$3.] 0VERSIGT OVER NORGES ASCIDIAE SIMPLICES. 



101 



he folds converge towards the bottom of the branchial sack, 

 >t towards the swallow, they stop a little before they reach 

 e fine dorsal fold, and hereby, between the swallow, and 

 e begi nning of the hypobranchial furrow, there arises a 

 iooth, leafshaped split mesh, over which the fine dorsal fold 

 .ns from the swallow to the hypobranchial furrow. Directly 

 ider this mesh lies the stomach with its gland organs (fig. 34). 

 etween the folds 4 — 5 internal, longitudinal bars ; transverse 

 teries of 4 different sizes, of which those of the 4 th and 

 'ten those of the 3 rd order go over the spiracles without 

 terrupting them. 4 — 6 very rectanguler spiracles in each 

 esh. As will be seen by fig. 4, which represents a piece of 

 le branchial sack, between 2 folds, and 2 transverse arteries 

 the l st order, the spiracles that lie nearest the folds arrange 

 emselves in arches, on each side of the fold. The swallow, 

 mnded on the left side by the dorsal fold, on the right, by 

 slight, rather curved lip. The esophagus is short, and 

 trrow; the stomach, by degrees, goes over into the gut, and 

 \s a glandular appendage upon each side. The gut forms a 

 rge, closed, twist, its hindmost part tucking itself into the 

 ophagus, and then rising a little into the sewer space (fig. 32). 

 le anus is 2 lipped, the edge not bent down, finely lipped. 

 large, elongated, very slightly lipped, genital gland on each 

 le; the left lies over the gut, and penetrates into the gut 

 dst. A distinct, export canal that opens into the sewer 

 ace (fig. 32). 



Molgula siphonalis, M Sars, 1858. 

 (Fig. 37—40). 



The body unattached almost globular, but longer than 

 l'»h or broad. Length : 24 mm. Breadth: 15 mm. The testa 

 1 hyaline, thin and brittle, and furnished with a long, close 

 tit of fine fastening thread, to which is attached fine sand 

 tas (fig. 37). The mouth orifice is situated before the ani- 

 i il's middle axis. The sewer opening is about in the middle 



