306 THE AMERICAN NATURALIST. [VoL. XXXVI. 
Only advanced buds are visible from the dorsal aspect 
(Fig. 7). These completely cover the young buds on the ven- 
tral side and overlap so that the heads of all the advanced 
buds are concealed... Occupying the most. dorsal position 
amongst the advanced buds is the attenuated and rapidly 
diminishing caudal extremity of the stock. It is much like the 
buds in general aspect, and further resembles them in contain- 
ing sperm cells, which are absent in all portions of the stock in 
front of the proliferating region. It differs from the buds in 
possessing (1) a heavily ciliated continuation of the alimentary 
canal (Fig. 7, aie); 
(2) the anus, and 
(3) differs in lacking 
cephalization. In 
every respect except 
that it contains 
sperm cells, it re- 
sembles a regener- 
ated posterior 
extremity. It pos- 
sesses twenty -four 
somites, including 
the pygidium. The 
proliferating region 
is therefore this 
number of somites 
in front of the pos- - 
terior extremity. As 
ANN) Fig. 7 shows, the 
ges o. — Frontal section of a portion of a full-grown budof attenuated posterior 
A asclcule (ec), muscles Yay en coer a Mas almost 
glands (27). The intersegmental dissepiments and median ag much the appear- 
strand (s.) are indicated. x 75. * 
ance of being an 
appendage to the budding zone as any of the mature buds.! 
It is worthy of note that into this region the deep intestinal 


s This attenuated posterior extremity is. probably a permanent feature. I have 
found it in every entire speci Xf T. gemmipara I have collected on the Cali- 
fornia coast, but the number collected is small. i 
