HYDROIDA. BALE. 295- 



Plumularians in which such degeneracy seems probable. 

 These are Plumularia filicaulis, Halicornaria humilis, and 

 another dwarf species of Halicornaria, belonging to the 

 ascidioides-group. In all these instances a colony consists of 

 a number of simple shoots, bearing hydrothecse, with here 

 and there a pinnate shoot. As in these species the rachis 

 bears no hydrothecse the simple shoots cannot, of course, be 

 regarded as stems, but as hydrocladia springing directly from 

 the hydrorhiza, and the species must be looked upon as 

 degenerated forms, of which the Halicornarice at least, which 

 are both parasitic species, show abundant evidence in their 

 irregular and depauperated aspect. 



Of the few species of Plumularia represented in this collec- 

 tion P. campanula, P. buski, and P. zygocladia belong to the 

 section Thecocaulus, and they agree also in possessing the 

 character assigned by Allman to Heteroplon. P. sulcata is 

 also a Thecocaulus, but is quite peculiar in its ramification, as 

 well as in other particulars. P. procumbens belongs to what 

 I have regarded as the typical Plumularice, and agrees with 

 the setacea-group in having intermediate internodes on the 

 hydrocladia. 



P. asymmetrica belongs to a group in which there are no 

 cauline hydrothecse, but which differs considerably from the 

 setacea-type, especially in having the margin of the hydro- 

 theca bilobed. Its allies are P. herlwigi, Stechow, P. habereri, 

 Stechow, and P. alata, Bale. 



PLUMULARIA CAMPANULA, Busk. 



Plumularia campanula, Busk, Voy. ' Rattlesnake," i., 

 1852, p. 401. Id., Bale, Cat. Austr. Hydr. Zooph., 

 1884, p. 124, pi. x., fig. 5; Id., Bale, Proc. Linn. Soc. 

 N.S. Wales, (2), iii., 1888, p. 776, pi. xx., figs. 1-6 ; Id.,. 

 Bale, Trans, and Proc. Roy. Soc. Viet., xxiii., 1887,, 

 p. 94 ; Id., Bale, Proc. Roy. Soc. Viet., (n.s.), vi., 1893, 

 p. 113 ; Id., Bale, Proc. Roy. Soc. Viet., (n.s.), xxvi., 

 1913, p. 133. Id., Marktanner-Turneretscher, Ann. 

 K. K. Hofmus. Wien, v. 1890, p. 255. Id., Farquhar, 

 Trans. N.Z. Inst., xxviii., 1896, p. 466. Id., Billard, 

 C.R. Acad. Sci., cxlvii., 1908, p. 759. 



Plumularia indivisa, Bale, Journ. Micro. Soc. Viet., ii., 1881,. 

 pp. 39, 46, pi. xv., fig 1. 



Plumularia laxa, Allman, Rep. Sci. Results " Challenger " 

 Exped., Zool., vii., Hydroida, pt. I., 1883, p. 19, pi. i.,. 

 figs. 5-6. 



