1910.] FKOM CHRISTMAS ISLAXD 833 



smaller than the tM'o or tliree inch higli specimens descrihed hy 

 I5ale, and even than Miss Thornely's innnature Ceylon examples ; 

 for the larjt^est is under 15 mm, in height. On account of the 

 aljsence of intei'mediate athecat/e internodes from the hydrocaulus, 

 and of the presence of a minute median nematophore, with small 

 and delicate pedunculate sarcotheca, in the an^le behind the 

 hydrotheca, the species can readily be distinguished from the very 

 similar P. co^-mtcojnce Hincks, and P, alternata Nutting. Hart- 

 laub* has described a specimen from Laysan, in which the minute 

 sarcotheca immediately behind the hydrotheca is assuredly al)sent, 

 and which, notwithstanding, he assigns to P. huskii ; but I regard 

 the specific identity of the two foi'ms as doubtful. 



The following observations supplenient Bale's description. The 

 lower portion of the stem consists of a varying number of nodes 

 separated by transvei'se joints, the lower nodes being altogether 

 destitute of appendages, while those nearest the cladate portion 

 of the stem, from which they are separated by an oblique node, 

 bear a series of several sai'cothecse. The hydroclades spring alter- 

 nately from one side or the other of a hydi-otheca. In I'ai'e cases, 

 opposite hydroclades arise from the proximal cladate internode, 

 as in Miss Thornely's specimens. The hydi'oclades I'est on a very 

 insignificant process of the internode, which coincides with the 

 base of the lateral nematojDhore. A strong constriction separates 

 this stem-process from the hydroclade, although these specimens 

 do not show the excessive tendency to deciduousness of pinme 

 which Bale noted. 



At the origin of tlie hydroclades there are generally two very 

 short internodes (although rarely only one is present) without 

 appendages, and with transverse nodes ; and these are succeeded 

 by a longer internode which bears, on its anterior surface, a single 

 pedunculate sarcotheca on a swelling near its proximal end, and is 

 limited by a jiroximal tiansverse node, and by a distal oblique 

 node which separates it fi'om the first thecate internode. In these 

 specimens the hydi'oclade is very distinctly divided, by transverse 

 and oblique joints, into intermediate internodes furnished with a 

 single nematophore, and hydrothecate internodes ; and although 

 Bale describes "a hydrotheca on each, except the first [internode] 

 of each pinna," his figure (pi. x. fig. 3) indicates the presence of 

 ;in obscure horizontal constriction immediately above the hydro- 

 theca. Only very exceptionally does the fusion of an intermediate 

 with the preceding hydrothecate internode occur in these hydro- 

 clades, a phenomenon recorded by Billard in the lower portion of 

 the hydrocaulus of the closely related P. cornucopke'f. 



While emphasizing the fixedness of the median sai'cothece in 

 his original description. Bale later regarded only the sarcotheca 

 beneath the hydrotheca as fixed %. I am inclined to agree with 

 the earlier statement, as the large area of their attachment, and 



* Havtlaub, Zool. Jahrb. Sysh, vol. xiv. inOl, p. 374, pi. xxi. figs. 22, 32, 36. 

 + Hillanl, Exp. Sc. ' Travailleuv ' et ' Talisman,' vol. vii. 19u7, p. 207. 

 X Hale, Trans. Roy. See. Victoria, vol. xxii, 1886, p. 9i. 



