154 THE VOYAGE OF H.M.S. CHALLENGER 



sac are elongated vertically, and contain about three to five stigmata each. The 

 transverse vessels are of three sizes placed alternately. The stigmata are long and 

 narrow, and are placed with regularity. 



Tlie Endostyle is wide and consiMcuous. Its course is undulating. 



Tlie Dorsal Lamina is a plain membrane with a very irregular margin, and with a 

 series of indistinct transverse ribs. 



The Tentacles are very numerous. They are of two sizes placed alternately. The 

 larger are very long and are closely placed. 



Zoca%.— March 3, 1874; Station 157; lat. 53° 55' 0" S., long. 108° 35' 0" E. ; 

 depth, 1950 fathoms; bottom. Diatom ooze; surf temp. 37°'2 ; bottom temp. 32°'l. 



This species resembles a silkworm's cocoon in its external appearance. The shape 

 is fairly regular and symmetrical (PI. XL fig. 14), and the surface is covered by a 

 close investment of silky hairs. The longest of these are found near the anterior and 

 posterior ends of the body, where they project 5 or 6 mm. from the surface of the 

 test. Some of them, however, are very short. These hair-like processes are usually 

 simple, but some of them branch occasionally. They are seen wdien highly 

 magnified to be finely roughened all over their surfaces. Sand grains. Diatoms and 

 fragments of Foraminifera and Radiolarian tests are attached to them here and there. 



The apei'tures are cross-slit, and have slightly raised margins where no hairs are 

 present (PI. XL fig. 14). The mantle has a number of brownish pigment cells scattered 

 through it. 



The folds of the branchial sac are exactly like those of Styela ohlonga ^ and some 

 other species of the genus. The stigmata vary in length, as in some cases they are 

 not interrupted by the third or smallest order of transverse vessels (PI. XL fig. 15). 

 The internal longitudinal bars are wide and ribbon-like, and they are rather irregular 

 in their course. 



The condition of the tentacles is very characteristic. The two orders are very 

 difi"erent in size (PL XL fig. 16), the smaller ones being very short and dark-coloured; 

 while the larger ones are of great size, and are membranous and light-coloured. 



The alimentary canal is relatively small. It lies at the posterior end of the body, on 

 the left side of the branchial sac. The stomach has its walls thrown into closely-placed 

 longitudinal folds. The ovaries are two in number, one on each side of the body. 

 They lie in the posterior half, and run obliquely forwards and ventrally. Their anterior 

 ends nearly touch the sides of the endostyle. 



This species belongs to the same section of the genus as Styela ohlonga, but difi'ers 

 notably from that and all other species of Styela in the peculiar condition of the test 

 and in the arranoement of the tentacles. 



1 Sec this Report, Part I., p. 160. 



