22 Mr. II. J. Carter on the 



instances the rajs are scarcely of larger diameter than the 

 filiform spicules, in others they are several times as large, and 

 appear giants by comparison (No. 9, p. 355). 



Now, as these are forms which I have more or less witnessed 

 myself under similar examination, and we are only on the 

 threshold of our knowledge respecting them, partly from the 

 want of observers, but principally perhaps from the difficulty 

 of the subject, it may not be unacceptable to state what I 

 myself have seen. 



Thus the u filiform spicules " which I find very numerous 

 in the fibre of my specimens of ? Manon peziza (No. 7, Taf. 

 cxxxii. fig. 30) and ? Scyphia perplecea (No. 7, Taf. cxxv. 

 fig. 63), wherein, on account of their regular parallel outlines 

 and flexuous course, they look very much like the filaments of 

 Confervas, are for the most part truncated by the thinness of 

 the slice, and thus present themselves in a fragmentary state, 

 in which it is difficult to find one with a natural termination. 

 Where the section has caused them to be truncated horizon- 

 tally (that is, where the fibre has been cut directly across and 

 they appear under the microscope as if ascending from below) , 

 their ends are seen to be circular and to present a punctum in 

 the middle, indicative of an axial canal. They occupy the 

 outer part of the fibre, and thus frequently become entwined 

 round the axis of a colossal shaft (" giant by comparison/ 7 as 

 Prof. Sollas expresses it), which we shall find by-and-by to 

 be a characteristic feature of the spiculation in some of these 

 sponges ; or the axis may present a comminuted appearance, 

 in which they often appear to have their origin, which 

 u comminuted appearance," partly obscured in flocculent 

 matter, appears to be the remains of a half- dissolved chain of 

 triradiates, rendered still more indistinct perhaps by being on 

 their edges and having their arms cut off both above and 

 below by the section. But be this as it may, to obtain the 

 entire forms of the spicules in this fibre by such thin slices 

 can only be the result of accident extended over long periods 

 of examination, being almost as difficult as discovering the form 

 of a knot of twine by a thin slice through its centre. 



As the filiform spicules pursue their course along the reti- 

 culated fibre, they not only cross each other obliquely, so as 

 to sheathe as it were the axis, but partly surround the fenestral 

 openings in the fibre itself in such a manner as to give an 

 appearance of great original flexibility, while together they 

 must thus have formed a densely filiferous cord by inter- 

 twining; with each other, and this, through anastomosis, must 

 also of itself have produced a reticulated self-supporting struc- 

 ture without the calcitic incrustations which now invest it. 









