IN THE LOWER TERTIARY STRATA OE NEW ZEALAND. 189 



PL YIII. fig. 5. Tibiella with smooth, evenly cylindrical, 

 regularly curved shaft and prominent club-shaped ends. Length 

 •133 mm., thickness '003 mm. 



PI. VIII. fig. 6. Tibiella with smooth, cylindrical, slightly 

 curved shaft and club-shaped extremities which are minutely 

 spined. Length '106 mm., thickuess "003 mm. Similar spiculest 

 occur in lophon cylindricus, Eidley & Dendy (Chall. Eep. vol. xx. 

 p. 120, pi. xvii. fig. 6 c), from ofE Cape Howe, Australia, at a depth 

 of 120 fathoms. 



The examples of tibiella spicules figured above indicate a con- 

 siderable variety of form and size in the Oamaru material and 

 they are likewise very abundant. They range from "106 to '765 

 mm. in length, and from '003 to "06 mm. in thickness. Tibiella 

 spicules are present in the following genera, amongst others, of 

 recent sponges : — Histo derma, Carter, Tedania, Gray, lophon, 

 Gray, Myxilla, Osc. Sch., JForcepia, Carter, Sideroderma, Eidley 

 & Dendy, and also in some of the species placed under Hali- 

 chondria by Carter and Bowerbank, and in Phloeodictyon, Carter. 

 It will be shown further on that the distinctive flesh-spicules of 

 several of these genera are present in the deposit. Detached 

 tibiella spicules are present in dredgings off the S.W. coast of 

 Australia at a depth of 2479 fathoms. 



Acuate or Styliform Spicules of various Genera. 



PI. yill. fig. 7. Acuate, with evenly rounded head, the 

 upper half of the shaft nearly of an even thickness, then gradually 

 tapering to an acute point. Length "385 mm., thickness 

 •008 mm. 



PI. VIII. fig. 8. Large, stout, slightly curved acuate, of an 

 even thickness for about two-thirds from the head, thence 

 gradually tapering. Axial canal widest near the head and 

 gradually diminishing to the apex. Length 1*5 mm., thickness 

 •03G mm. This is the largest form of acuate met with in the 

 deposit. Shorter but otherwise similar spicules are present in 

 Amphilectus annectens, Eidley & Dendy (Cliall. Eep. vol. xx. 

 p. 127, pi. xix. fig. 4), and also in A. pilosus, E. & D. (1. c- 

 p. 126, pi. xix. fig. 5), from Kerguelen. 



PI. VIII. fig. 9. Nearly straight acuate, of approximately the 

 same thickness to within a short distance of the apex. The head 

 is slightly inflated but hardly sufficient to include it with spinulate 

 forms. Length "285 mm., thicknetis '006 mm. 



