Mr. H. J. Carter on Fossil Sponge-spicules. 211 



although I have been able to find a few with slightly different 

 forms, which have assisted me in the following descriptions. 

 Of course, as drift-spicules, which these must have been 

 when originally deposited, to say nothing of the subsequent 

 effects of fossilization &c, they are nearly all fragmentary ; 

 but sufficient of them remains for easy recognition and for 

 restoration, as will be seen by the illustrations. 



First and foremost is a sexradiate stellate (PI. XIV. B. 

 fig. 2), which in number of rays varies from 6, 12, 18 to 24 

 (figs. 4-7), according to the amount of division of the extre- 

 mities of six arms. The stellates vary in size from l-75th 

 to 5-24ths of an inch (fig. 1) in diameter ; and the smallest 

 are not only the most numerous and have the greatest number 

 of rays, but, as the latter often arise from a division of the 

 arm close to the centre, they acquire the appearance of 

 globular little stars ; while, where the arms are a little more 

 extended, they often present the appearance of a "Maltese 

 cross." But the most striking feature of this spicule is 

 that, from the smallest to the largest, each ray is spiri- 

 form ; that is, its surface presents a spiral inflation in which 

 the coils are more or less numerous, extending from the base 

 to the apex of the ray (figs. 2 and 3) ; where they are most 

 numerous they, of course, are more transverse, and then ap- 

 pear like separate annulations; while the most remarkable 

 difference in them is confined to the rays of the largest stel- 

 lates, where, towards the base, the spiral line of inflation 

 becomes broken up into short portions (fig. 3, b), which look 

 very much, from their alternate arrangement in adjoining- 

 coils, as if this had been produced by another spiral groove 

 pursuing an opposite direction (that is, across the original 

 inflation). 



This fossil spicule is incomparably more numerous than the 

 other spicular forms accompanying it ; so that, together with 

 its peculiarities being confined to a stellate form, I am com- 

 pelled to think that it must have belonged to a species of 

 Holasterella which, if found in situ hereafter (that is, forming 

 the entire sponge), will be like H. conferta • hence I have much 

 pleasure in naming it Holasterella Wrightii, after its disco- 

 verer. 



The next spicule in frequency appears to have been a 

 hexactinellid, with the sixth or external arm not produced as in 

 the large surface-spicules of the Sarcohexactinellida, in which 

 four arms arc extended over the surface laterally, while the 

 fifth, like the shaft of a nail, goes vertically inwards (fig. 8). 

 With this, and also equally plentiful, are the free ends of 

 " anchoring-spicules " terminated by four much-recurved 



