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ROBERT SCHARFF. 
cation of hypodermic cells, I do not attach much importance 
to this. Hence I must still regard the view that these dermal 
spikes are supplied with special nerves as doubtful. A further 
examination to clear this is much needed. 
Ehlers, 1 who was the first to describe the little cones on the 
proboscis, saw quite correctly that the hypodermic layer was 
continued into their interior, but he believed that they were 
hollow and that the hollow cavities might possibly communicate 
with the perivisceral space. Graber, 2 on the other hand, mis- 
took the hypodermis for a part of the circular muscles of the 
proboscis, and describes the spikes as being filled up with their 
prolongations. In their description of Priapulus bicau- 
datus Daniellsen and Koren 3 agree with Ehlers in looking 
upon the spikes as hollow outgrowths invested with an internal 
lining of epithelium. I will give the following passage in their 
own words : — “ In the hollow of every spike, at the base, is 
seen an almost round, comparatively large gland (figs. 4, e. ; 5, e.) 
composed of connective tissue, covered internally with round 
cells (figs. 4, /. ; 5 ,/.), and from the arcuate portion of these 
issues the excretory canal (fig. 4, g .) which, passing up through 
the hollow of the spike (figs. 4, h. ; 5, g.), disembogues exactly 
where the epithelial integument of the latter terminates (figs. 
4, i. ; 5, h.). The gland contained a viscid, granulous, pellucid 
substance, which we observed once or twice in the aperture at 
the free extremity of the spikes.” 
There is no doubt that these authors have seen Horst's 
“ Integumentalhohlen ” with their containing blood-corpuscles, 
which are the glands they mention. Neither Horst nor 
myself have seen anything of an excretory canal. 
Although Saenger’s figures leave very much to desire, his 
investigations seem to have been made with great care, and it 
is unfortunate that his works, being written in Russian, are 
practically inaccessible. He states on p. 212 of the work cited 
before, that the interior of the spikes contains hypodermic 
1 Ehlers, loc. cit., p. 221. 
2 Graber, loc. cit., p. 62. 
3 Daniellsen and Koren, ‘ Den Norske Nordbavs Expedition,’ p. 11. 
