788 REPOKT— 1892. 



proportion of the species belong to the extreme north and south, while the tropical 

 Ascidian fauna is relatively scanty and the individuals of small size. 



The gigantic Molgulidce (the largest of simple Ascidians), such as Ascopera 

 gigantea, A.pedunculata, and Molgula ffigmitea, are only known from the far 

 south ; the large Boltenias are from the north and the south, while to take an 

 example from nearer home, the small Styelas of our seas are represented on the 

 northern coasts of Europe and Asia, and in the Greenland seas, by large specimens 

 of Styela rustica and S. rnonoceros. 



Then in regard to the abundance of individuals, I know of no records of great 

 hauls from tropical seas, while in the Straits of Magellan the Challenger obtained 

 ahout forty specimens of one large species {Molgula gigantea), and a dozen of 

 another (Ascidia Challenger i), at Kerguelen Island, and large numbers of Amarou- 

 ciuin variahile and other compound Ascidians were also obtained, and last summer, 

 while dredging from Mr. Alfred Holt's yacht Argo, ahout eleven miles north of 

 the North Cape, I brought up a dredge net about 3 feet by 1 foot, and about 

 y feet long, crammed to the mouth with splendid specimens of the two closely 

 allied species Styela rustica and S. rnonoceros ; there must have been many 

 liundreds — perhaps thousands. We only picked out and preserved what seemed a 

 few of the better specimens, the remainder being shovelled overboard, and yet I 

 find that about 300 were kept. These large species must evidently be present ia 

 enormous profusion at the bottom in some places. 



On the whole, then, I consider that this more extended survey of the group 

 points to the same general conclusion which I arrived at from an examination of 

 the Challenger collection — viz., that Ascidians attain their greatest development 

 both in numbers and size in the colder northern and southern seas. 



Although certain genera seem, with our present knowledge, restricted to 

 particular regions, none of the more important families is confined to northern 

 or southern seas or to the tropics. I have lately received from the Austrahan 

 coast members of the Botryllidce, a family not previously recorded from southern 

 Esas. 



The examination lately of two collections of Ascidians from the north of 

 Norway and Finmark, made, the one by Canon Norman and the other by myself, 

 from the Argo, recalled vividly the apparent abundance of Ascidians in these 

 northern waters, and caused me to look into the records bearing on the matter. 



10. Note on Atrial, or Glrcumcloacal, Tentacles in the Tunicata, 

 By Professor W. A. Herdman, F.B.S. 



In the interesting paper (' Bulletin Scientifique,' .Tuly 1892) by Dr. C. Julin, 

 which forms the first part of his ' Les Ascidiens des Cotes du Boulonnais,' I notice 

 it is stated, on page 30, ' L'existence d'une couronne de tentacules circumcloacaux 

 n 'a iamais, a ma connaissance du moins, 6i6 signalee chez aucune espece d'ascidien 

 simple ou compost. ' If it has escaped Julin's attention that I described and 

 figured atrial tentacles in 1882 in a .simple ascidian, and in 1886 in a compound 

 one, then I fear it may have escaped notice altogether, perhaps because, along 

 with some other anatomical observations and some theoretical conclusions and 

 suo-o-esiion?, it is buried in the Challenger reports in a mass of detailed descrip- 

 tions of new species. At any rate, the existence of atrial tentacles is evidently 

 so little known that this brief note upon what I have seen of them may be of 

 interest. 



In the simple ascidian Bathyojwiis mirabilis from the Southern Ocean, at a 

 depth of l,(iOO fathoms, there are two circlets of minute tentacular processes which 

 project from the inner surface of the cloacal wall close to the atrial aperture. 

 These atrial tentacles are all of the same size, and are placed at about their own 

 length apart {see 'Rep. Tun. Ghall. Exp.,' part ], vol. vi. 1882, page 167, and 

 pi. xxiv. tig. 12, at. t.). 



The ascidiozooids of the compound (?) ascidian, Goodsiria placenta, from the 

 Cape of Good Hope, have also atrial tentacles, very much like those of Bathyoncus 



