Harold Heath, 



or spherical nucleus. These latter elements are usually placed about 

 the middle of the cell and especially in the dorsoventral bands form 

 conspicuous groups (Fig-. 18, 20). 



Concerning- the cirri Verrill writes (p. 448): ''From the back 

 part of the head, or commencement of the neck, a long, tapering 

 cirrus arises on each side. The cirri have a thick, roundish, muscular 

 base from which they taper to a long, slender, lash-like, often coiled 

 tip. These organs seem to be mere extensions of the muscular walls 

 of the body and are not hollow". This description applies closely 

 to N. pelagica; the cirri are mere expansions of the body wall, and 

 while they are not hollow in the sense of containing an open cavity 

 their muscle layers are tubular and the small central lumen is filled 

 with parenchyma which is continuous with that of the body. The 

 nerves, as is more fully described in the section on the nervous 

 system, do not pass down this axial portion but are eccentrically 

 distributed in the outlying muscular walls. 



In the head region the parenchyma is a conspicuous feature but 

 more posteriorly in the intestinal region it becomes scant in amount. 

 In the neighborhood of the brain several lacunae of relativly small 

 size are developed within it and in the cirri it forms a central canal 

 extending nearly to the free extremitj^ Elsewhere it constitutes a 

 comparativly uniform felt work supporting- the organs of the body 

 and 'extending in between the muscles, especiallj^ the longitudinal 

 layer, which becomes developed into a number of conspicuous bands 

 visible both in sections and surface views. The cell elements 

 composing it are small, with dense nuclei, and occasionallj' in favor- 

 able situations may be seen to possess an irregular often stellate 

 form. 



As noted in a preceeding paragraph the epithelium is lacking 

 from the greater part of the body and it is accordingly not possible 

 to determine if the epithelial gland cells undergo any modifications 

 especially in the anterior end of the animal. From sections and 

 surface views it appears certain that cephalic glands are lacking 

 in this species and submuscular gland cells, if they exist at all, are 

 comparativly rare. Here and there over the body, especially in the 

 keel-like projection at the sides of the animal, minute cells occur 

 which show a decided affinity for logwood dyes. Some of these are 

 imbedded in the circular muscles while others extend into the super- 

 ficial layers of the longitudinal bands but all are connected with 

 the basement layer above by what appears to be a delicate duct 



