194 Soitthern Cross. 



slightly longer than the l)ranchial sac (thorax), while the post- 

 abdomen may be twice as long as the rest of the body, bringing the 

 whole up to about 20 mm. (figs. 2 and 3). At its posterior end the 

 post-abdomen spreads out a little. It is then a plain ectodermal tube. 



Tlu Dorsal Tubercle has a plain circular opening. Figure 4 

 shows its relations to the nerve ganglia and the peripharyngeal 

 bands. 



Tentacles about 12, simple, all the same size. 



The Stomach has longitudinal ridges (figs. 2 and 3). The 

 intestine is large, and rather irregularly dilated. 



This colony was obtained off Cape Adare on January 2nd, 1900, 

 from a depth of 20-24 fathoms, where the temperature of the water 

 was 29° Fahr. It is preserved in formol. In the bottle along with 

 it is a large mass of the gelatinous spawn of some mollusc. The 

 appearance of the animal suggests the genus Diazona, which, 

 however, has internal longitudinal bars. 



It seems best to put this new species in the genus Tylohranchion , 

 established in the ' Challenger' Eeport for a species {T. speciosum) of 

 which three colonies were obtained at Kerguelen Island from depths 

 between 10 and 100 fathoms. Ti/lohranchio7i &peeiosiim, while 

 agreeing in general anatomy with the present species, differs from it 

 in form of colony (see ' Challenger ' Eep., Part II. PI. XXII, fig. 1) 

 and proportions of ascidiozooid, and in details of most organs. It 

 shows, however, the same bifid papillae on the transverse vessels of 

 the branchial sac. 



Atopogaster elongata. (Plate XXI., figs. 1-10.) 



(See ' Challenger ' Rep., Pt. II., p. 173, 1886.) 



This is a species that was trawled up in quantity during the 

 ' Challenger' expedition at Station 313 in the Strait of Magellan, from 

 55 fathoms. The ' Challenger' colonies presented a great variety in 

 form, and the specimens now before us do so to an even greater 

 degree. On plate III. we show a few prevalent shapes selected from 

 the hundred or so in the collection. 



The greater number of the specimens, over fifty, were obtained 

 washed up on the beach at Cape Adare on April 6th, 1899. A 

 handful of the smaller ones (figs. 6 and 7) look like nothing so much 

 as a group of new potatoes. The larger colonies (figs. 1, 2, 4, 

 and 8) are more irregular in form. 



Other specimens were obtained : — 



"April 24th," one specimen. 



