98 



BRITISH TUNK'ATA. 



at the surface of a crimson colour; much enlarged 

 and widely fusiform. Mantle rather delicate, with 

 the apertures tubular, well produced. Tentacular 

 filaments slender, distant, not numerous. Brandt ia I 

 sac narrower than the visceral mass, with papilla? at 

 the intersections of the meshes and smaller ones on 

 the bars between them, all having on each side a 

 tubercular swelling. Oral lamina transversely ribbed 

 and pectinated. 



Length upwards of two inches. 



Halt. Between tide-marks. 



2S -f 



FIG. 20. Ascidia Alderi. Natural size. 



CHANNEL ISLANDS. Herm, Guernsey (Norman). 

 First record. Hancock, 1870; coll. Norman [1865]. 



We have had the opportunity of examining but one 

 individual of this species, and as it had been for some 

 time in spirit little can be said respecting its colour. 

 All the other characters however were determinable ; 

 and they are sufficient to distinguish it from all known 

 species. 



The test (fig. 20) was a little affected with parasitic 

 zoophytes; but the greater part of the surface w;is 

 quite free, and exhibited with great distinctness the 

 short, thick, deep crimson-coloured extremities of the 

 blood-channels, which are very numerous and much 

 subdivided ; the terminal twigs are considerably en- 

 larged and are pretty-regularly fusiform with the 

 extremity mucronated. The larger branches are gener- 

 ally of a pale yellowish red. 



