THK SKKTI'LAKID-K. 75 



PASYTHEA QUADRIDENTATA (Ellis and Solanderi. 

 (Plate XIII. li-s. t 7 



.s'c/Vii/nri'i ijiindi'iili'iiliilti Ki, I. is uml Siii.AxiiKi!, Nat. Hi.-t. Xoupli.. 17sr>, p. ">7. 

 SBrtufario tjiifidrK/nttnlii (|MI-:I.I\, Svstrma Nalur;i- i Linna-nsi, I7SS. p. :;s.">;;. 



l'<iKiiilii-ii i/iiiidi-idi'iiiiiin Ksi'KK, Die Pflanzenthiere in Abbildungen, 111, I7ss. p. LM7. 

 Si'rtidiiriti 1/iitidriili'iiiittn Ksi'Kii, Fortsetzungen <ler Pflanzenthieren, II. 17'.M, p. .'12. 



Si rlidiii-in ijiindridi iiliiln Ilcisc, Mist. nat. lies Vt-rs, III, 1SO2, p. !I7. 



1'iixiiilii'ti (K'l'/ii/ni-iii) i/iHidi-idi'iiiiiiii I.AMi>ri:i>i\\, Bulletin philomatique, lsi2, p. is:;. 

 Paiylhea -quadridentata I.AMnrnorx. Hist, dee Polypiers coralligenes, isiii. p. i.'iii. 

 Sertularia quadridentata LAMAKC-K. Hist. nat. aiiiin. s'ans vert., II, isiii, p. 121. 



i/iiii/lridi-iiliilii SfiiwEKicKK, Handlmch <lcr Natnrjicschirlitc, ISL'll, p. 4'Jli. 



iiiin/lriili'iiliilii LAMDI-HOI-X, l^xpusitinn nii'thi)dii|Ui', 1S21, p. !i. 

 Tn/ijHiriti i/iiiidriili'iilnlii <\<- Iii.Aixvn.LE, Maniu 1 ! il'Artiniilnjjie, ls:!4-ls."7. 

 Pagythea quadridentata !' M.K, Australian Ilydmiil Xunph.. Iss4, p. 11-. 

 J'uxi/llii'ii <iii<idcid,-iitnl<i vim I.KXIH:.M-EI.]I, Vnstralian HyilriiiiiciliisM-. 1SS4, pp. 41!i, (i24. 

 J'lisi/llii'u quadridentata BALI:, ['me. I. inn. Sue. New Smith Wak's, LM scr. , III, Isss. ].. 770. 



ijiiiidridi'iilnln .Ar.MiKT.vxxKii-TriiXKKET.sc iiKit, Ilyilniiilcn ill's k. k. naturliist. I Iiifiini.Tiinis. Is; in, p. 2:54. 



i/iiiidi-idi'iittita Tiim:\i:i,v, Ilyilmiil yCmiph\ ti-.- ni'ilfrU-d l>y I>..rtnf \Villcy. Isil'.i, p. 4"i(i. 



iiiin . Colony attaining a hciy'lit of uliotit one-third of :ui im.-li. i-on>i>tinu' of a single 

 anbranched stein o-rowin^ from a crecpinjf root-stalk, dividcil liy obiiijuc node-: into regular 

 internodes, each of which hears a pair of hydrotlieca-, or two or three pairs in a closely 

 ((impressed yroup. Hydrotlieca 1 on the iirst internode a sinylc opposite pair, contingent for 

 about half their height in front, somewhat swollen below, the distal part curving to a narrow, 

 bidentate. or obscurely tridentate mai-yin. and an operculum of two llaps. Soinetimes the Iirst 

 intornode bears two pairs of opposite hydrothecie, the lower of which is like the pair just 

 do-scribed, the other pair lieiii^' wedded in between the diveryin.L;' free jiortions of the lower 

 hydrotheca', the bases of the former beiny indented by the latter. Sometimes two or more 

 intornodes have this same arrangement of hydrotheca 1 . One or more of the distal internodes 

 ol'leii have a -roup of three pairs of hydrotheca'. the lower two boinjf as just descrilied. the upper 

 beiny wedded in between the second pair, so that they are widely separated, the upper pair hein^ 

 more erect, more extensively adnate to each othei- than the others: lowest pair largest, next 

 smaller, and the upper pair smallest. 



(roniwmie. A single ,'onan<, r iiiin is borne at the base of the stem, ovate in shape, with annular 

 corrugations, a very broad, round aperture, no collar, and an operculum stretched across like a 

 drumhead. 



Distribution. Coast ot Africa, near the island of Ascension ( Kills and Solander): Kitxroy 

 Island and Point Stevens, Australia (Has well); Coogee, Iiondi, Australia (Bale); Atlantic Ocean 

 (Marktanner-Turneretscher); South Seas (Thornely); between Eleutheraand Little Cat Island--. 

 British West Indies (Bahama Kxpedition. State I'liiversity of Iowa). 



This species seems to be alwavs found growing on floating seaweed. 



SERTULARELLA Gray (modified). 



Truji/iiiK'iiin . Ilvdrotheca 1 hi.serial. strictly alternate, usiuillv with three or four marginal 

 teeth and a well-marked operculum with three or four flaps-. Rarely the teeth are obliterated, in 

 which case the operculum is stretched across the hydrothocal aperture like a drumhead. 

 Branches never regularly anastomosing to form a reticulate, llabellate structure. 



(loiinxoiH, . (ionanu'ia usually ornamented with annular corrugations or ridges. Aperture at 

 the end of a trumpet -shaped tube, or else encircled by a narrow, broad collar, and several biunt. 

 spine-like projections. 



This is perhaps the most .satisfactory generic group of the Sertularida 1 . because it is capable 

 of more exact delimitation than the other genera, and is based on characters that are easily seen. 

 As originally defined hv (irav. 1 the evims contained but two species, \. polyzo^ios and .s'. /v/ 



1 List of Specimens of British Animals. Kailiata. Liimlmi, 1S47, \>. (58. 



