818 ME. J. RITCHIE OX HYDEOIDS .[May 24, 



by its dwarfish size — the diametei- of tlie stem is only I, tlie length 

 of the hydrothecje less than i, their diametei- 1 those of 

 typical Australian specimens (cf. table of dimensions given above). 

 Var. p-iisilla is also to be distinguished by the slightly more 

 flaring margin of its .hydrothecEe, and by its hyaline perisarc, for 

 that of the robust typical variety is tinged with brown. It is 

 possible that the discovery of their gonosomes may separate those 

 two forms specifically. 



Professor C. Hartlaub, in his fine monograph of the genus 

 Sertidarella (1900, p. 65), regards S. cylindrica, somewhat doubt- 

 fully, as a synonym of *S'. Integra Allman, described from New 

 Zealand specimens. The delicate texture of the h3-drotheca3 is so 

 different, however, from that of the type of SertulareUa which 

 bears intrathecal marginal teeth, that, apart from other obvious 

 diflerences of form, sculpture, and proportion, I regard the 

 presence of intrathecal teeth in Allman's species as suflicient, 

 in this case, to indicate specific diii'erence. 



Sertulakella poltzoxias Linnfeus, 1758. 

 Yar. CORNUTA Ritchie (?), 1909 b. 



A single fragmentary colony, 34 mm. high, represents this 

 species. The hydrothecre agi-ee in structure with tj-pical sjieci- 

 mens, but a single internode occasionally bears more than one 

 hydrotheca. The habit of the colony, too, is much more definite 

 than that of the lax variety {(/racilis) of British seas, for from a 

 deiinite, thick stem spring alternate branches almost at right 

 angles. In this respect the specimen approaches var. robusta 

 Kirchenpauer (1884, p. 38), from Cape of Good Hope, and var. 

 cornuta, from the neighbourhood of the Andaman Islands. The 

 absence of the gonosome precludes certain decision as to which 

 variety it belongs, but the trophosome agrees in detail with that 

 of var. cornuta. 

 Dimensions : — 



Stem, diameter 0"63-0'70 mm. 



Hydrotheca, length oi adnate portion . 0'32-0-45 mm. 

 „ „ free „ 0'28-0-39 mm. 



„ greatest diameter 0-24-0*25 mm. 



„ diameter at mouth O-lT-O'lS mm. 



Locality. St. 23, Five Islands, 8 to 12 fathoms, rock and sand, 

 and mud ; rare. 



Sertulaeella QUADHIDEK.S Bale, 1884. (Plate LXXVII. 

 figs. 12 a, 12 b.) 



The transverse chitinous projections from the bases of the 

 hydrothecse are mostly absent, and where they do occur are much 

 less distinctly marked than in Bale's figure (pi. vii. fig. 5) of a 

 Holborn Island specimen. The hydrothec-e are strictly alternate, 

 but the internodes are very irregular in length, from eleven 

 to thirty-six bydrothecje occurring between successive nodes. 

 [20] 



