Vou. 2] Ritter—The Pelagic Twnicata. 65 
mens, 70 mm., 76 mm., to 80 mm. Test variable, in some thin 
and soft, particularly anteriorly; in others, thicker and firmer, 
particularly posteriorly; a number, from eight to twelve, more 
or less regular, longitudinal, serrated ridges running from the 
atrial end forward a variable distance, but most prominent over 
the nucleus. Branchial orifice with two lips, of which the dorsal 
is distinetly the higher. Atrial orifice also with inconspicuous 
dorsal and ventral lips. Body muscles nine, confined to the 
dorsal side and reaching down laterally scarcely half way to the 
endostyle, where they terminate abruptly. First three anterior 
body muscles confluent dorsally; all the muscle bands distinctly 
broader dorsally. A constrictor muscle in the dorsal lip, and 
one in the ventral lip, both terminating behind the angle of 
branchial orifice, where the ends cross each other and extend a 
short distance beyond the point of crossing. Atrial orifice with 
six or eight muscles of a few fibres each, those of the dorsal and 
ventral lips terminating at the angles, where they cross one 
another. Endostyle slender, straight, extending from the level 
of the angle of the branchial orifice back to the intestine, on a 
level with the eighth muscle band. ‘‘Gill’’ long, narrow, and 
nearly straight, extending from a little in front of the first 
muscle band to the ninth band. Hypophysis horseshoe shaped, 
its plane nearly in the sagittal plane of the animal’s body, about 
midway between the muscle band of the upper lip and the first 
body band. Intestinal tract making a compact ‘‘nucleus,’’ cor- 
responding to the interval between the eighth and ninth muscle 
bands, and projecting somewhat on ventral side; the broad short 
end of the rectum projecting dorsad from the nucleus to open 
into the cloaca. Dark red generally, though not universally. 
Heart on ventral side, immediately in front of intestinal mass. 
Chain of buds extending forward along ventral median line from 
near the nucleus for a variable distance, then bending on itself 
and reaching back to emerge to the outside through an orifice 
behind the nucleus. 
(b) Aggregate (sexual) generation——Fig. 13. Body ellipt- 
ical in outline, with processes at each end, short and broad in 
the young, much longer in full grown zooids, where they become 
as long as the body. At the outset these processes are always 
