300 THE AMERICAN. NATURALIST: [Vor. XXXVI. 
T. gigantea has the great intestinal diverticula so conspicuous 
in 7. ingens and in 7. gemmipara (Fig. 16). . The prostomium 
of 7. gigantea is also of simpler form. 
Unfortunately the. delicate tail buds of this formalin- -pre- 
served specimen were somewhat macerated and broken in 
transportation ; most of them had fallen off, and probably some 
of them were missing, when the specimen came into my 
hands. They number about 30, and are all at about the 
same advanced stage of development. Each bud exhibits the 
external characters of the stock. Its somites have nearly 
the same proportions ; its parapodia, with their diminutive cirri 
and setz (Fig. 5), are of the same pattern, with the slight 
difference that the appendages of the setze have a small tooth 
and minute serrations on the concave side, while these are 
absent in the setae of the stock (cf Figs. 3, 4). The average 
length of the buds is 5 mm., their breadth 2 mm., their 
thickness 0.5 mm. The number of their somites is approxi- 
mately 25. 
Each zooid is divided into a ERA series of coelomic spaces 
by the intersegmental dissepiments and a minute median 
tubular structure, which I interpret as a rudiment of the ali- 
mentary canal (Figs. 5, 6, a/.c.). The coelomic spaces, includ- 
ing even the parapodial cavities (Fig. 5), are packed full of 
eggs, which possess very large nuclei and nucleoli, the latter 
usually vacuolated (Fig. 6) ^ No ova have been found in the 
parent stock. The longitudinal muscular system of the bud is 
not highly developed (Figs. 5, 6, Zm.), and no circular muscu- 
lature was detected. | Circular muscles are very slightly devel- 
oped in the stock. There is a slender transverse muscle 
extending from the lateral body wall to the nerve cord (Fig. 6, 
£m.) This, however, I suspect is not so much a separate muscle 
as a portion of the very extensive system of septal muscles. 
A. dorsal and a ventral blood vessel (Fig. 6, dv, v.v.) are 
seen close to the digestive tract. The ventral vessel with its 
coagulum. is apparently of uniform diameter throughout its 
course, while the- dorsal vessel is segmentally constricted 
(Fig. 6 "pe a constricted. € No lateral. branches 
have been detected 
