the Greensand compared with tJiose of existing SiJecies. 123 



Haldon deposit, all come from a sponge or sponges closely 

 allied to, if not identical with, Dactylocalyx jiolydiscus ; in 

 which case we appear to have the species still extant. 



Not so, however, with figs. 1 and 2, which, with their like, 

 are equally abundant. These disks, in addition to the differ- 

 ence of branching off almost close to the shaft, are much more 

 lacinulated than any of the figs. 3, 4, and 5 ; besides which, 

 the ends of the branches are not rounded. Indeed the cha- 

 racters are so distinct and so different from those of the disk 

 of Dactylocalyx poly discus^ or any other species of Dactylo- 

 calyx with which I am acquainted, that I do not hesitate to 

 designate them by the name of " Dactylocaly cites Vicaryi^'' 

 in honour of Mr. W. Yicary, of Exeter, to whom we are not 

 only indebted for the discovery of these spiculiferous deposits, 

 but for that of many other important geological facts in this 

 neighbourhood. Fig. 6 is a lateral view of this disk. 



It is possible that if the filagree terminations of the lacinu- 

 lated disks of McAndrcwia azorica, Gray (for good illustra- 

 tions of which see Bowerbank, Proc. cit. 1869, pi. v. figs. 2 

 and 3), were broken off, we might produce figiu-es something 

 like 1 and 2 ; but in no instance have I observed the least 

 remnant of a termination like these to the branches of Dactyo- 

 calycites Vicaryi. 



Lastly, the heads, figs. 40 and 41, 42, PI. IX., also appear 

 to have belonged to the Coralliospongiffi, especially the latter, 

 viz. figs. 41, 42, whose elliptical disk and sinuous margin 

 so cause it to differ from all the rest, that for this I would 

 propose the name of ^^ Dactylocalycites ellipticusr Of fig. 40 

 I have only found two specimens ; they are very small, but 

 are so beautifully marked, that for these the most approj^riate 

 appellation that I can think of would be Dactylocaly cites 

 callodiscus. It should be remembered that wc are here naming 

 spicules only, and not entire sponges. 



In figs. 10 to 18 inclusively we have specimens of " knots," 

 so to call them, or branching centres of tlie silicified fibre 

 of the Coralliospongise and Euplectellidae, the rectangular 

 branching of figs. 10 and 11, and the hexradiate appearance 

 of figs. 10 and 15, being more particularly like that of the 

 sponges last mentioned. 



Fig. 12 is an instance of the canalled silicified fibre cha- 

 racterizing Farrea occa, Bk. (Proc. cit. 1869, pi. xxiv. fig. 1 

 and Brit. Spong. fig. 277). 



And the rest may be siliceous knots from the Dactylo- 

 calycidffi generally. 



In PI. VIII. figs. 19 to 29 inclusively, we seem to have 

 nothino; but the coarsest parts of the silicified fibre of the 



9* 



