210 ARTHUR E. SHIPLEY. 
new ones appear. As they have no lining of any kind, such a 
closing would leave no trace. 
As Schneider,! Hamann,” and Kaiser® have shown in the 
species investigated by them, the lacunar system of the intro- 
vert is completely shut off from that of the neck—if it be 
present—and of the trunk by a fold inwards of the cuticle 
which cuts the subcuticular tissue in two. I have not been 
able to find any such cuticular ring in the species in question, 
but the state of preservation of my specimens does not allow 
me to say definitely that it does not exist. 
The lemnisci are two elongated sac-like prolongations of 
the subcuticular tissue which are attached anteriorly to the 
skin at the junction of the head and collar. They extend back- 
wards to the extreme posterior end of the body, and are slightly 
bent so that a longitudinal section may cut them in two or 
three places (fig. x111). Histologically they are composed of 
the same substance as the subcuticle in direct continuity with 
which they arise, and they are traversed by a similar system of 
canals. Physiologically they seem, as Hamann suggests, to 
act as reservoirs for the fluid of the canal system of the intro- 
vert; when the fluid they contain is forced into the spaces of 
the introvert the latter is everted. It is withdrawn again into 
the body by special muscles. In most species the canal system 
of the lemnisci opens into that of the introvert in front of the 
cuticular ring, and is thus completely independent of that of 
the trunk. If we assume that the head of my species corre- 
sponds with the introvert of other forms which have lost its 
introvert sheath, the lemnisci open into the same region of 
the skin as they do in other Acanthocephala. 
The nuclei of tae subcuticle and of the lemnisci are very 
remarkable; they cc:.espond in structure with those described 
by Hamann in Neorhynchus claveceps, in which species 
according to this observer both the skin and the lemnisci retain 
in the adult their embryonic condition. As in Neorhynchus 
1 «Arch. Anat.,’ 1868, p. 584. 
2 «Die Nemathelminthen,’ Hefte 1 and 2, Jena, 1891 and 1895. 
3 * Bibl. Zool.,’ Heft 7, 1892, p. 1. 
