558 Transactions of the Society. 



even slightly inflated at the end or ends, according to the shape 

 of the enclosing spicule. But in some spicules there is no trace of 

 a canal in the axis, whilst in compound or branching ones, the 

 axial tube, still retaining its delicate appearance, may be as comph- 

 cated in its direction as the environing sihceous structure. The 



Fig. 5/. — Circular depressions crowding a spicule which has broken where 



penetration has occurred, axial tube slightly enlarged. 



„ 6. — ^Au acerate with a great enlargement of the axial canal, and an 



eroded appearance of the walls of it. 



6a. — With a symmetrical enlargement at one end, elsewhere normal. 



66. — "With a greater enlargement. 



6c. — A long acerate, open at both ends, with simple swellings. 

 6**. — Eroded surface of one of the spicula. 



7. — Fusiformi-cylindrical, bent more at the ends than in the middle, 

 blunt-pointed spicula. Spicule showing two enlargements and 

 mucli normal axial canal, whose extremities are closed ; many 

 penetrations. 

 7a. — Same shaped spicule, differently enlarged axial canal. 

 7b. — Same shape ; penetrations and enlargements. 

 76*. — Differently shaped enlargements. 

 7c. — Open axial canal, which is enlarged in two places considerably, and 



universally slightly. 

 Id. — Great and regular enlargement of two parts of the axial canal, with 



fracture at the ends. 

 7e. — Fracture from thinning, and granular appearance on the wall of the 



canal. 

 If. — Moniliform enlargements, and fracture at both ends. 

 7**. — An eroded axial canal wall. 

 8. — Fusiformi-cylindrical spicule, open at the ends and penetrated ; axial 



canal enlarged in two places. 

 8a. — A spicule with open axial canal, and solution has taken place of the 

 point of one. The enlargements are slight, and of the nature 

 noticed by Carter. 

 9. — A cylindrical and basally spined spicule with greatly enlarged axial 

 canal full of air except centrally where it is normal and has a 

 penetration. 

 9a. — An entirely spined spicule, with one perfect perforation and greatly 



enlarged canal. 

 96. — Fracture from thinning. 

 10. — A large entirely spined spicule, fractured along a line of thinning 



of a great expansion. 

 10a. — Penetrations into an axial canal, which is enlarged ; depressions on 



the surface of the spicule. 

 11. — Short, stout, curved spiculate, with normal axial canal and three 



incomplete perforations. 

 11a. — Open axial canal, and bulb part of another specimen ; canal 



enlarged. 

 12. — A penetration into a canal, enlargement close by. 

 12a. — Eroded axial canal. 

 126. — Normal canal, penetrations incomplete. 

 13. — Rtmarkably shaped axial canal. 

 13a. — Penetrations, fracture, and enlargements. 

 14. — A very long acuate, showing penetrations and enlargements, the 



axial canal being open. 

 15. — Erosion on the surface of the spicule, besides enlargement of the 



axial canal. 

 16a. — Zoospore-shaped-body, free in a concave depression with circular 

 outline. 



