Australian Hydroids. 333 



Sacculina arkxosa, n. sp. 



, 11. gen. -et sp.?, Bale, Proc. Koy. Soc. Vict., 



vi. (N.S.), 1893, p 96, pi. iii., figs. 1, 2. 

 IITibiana ra/nosa, Lamarck, An. s. Vert., ii., 1816, p. 149. 

 Lamouroiix, Hist. Polyp. Cor. Flex., 1816, p. 219. 

 Schweigger, Beobacht. auf. naturli. Keisen, 1819, pi. 

 vi., fig. 56. 



This curious zoophyte, which was described by me in 1893, but 

 not named, is so distinctive in character that there seems to be 

 little doubt as to the propriety of assigning] it to a separate genus, 

 even though it is so imperfectly known that we are entirely 

 ignorant regarding its position. In many respects it agrees with 

 the Tihiaiiax raniosa of Lamarck, an insufficiently described species 

 not known to later observers. 



The hydrocaulus consists of string-like stems, sometimes Avith a 

 few ascending branches, which may be given off in a cluster, eight 

 or nine inches, or perhaps more, in height, monusiphonic and not 

 distinctly jointed; it differs markedly from the ordinary mono- 

 •siphonic stem in the singular irregularity of its form, due to the 

 presence of numerous swellings on all sides from which the p'»lyp- 

 tubes originate, and its strangely bent and contorted state in 

 parts, especially near the summit. Its perisarc has a cartilaginous 

 :appearance, is of tough consistence, between*dirty whitish and light 

 brown in colour, and in the older portions very thick but not 

 opaque; the surface showing innumerable markings such as irre- 

 gular striations and wrinklings, with round spots somewhat 

 resembling oil-globules. 



The polyp-tubes are very narrow in proportion to the diameter 



-of the hydrocaulus, springing from all sides and without regular 



order; those on the older portions of the palypaiy are mostly 



•directed upwards from the stem-protuberances, from which they are 



not separated by any partition or constriction ; while in the distal 



i-egion, where there is the greatest irregularity of the stem, they 



are often more distinctly defined and more variable in their 



<lirection. In many of the older ones the central channel 



is not more than one-third of their total diameter. Some 



•of these little tulles are short, their length about equalling 



their width, but more commonly they aie two or three times 



as long. Close to the end they have an annular thickening, 



'darker in colour than any other part of the perisarc, outside which 



the margin is quite sharp, often slightly ragged. Regenerations 



3a 



