UKNATELLA GRACILIS, A FRESH-WATER I’OLY/OAN. 
9 
specimens are found in wliich, instead of one of the cups, a branch is givcm off, a« 
represented in figure 4. 
In the simplest condition Urnniella is observed as a ])olyp-hell attached to a simple 
cylindrical pedicel, thus resembling the ordinary appearance of an individual P&Ueelliud. 
Such a specimen is represented in figure 5, occurring in the usual way as a pair of 
individuals springing from a common disk of attachment. Tlie simple pedicc'l is much 
longer than the corresponding segment in the more divided stem of UnxifeJht, but is 
otherwise of the same character. It appears as a solid column, translucent white, and 
consists of an internal cord or axis, longitudinally striated and muscular in nature, 
invested with a transparent chitinous integument. The pedicel is highly flexible, 
spontaneously bends in all directions, but appears to bo feebly if at all contractile. 
Other specimens of Urnatella were observed in which one or both pedicels, as in 
those just described, were more or less distinctly divided each into two segments, as 
rcpre.sented in woodcut 1, and in figarres 6, 7, of Plate I. The.se ('vid('ntly indicate 
the origin of the segments of the stem of Urnatella through continued growth and 
the process of successive division of the originally simple pedicel. Abundance of 
specimens of Urnatella, occur rvith segments ranging from the smalk'st to the greatest 
number, clearly indicating the successive production of the segments through the 
process of division, very much in the same manner as in the production of the 
proglottides of tape-worms from a scolex. 
In the first r iew of Urnatella one might suppose that the st'gments of the stem 
represented so many distinct polyps as in Pliimatelh(, but examination leads to tlie fact 
that the terminal polyp is the only one of the series. 
In the production and growth of the segmented stems of Urnatella, after the first 
division of the original simple pedicel, which is a cylindrical column, the segments 
distally from the latter and its polyp-bell, successively assume tlie char.icteristic urn- 
like shape observed in the more matured specimens, and as repre.simted in figures 1. 
2, 4, 8. In most matured specimens observed the stems rarely consisted of mon' than 
a dozen segments, including the polyp-hell. 
After the division of the simple pedicel of the young Urnatella into two or more 
segments, the various specimens observed would appear to indicate that the one or 
tw^o st'gments next the bell put forth buds in pairs laterally near the upper end or 
base of the segments. These buds appearing as spheroidal or o>-oidal pro< es.ses then 
develop and grow into branches, commonly consisting of a bell and pedicel like the 
early parent. In like manner specimens go to show that secondary branches are 
produced in a similar manner from the primary ones. AVoodcuts 3 and 4 repress nt 
examples of such specimens just described. 
From the usual mode of branching of Urnatella, that is to .sj.y. from the branches 
coming off from the two segments of the stem next the polyp-hell, and from the nsnal 
absence of branches from the succeeding urns, with the presenc.' ol the appanmt 
