EEPORT ON THE TUNIGATA OF PLYMOUTH. 51 



Body oblong, more or less clavate, not provided with a post- 

 abdominal peduncle. 



Stolons distinct, delicate and branched. 



Professor Herdraan has quite recently* subdivided this genus as 

 it was defined in his " Challenger " Eeport. The difference recog- 

 nised by Savigny between the types borealis and lepadiformis, in 

 regard to the presence or absence of a well-developed post-abdominal 

 peduncle of test-substance, is raised by him into a criterion of generic 

 value [PodoclaveUa) , while the rudimentary "common test '^ enclosing 

 the stolons of the " Challenger " species constitutes the salient 

 character of his new genus 8tereoclavella. These changes have been 

 rendered desirable by an increase in the number of species and the 

 apparentf distinctness of the three types. As the table in Pro- 

 fessor Herdman's paper shows, the restricted genus now includes the 

 species lepadiformis (0. F. Miiller), rissoana (M. Edwards ; variety 

 only ?), pumilio (M. Edw.), producta (M. Edw.), Savigniana (M. 

 Edw.), and nana (Lahille). 



Is not Miiller's Ascidia gelatina (Zool. Dan., iv, 26, plate 143) 

 also probably a species of Clavelina ? 



1. Clavelina lepadiformis, 0. F. Miiller. (PI. II, fig. 1.) 



Ascidia lepadiformis, 0. F. Miiller. L. c, p. 54, pi. Ixxix, fig. 5. 



— — Bruguiere. L. c, pp. 142, 151, 152; pi. Ixiii, fig. 10. 



— — Turton. L. c, p. 95. 



Clavelina lepadiformis, Savigny. Tableau systematique, p. 174. 



— — Fleming. L. c, p. 202, pi. xvi, fig. 57. 



— — Milne-Fdwards. L. c, p. 267, pi. i, fig. i ; ii, fig. 1. 



— RISSOANA, Milne- Edioards. L. c, p. 267. 



— LEPADIFORMIS, Thompson. Rep. ou Fauna of Ireland, Rep. Brit. 



Ass., 1843, p. 264, 

 Clavellina — Alder. L. c, p. 108. 



Clavelika — Forbes and Ranley. L. c, p. 26, pi. E, fig. 1. 



— — DicMe. Rep. ou the Mar. Zoology of Straugford 



Lough, Brit. Ass. Rep., 1857, pp. 105, 111. 



— — Mennell. Rep. of Dredging Expedition to Dogger 



Bank and Coasts of Northumberland, Trans. 

 Tyneside Nat. Field Club, 1862, p. 12. 



— — A. M. Norman. Last Rep. on Dredging among 



Shetland Isles, Rep. Brit. Assoc, 1868, p. 303. 



— — Oiard. Recherches, 1. c, pp. 613 — 615, pi. xxi, 



figs. 2, 5; xxiii, fig. 2. 



* On the Genus Ecteinascidia, &c., loc. cit. 



t One of the individuals in Milne-Edwards' figure of Clavelina producta (1. c., pi. ii, 

 fig. 3) exhibits a post-abdominal peduncle of some extent. 



