$3.] 0VERSIGT OVER NORGES ASCIDIAE SIMPLICES. 



93 



The mouth orifice, at the point of the unusually long 

 outh-siphon; this is almost equally thin over its whole length, 

 ough somewhat thicker before the middle, turned somewhat 

 -er towards the right, and slightly bent. 10 red o-cells. 

 ne sewer siphon is situated behind the middle of the body. 

 id turned strongly over on the right side; about 6 o-cells. 



The muscle as usual about only developed on the right 

 Be; the long mouth-siphon has fine, inner, longitudinal 

 :iiscles, and in a spread form, but powerful ring muscles, 

 lich do not run quite parallel, but cross each other at various 

 Igles. 



Numerous, very closely situated, long and short tentacles ; 

 ng zone broad, closely furnished with fine processes. 



The ring furrow runs parallel with the tentacle ring, and 

 : finely curved. 



The dorsal tubercle small, without rolled in horns, the 

 (ening between these turns in front; in the beginning of 

 Is dorsal fold as a continuation of the ring furrow, upon the 

 ] ? t side, there is a long and distinct „goutiére dorsale" with 

 Ty broad edges (fig. 8). The nerve-ganglie is situated rather 

 I: behind the dorsal tubercle, viz. 2 mm. from it. 



The dorsal fold is ribbed on the left side, the edge 

 s ongly dentated; to each bar answers one high tooth, and be- 

 i een two such there generally comes two small. The dorsal 

 id runs a little beyond the swallow. 



The endostyle very broad, the outer walls strongly cre- 

 i lated. The branchial sack goes a little behind the intestinal 

 (nal. The transverse arteries of 2 sizes. The internal longi- 

 tlinal bars thin, with large, conical papillæ on the crossing 

 ]ints of the transverse arteries. The intermediary papillæ 

 £5 not, they seem to appear in certain places but closer 

 (amination proves that they cannot be considered as inter- 

 i diary, as at these places the transverse arteries of the 

 S l order have disappeared, and consequently these papillæ 

 fswer to those that are situated on the crossing points 

 ( the internal longitudinal bars and the transverse ar- 



4 



