The Tunicata of the Scottish National Antarctic Expedition. By W. A. Herdman, 

 D.Sc., F.R.S., Professor of Zoology in th<> I'nivrrsity of Liverpool. (With 

 One Plate.) 



(MS. receivcil January *, 1912. Read February 19, lilli'. ISSIILM! s.-jai-n.-ly July 3, 1912.) 



So far as regards number of individuals, .-mil their size, this is one of the largest 

 collections of Ascidians brought back in recent years from Antarctic seas. It contains 

 almost exactly the same number of species of Ascim.v K.\ (. lx.W/,r Sim/i/ice$ + Asci</i:r 

 Composite) as the Discovery collection viz. fifteen or sixteen but whereas in the 

 latter collection nearly all the species were represented by single specimens, in the 

 Scotia collection most species can show long series of individuals in all there are about 

 two hundred specimens, as against the thirty-three brought home by the Discovery. 



The sixteen species in the present collection represent almost as many genera, and 

 half a dozen families. The systematic arrangement is as follows : 



ASCIDIACEA. 



Family MOLGULID^E. 



Paramolgula gregaria (Lesson). 

 Paramolgula horrida (Herdman). 



Family CYNTHIIIXE. 



Boltenia leyumen, Lesson. 

 /''uiH/idns antarcticus, n. sp. 

 Halocynthia setosa, Skater. 



Family STYKLIU.K. 

 Sfi/efo /often, Herdman. 

 Stycla paessleri, Michaelsen. 

 Synstyela /IKTHSIOIIH, Herdman. 



I'it/t/:no 



tio. Lesson. 



. Herdman. 



Family ASCIDIJD.K. 

 Asci'lto f/ioi-i //'. Sluiter. 



Family DISTOMH* i 



< ',,/,'//n pedunculate ('>'. and ( ;.). 

 Ilnl, i-_oo <////'/,<///((/, Lesson. 



Family POLYCUNIIM:. 



Polyclinum complanatum, 

 Amaroucium <list<>,>n>iil<'s, Herdman. 



It is interesting to notice how greatly some of these recent collections from the far 

 South differ from one another in the species represented. The following table- which 

 gives only the sixteen species in the Scotia collection shows that only one form 

 (Halocynthia nctosa) from that collection was also taken by the Discovery, whereas ten 

 species were taken by the Challenger, eighi by the Hamburg .Magcllani.- and Smiih 

 Georgia Expedition,' and five by the French Antarctic Expedition under Charcot. This 

 can be explained to some extent, at least, by the precise localities visited : 1 lie XW/, the 

 ('/nillfin/iT, and the Hamburg collections were larg.-ly made in the Magellan and Falk- 

 lands neighbourhood, while the other three collections were mainly from farther south. 



(KEI'IUNTKLl FRu.M Till: Tli A \s M TK '\s dl' TIIK HCIYAI. SUCIIIIV ol l.hlXBi IKill, MM,. XI, Mil., IM'. HO") :i^0.) 



