ANDREWS: ANNULUS VENTRALIS. 
441 
Removal of the annulus leaves a soft protruding surface that exudes 
blood which hardens into an irregular brown mass that covers the 
wound till the time when the animal next sheds. Then, in a few cases r 
it was found that upon the base whence the conical annulus was cut, 
a new, but very imperfect annulus had been formed. As the mass 
removed is part living tissue as well as exoskeleton there is some 
regeneration of lost living tissue; there is also the making of a new 
exoskeleton somewhat as would follow in the case of normal shedding 
without previous cutting away of the annulus (Andrews, : 06 ). 
The tissue that normally makes the complex exoskeleton of the 
annulus and has also the above slight regenerative powers, seems to 
be one syncytium throughout the entire annulus, hollowed out for 
blood vessels and lacunae and smaller cavities, full of blood and modi¬ 
fied on the surface as an epidermis. In some cases parasites were 
very abundant in all these blood spaces. 
The epidermal part forms everywhere a complete covering of proto¬ 
plasm next to the exoskeleton with numerous nuclei in it and cell 
walls poorly indicated by the methods used. As shown in figures 12 
and 13 (pi. 44), and 15 (pi. 45), the epidermis is continuous with the 
underlying network of connective tissue that has blood in its meshes. 
In figure 12 (pi. 44) the same continuity is shown in a preparation in 
which the cellular character of the epidermis was unusually pronounced. 
The external face of the epidermis presented various relations to the 
exoskeleton. Often when the epidermis was artificially drawn away 
from the exoskeleton, there was a finely fibrous mass, as of a coagulum, 
extending out from the epidermis, as indicated in figure 12 (pi. 44). 
In other cases the epidermis almost in contact with the exoskeleton 
sent out long delicate filaments that seemed to coincide with delicate 
tubules passing through almost all the thickness of the exoskeleton. 
Such tubules were seen chieflv in the walls of the tuberosities and not 
V 
in the walls of the trumpet. The very much grosser tubules passing 
to setae are almost entirely absent from the entire annulus though a 
few setae were seen near the extreme outer edge as represented on the 
right of text-figure C. To these few hairs special strands, presumably 
nervous, pass through the connective-tissue network. Otherwise no 
nerve tissues and no gland tissues were recognized in any part of the 
annulus. 
In some cases the sections seem to have been cut when the epi¬ 
dermis was active in making exoskeleton. That is, the very regular 
