94 EDWARD POTTS : 



mined whether or not it is possible for it even to reattach its 

 pedal disc after removal. We are, therefore, limited to obser- 

 vation by direct light only, unless the larvse, to be presently 

 described, can be induced to plant themselves upon some 

 transparent support that may either be removed to the stage 

 of our microscope or to which the microscope ma}^ be applied. 



The initial condition of this larva may be described as 

 follows (See Plate I, Figure 2) : A slightly swollen place may 

 be seen at the side of one of the older hydroids involving 

 about one-third of its length, marked at its upper end by a 

 pronounced notch or depression and at the other extremity, 

 less conspicuously, by another, about the same distance from 

 the end of the branch or the point of attachment. The upper 

 notch deepens very rapidly into an evident constriction that 

 progresses sublongitudinally downward, the wound healing as 

 the cells separate, tapering at the lower end, but finally round- 

 ing out to become nearly as large at one end as at the other. 

 The gemmation or asexual reproduction of this larva has 

 taken about eight hours. 



Agreeing with Dr. Ryder's excellent drawing (Plate I, 

 Figure 2) from a median longitudinal section, and with my 

 own diagram (Proceedings of the Delaware County 

 Institute of Science, Volume II, Number 2, Figure 7), 

 it must be noticed that though the position of the larval bud 

 is, from the first, well marked at both extremities, as limited 

 to the middle third of the hydroid body, the actual constric- 

 tion begins at the frontal end of the larva : destined. Dr. 

 Ryder says, to become the capilulum of the new hydroid ; that 

 the larva increases in length during segmentation, and, near 

 the proximal end, tapers gradually in a somewhat ragged 

 fashion, the parental tie continuing as a hair-like thread, 

 until the last cells have parted, when this extremity becomes 

 rounded out, leaving also the wounded side of the parent as 

 perfect as ever (See Plate I, Figures 3 — 7). 



If its birthplace has been upon the upper surface of a stone 

 it may, when liberated, become entangled in, or protected by, 



