376 APPENDIX. 



Ttis species is placed doubtfully in the Rattlesnake Col- 

 lection. It occurSj however, in Van Diemen's Land and 

 New Zealand (Dr. Hooker), and is abundant in South 

 Africa. 



Fam. 4. CABEREAD^. 



Polyzoarium entirely divided into ligulate dichotomous 

 hi or multiserial branches ; back nearly covered by large 

 vibracula ; avicularia sessile. 



16. Caberea, Lamouronx. 



Selbia, Gray. op. c. Vol. II. p. 292. 



Cells bi-multiserial, in the latter case quincuncial. 

 Posterior surface of branches concealed by large vibracula, 

 which are placed obliquely in a double row, diverging 

 in an upward direction from the middle line, where the 

 vibracula of either row decussate with those of the other. 

 Avicularia when present of the flexible kind, sessile on the 

 front of the cell. 



The remarkable feature of this genus resides in the vibra- 

 cula, which here appear to attain their utmost develop- 

 ment. Each vibraculum appears to belong not to a single 

 ceU as in Scrupocellaria, but to be common to, or appHed 

 to the backs of several. They are more or less pyriform 

 or long oval in shape, and the two rows decussate with each 

 other along the middle of the branch — giving in the 

 narrower species, especially, much the aspect of an ear of 

 barley, and in the wider of a straw plait. The walls of the 

 vibracula are usually thin, and very transparent, so as to 

 allow the outlines of the cells to be seen imperfectly through 

 them. The upper and outer extremity of the vibraculum 

 is bifid, and to the inner horn is articulated the seta, and 

 from the notch between the two horns there is continued 

 nearly, if not quite, to the inner extremity of the organ, 

 and along its upper border, a shallow groove, in which is 



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