86 THE VOYAGE OF H.M.S. CHALLENGER. 



Bo? tenia, Savigny. 



Yorticella, Linnaeus, Mant. Plant., p. 552. 1771. In part. 



Ascidia, Miiller, Prod. Zool. Dan. 1776. In part. 



Boltenia, Savigny, M£m. surles Anim. sans Vert., pt. ii. fasc. 1. 1816. 



Body more or less globular, fixed on a long peduncle; apertures lateral, four-lobed. 



Test coriaceous or cartilaginous. 



Branchial Sac longitudinally folded, with six or more folds on each side. Fine 



longitudinal vessels present, forming straight stigmata. 

 Tentacles compound. 



This genus was founded by Savigny, 1 in 1816, for the reception of pedunculated 

 Simple Ascidians with a coriaceous test. At that time it contained the species described 

 long before by Bolten (1770), but not named till the following year by Linnaeus, and a 

 new species Boltenia ovifera, Savigny. 



Other species have been added to the genus since by Agassiz, Stimpson, Heller, and 

 others, and finally two new species have been discovered by the Challenger expedition. 



Boltenia elegans, Herdman (PL VII. figs. 1-5). 



Boltenia elegans, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 80. 



External Appearance.— The, body has a quadrangular ovate shape, and is not 

 flattened laterally ; the anterior and posterior ends are bluntly rounded, and the dorsal 

 and ventral edges are nearly straight ; behind the atrial aperture the dorsal edge sinks 

 in somewhat towards the posterior end. The peduncle is long and thin, wiry, attached 

 to the ventral edge of the anterior end, and turned slightly ventrally. The apertures are 

 conspicuous ; the branchial is at the dorsal edge of the anterior end, directed anteriorly 

 and dorsally; the atrial is on the dorsal edge, two-thirds of the way down, and directed 

 dorsally and posteriorly. 



The surface is smooth and glistening, but marked by a few creases. The colour of 

 the body is white, with a satiny lustre ; of the stalk light yellowish brown. 



Length of body, 5.5 cm. ; breadth of body, 4 cm. Length of stalk, 36 cm. ; thick- 

 ness of stalk, 2 mm. 



The Test is thin but tough. 



TJie Mantle is strong, and the musculature regular. 



The Branchial Sac has nine folds on each side, those next the endostyle being closer 

 than the dorsal ones. The transverse vessels are wide and distant. The internal 

 longitudinal bars are narrow but well marked, and run at right angles to the stigmata, 

 which are transverse, lying between narrow longitudinal bars which connect the transverse 

 vessels. The stigmata are rather long and narrow, there are about fifteen in each mesh. 



1 Mem. sur les Anim. sans Vert., 2 e pt. l e fasc. p. 87. 



