Little-hnoivn Victorian Fossils. 107 



Localities and Horizon. — Junction of Woori-Yallock and Yarra 

 Kivers, collected by Geol. Surv. Vict. B. 23 [340-5], and gully 

 near porphyritic dyke west of Mount Disappointment, south of 

 Kilmore, collected by Geol. Surv. Vict. B. 16 [346-8]; specimens 

 in National Museum. Also Kilmore and Manslield district (Sweet 

 •collection, recorded by Dun, loc. sup7-a cit.). Probably from Yass^ 

 .(by W. S. Dun); and Yass district, — Bowning series, — New South 

 Wales (by R. Mitchell)^; Zeehan, Tasmania (R. Etheridge, jun.). 

 ■Silurian. 



Class CRINOIDEA. 



Family % Platycriiiidae^ Roemer. 



Helicocriiuis., gen. nov. 



Generic characters. — The arrangement of the plates in the 

 dorsal cup is monocyclic. Basals, 3; radials, 5; priraibrachs ? 

 (only one preserved in specimen). Tegmen fairly high, vaulted 

 over with numerous polygonal (usually pentagonal) plates. Arms, 

 5, forked once, ? on thix'd brachial plate; pinnules numerous. 

 Stem pentagonal, with alternate columnals transversely ridged, 

 and crenelate. Evidence of small cirri at intervals down the 

 stem. Proximal end of stem coiled (this last-named character is 

 by no means confined to this genus, but it is so conspicuous in 

 our specimen that it is incorporated in the new generic term 

 merely as a distinction). 



Observatiotis. — This type approaches Hapalocrinus, Jaekel,'^ in 

 many respects, but in the latter genus the tegmen is lower, and 

 the stem is round, with longer columnals. 



Helicocrinus differs from the typical platycrinids in the larger 

 number of plates which make up the summit or oral region of the 

 test, and also in the pentagonal form of the stem.'' Its otherwise 

 close relationship with Jaekel's group of the Hapalocrinidae, 

 ■equivalent as Bather has shown^ to Wachsmuth and Springer's 

 interpretation of the Platycrinidae, compels one for the present at 

 least, to leave it in this group. 



1 Proc. R. Soc. Vict., new series, vol. x., pt. ii., 1898, pp. 84, 85. 



2 Proc. Lin. Soc. New South Wales, series 2, vol. ii., 1887, pp. 412, 413. 



» Palaeontologische Abhandl, Jena, vol. vii. (new series, vol. iii.), 1896-7, p. 9.5. 

 * Waclismuth and Springer, Revision of tiie Palaeocrinoidea, pt. iii., Proc. Acad. Nat. 

 Sci. Philad., 1885, p. 314. 



5 Geol. Mag., Dee. iv., vol. iv., Is07, p. 344. 



