134 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



them through vascular processes arising from the posterior end of 

 the abdomen and joining the common stolons. The smaller specimen 

 is a looser group of a few zooids connected by stolons. 



The largest zooids are in the preserved condition about 23 mm. 

 long. Each consists of a long, very narrow abdomen inclosed in a 

 tubular sheath of tough test which extends posteriorly into a more 

 or less elongate pedicel and at the anterior end enlarges (expanding 

 more toward the ventral than toward the dorsal side) into a rounded 

 or oval mass inclosing the thorax. The thorax is short, wide in a 

 dorso-ventral direction, and narrow from side 

 to side. Branchial aperture slightly lobed or 

 almost plain, atrial aperture larger, and plain 

 edged. Neither is greatly produced. The abdo- 

 men joins the thorax at the extreme posterior 

 dorsal part of the latter, and an abrupt bend in 

 the proximal part of the abdomen is generally 

 present, so that the main axis of the thorax as- 

 sumes a direction nearly at right angles to the 

 long axis of the abdomen and pedicel. 



Mantle thin; about the apertures there are 

 slender circular fibers, but no strong sphincters. 

 On each side of the thorax about 15 narrow 

 widely separated muscle bands extend poste- 

 riorly from the region about and between the 

 apertures, each being generally formed by the 

 union of two or more slender bands. Trans- 

 verse muscles are but little developed, though a 

 few slender circular bands cross the longitudinal 

 ones on the anterior part of the thorax. 



Tentacles 16 ; 8 large and 8 smaller ones alter- 

 nating. 



Dorsal tubercle prominent ; cup-shaped with a 

 rounded orifice. 



Dorsal lamina replaced by a series of large 

 triangular languets borne transversely upon the 

 wide median dorsal vessel. They are continuous 

 at their lateral angles with broad membranes borne along the whole 

 length of the transverse vessels of the sac. 



Stigmata long and narrow, separated by very slender interstig- 

 matic vessels. Number of rows apparently 6, with about 40 in a row 

 on each side. 



Intestinal loop very long. Stomach long and narrow, not notice- 

 ably wider than some parts of the intestine. Apparently it is smooth 

 walled. 



Fig. 88. — Clavelina de- 

 torta (s l u i te k). 

 Left side of body 

 of zooid. x 4. 



