444 
F. A. POTTS. 
advances and fills the hollow processes formed by the ectoblast. 
It lies at first in close association with the ventral surface of 
the stolon. 
(3) The inesoblast of the stolon proliferates and segments. 
The first appearance of segmentation is the formation of septa. 
(4) The invasion of the stolon by two bundles of muscle- 
fibres in direct continuation with those of the stock, and a 
single ventral nerve-cord, also an outgrowth of the corre- 
sponding structure in the stock. 
(5) The segmentation of the epiblast of the stolon and the 
formation of the structures derived from it (setfe, etc.). The 
gonads are formed as lateral outgrowths from the central 
mesoblastic mass. 
With the growth of the stolons the proliferating cushion 
is gradually absorbed. 
Liteeature. 
1. .rolinson, H. P. — “ The Polycha4a of the Puget Sound Region." 
‘ Proc. Boston. Soc. Nat. Hist.,’ vol. xxix. 1901, pp. 381-437. 
(First description of Trypanosyllis geuiinipara, see p. 40.5.) 
2. “ A New Type of Budding in Annelids." ‘Biol. Bull.,’ vol. ii. 
1901. pp. 336-T. 
3. “ Collateral Budding in Annelids of the genus Trypano- 
syllis,’’ ‘ Ainer. Natural.,’ vol. xxxvi, 1902, pp. 29.5-31.5. 
4. Izi;ka, A. — “ On a Case of Collateral Budding in Syllid Annelid 
(Trypanosyllis misakiensis, n. sp.)," ‘ Annot. Zool. Japan.,' 
vol. V, 1906, pp. 283-7. 
5. Potts, F. A. — “ Methods of Reproduction in the Syllids,’’ ‘ Ergehn. 
Fortschr. Zool.,’ Bd. iii, 1911, Heft 1 (see pp. 14-20). 
EXPLANATION OF PLATES 23 and 23 bis. 
Illustrating Mr. F. A. Potts’ paper on “Stolon Formation in 
Certain Species of Trypanosyllis.” 
Abbreviations. 
ac. Acicula. «. Anus. «(. c. Aliiuentai’y canal, dorf. Dorsal surface 
of stolon, epi. Epiblast. cl. c. Dorsal cirrus, cj. a. Genital appendage 
gon. Gonads. 1. m. Longitudinal muscles. 1. Leucocytes. Leuco- 
