KEPORT ON THE TUNICATA. 83 



cells (PI. VIII. fig. 8) through the stages shown in figs. 9 and 10, in which there are 

 many nuclei in the fibre, but the cross striation is not yet present, and it has not 

 broken up into fibrils, up to the completely difierentiated tissue shown in figs. 11 and 12. 



The nervous system and the dorsal tubercle are particularly well preserved, and are 

 clearly visible in the specimen which is now mounted as a microscopic object (see PI. 

 VIII. figs. 14 and 15). There is a triangular peritubcrcular area in which the closely 

 placed nerve ganglion and dorsal tubercle (PI. VIII. fig. 14) are situated. This is a 

 point in which the present species difi'ers from Salpa democratica-mucronata, where 

 the dorsal tubercle is considerably in front of the nerve ganglion. 



The ganglion is of rounded form, with a large club-shaped sense organ (ocular) near 

 its anterior end, and with a pair of laterally placed wing-Hke appendages (PI. VIII. 

 fig. 15, ap.). There are at least si.xteen or eighteen distributory nerves given off from 

 the ganglion, and they arise from its sides as well as from the ends. Four of the nerves, 

 running two anteriorly and two posteriorly, are large, the rest are nearly all very small. 

 On one of the smaller nerves springing from one side of the ganglion a small rounded 

 granular mass is placed ; this is possibly another sense organ (PL VIII. fig. 15, s.o.). 



The large club - shaped sense organ attached near the anterior end of the 

 ganglion (PI. VIII. fig. 15, op.) is probably an organ of sight. It has a clear, trans- 

 parent, concavo-convex disc on its free end, and behind that is a layer of somewhat 

 ovate columnar cells, darkly pigmented of a reddish colour, which probably forms the 

 retina. The short stalk is mainly cellular, and where it joins the ganghon there is 

 another band of dark reddish pigmented cells (PI. VIII. fig. 15). 



The dorsal tubercle is very large, but has a simple structure. Its posterior end is 

 embedded in the front of the ganglion. The edges of the elongated elliptical slit are 

 formed of regularly placed columnar cells richly ciliated. The rest of the surface of 

 the tubercle is also ciliated, which gives it a finely striated appearance (PI. VIII. fig. 15). 



There are three very young embryos (or ova) situated on the left side of the body, 

 behind the endostyle, and between the sixth and seventh muscle bands. This specimen 

 is therefore an a2;2;recratcd or sexual form. 



Salpa africana-Tnaxima, Forskahl. 



Salpa maxima, Forsk., Descrip. anim., p. 112, 1775. 



Salpa africana, Forsk., Descrip. anim., p. IIC, 1775. 



Salpa africana- iiMxima, Krobn, Ann. d. Sci. Nat., (Zool.), scr. .3, torn. vi. p. 112, 1S4G. 



Salpa africanormaxima, Traustedt, loc. cii., p. 374, which see for further synonymy. 



A single large Salpa obtained in the Southern Ocean is probably referable to the 

 solitary form of this species. The locality is March 10, 1874, Station 159 ; lat. 47° 

 25' 0" S., long. 130° 22' 0" E. ; surf temp. 51°-5. 



