346 



If. M. Bale : 



There is a certain similarity between this species and the P^ 

 conspecta^ of Billard; in the latter, however, there are no inter- 

 mediate internodea on the pinnae, but every internode (except the- 

 first) supports a hydrotheca, there is no intrathecal ridge, and the- 

 arrangement of the sarcothecae is different. 



P. halti Billard, is a different species, also of the Hcdopterisr 

 type. It is now referred to the genus Antennella, 



Plumulauia coRKUGATissiMA M. and T. (Plate XVll., J^'ig. 3). 



Plumularia setaceoides, var. corrugata, Mulder and Trebil- 



cock, Geel. Nat. (2), iv., 1911, p, 118, pi. ii., fig. 8. 

 Plumularia corrugata, Mulder and Trebilcock, Geel, Nat.- 



(2), vi., 1914, p. 43, pi. v., fig. 3. 

 Plumularia corrugaUssima, Mulder and Trebilcock, GeeU- 



Nat. (2), vi., 1915, p. 53. 

 Net Plumuhiria corrugata, Nutting, Amer. Plum., 1900,. 

 p. 64, pi. vi., figs. 1-3. 

 Hydrocaulus monosiphonic, pinnate, about 12 mm. in height, 

 stem divided by oblique joints into short internodes, each support- 

 ing a hydrocladium but no hydrothecae; hydrocladia alternate, 

 borne about the middle of the stem-internodes, the first internode- 

 short, witliout appendages, the others alternately long and short, 

 only the former bearing hydrothecae. 



Hydrothecae very small, cup-shaped, with the front contracted 

 below the everted lip ; aperture entire, somewhat oblique, back 

 adnate as far as the margin. 



Sarcothecae bithalamic, canaliculate, one below each hydrotheca 

 and two lateral above, one midway between every two hydrothecae,. 

 on the intermediate internode, two in each axil, and one just above 

 the base of each pinna, all rather thin-stemmed and apparently 

 moveable. 



Gonosome ? ^ 



Loc. — Torquay, Barwon Heads, Spring Creek, (M. and T.). 

 A small form not closely related to any of our known species^ 

 The hydrothecae differ from those of P. setaceoides in not being- 

 free at the back, and rather resemble those of P. scahra, but it is- 

 doubtful to what extent the contraction below tlie lip exists in life, 

 as the specimen shoAvs apparent sign of shrinkage at that part. The- 

 strong development of the internal ridges of the perisarc gives to^ 

 the species a very characteristic corrugated appearance. 



1 Arch, de Zool. exp. et gin. (4), vii., 1907, \>. 362, fig. xi. 



