I?f THE LOWER TEETIAET STBATA OF KEW ZEALA.XD. 235 



Sponge Spic. p. 35, pi. ii. figs. 17, 18) aud in the xeeeut Craniella 

 (Tetliea) cranium (see Mon. Brit. Spong. vol. i. pi. 31. fig. 362 «). 



Thenea (a).— PI. XIII. fig. 18. Trifid spicule Avith slender 

 tapering shaft, rounded harpoon-like head, and long, slender, 

 strongly recurved head-rays. The shaft is incomplete, it is "01 

 mm. in thickness; the head-rays are "128 mm. in length by "01 

 mm. in thickness. This spicule resembles the trifids in the 

 recent Thenea {Tisiplionia) fenestrata, Osc. Sch., sp., as figured in 

 the ' Challenger ' Eeport (vol. xxv. pi. viii. fig. 3), but the rays 

 are less elongated. 



PI. XIII. figs. 20-24 a. Trifid spicules with elongated shafts 

 and simple head-rays, recurved at diff"erent degrees. The shafts 

 vary from "03 to "04 mm. in thickness ; the head-rays are from 

 •07 to '2 mm. in length. Though the difl'erences in form are 

 slight, yet, judging from recent sponges, these anchor trifid 

 spicules probably represent four or five species. A detached 

 spicule nearly similar to 24 a is present in the ' Egeria ' dredgiugs 

 from ofi^ the S.W. coast of Australia, at a depth of 2479 fathoms. 



The trifid spicules referred to above are very abundant in some 

 portions of the Oamaru material, where they constitute the major 

 portion of the sponge-spicules present, in other portions of the 

 material they are somewhat rare. It is difiicult to determine the 

 number of species they may represent, possibly not more than 

 five or six, and equally difficult to refer them to particular 

 genera, since this chiefly depends on the character of the flesh - 

 spicules associated with these skeletal forms. Trifid spicules of 

 the same character as those figured are common wherever sponge- 

 spicules occur in the older rocks, and they are known from the 

 Carboniferous formation upwards, being specially abundant in 

 the Lower and Upper Greensand and in the Upper Chalk of this 

 country. As detached forms, they are numerous in recent 

 dredgiugs, and they occur from off the S.W. coast of Australia 

 in material from a depth of 3000 fathoms. 



Globate Spicules o/" G-eodites, Carter. 



PI. XIY. figs. 32, 32 a. Globates varying from nearly spherical 

 to ellipsoidal in form. An ellipsoidal specimen measures "093 

 mm. by "04 mm., whilst a nearly spherical individual is '121 mm. 

 by '095 mm. These spicules are fairly abundant in the Oamaru 

 deposit, and they show the same structural details as the globates 



