194 Soutlicni Cross, 



slii,'htlv loni^'or than the Itraiichial sac (thorax), while the post- 

 ahtl<»nien may he twice as long *as the rest of the hody, bringinji the 

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

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



The Dorsal Tuhcrcle has a plain circular opening. Figure 4 

 shows its relations to the nerve ganglia and the peripharyngeal 

 JLiauds. 



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 

 aijpearanee of the animal suggests the genus Diazona, which, 

 however, has internal longitudinal bars. 



It seems best to put this new species in the genus Ti/lobranchion , 

 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/lohranchion speciosum, while 

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

 in form of colony (see ' Challenger'' l{ep., 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., fiizs. 1-10.) 



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



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

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

 ftf) 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 Gth, 1899. A 

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

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

 and 8) are more irregular in form. 



Other specimens were obtained : — 



"April 24th." (nio specimen. 



