ISCHADITES. 129 



Dictyophyton Danbyi is readily distinguished by its small size and the slighter 

 character of its spicular framework from other species of the genus. The speci- 

 mens represented on PI. II, figs. 4, 4 a, are the type-forms described by M'Coy, 

 now in the Woodwardian Museum at Cambridge. The other specimen, 4 b, repre- 

 sents the concave impressions of two individuals which, with the imperfect casts 

 of five others, are exposed on the surface of a small slab of rock, now in the 

 Museum of the Geological Society, Burlington House. 



Distribution. — Silurian : Upper-Ludlow-beds at Brigsteer, Benson, Under- 

 barrow, Kendal, Westmoreland. 



12. Hyalostelia gracilis, Hinde, sp. nov. Plate I, figs. 5, 5 a — 5 e. 



The form of the Sponge unknown, the detached spicules referred to the species 

 are either simple hexactinellids with the normal number of rays, or modified 

 spicules in which one ray or one axis is absent. The vertical axis of the spicules 

 is generally longer than the transverse, and varies in length from '675 to "95 mm. 

 The transverse rays are generally imperfect ; in some cases they form an oblique 

 angle with the vertical axis of the spicule. The spicular rays, with one exception, 

 are smooth and tapering, and apparently terminate obtusely. They vary from 

 •05 to "2 mm. in thickness. The rays in one spicule are furnished with obliquely 

 projecting spines. 



Associated with the body-spicules are some fragmentary, elongated, cylindrical 

 rods, about "12 mm. in thickness, with, in places, minute spines disposed spirally, 

 which may be portions of anchoring spicules. Both these and the body-spicules 

 are siliceous, and their axial canals are usually preserved. 



These various forms of spicules were discovered by Mr. J. Smith, of Kilwin- 

 ning, mingled together in a bed of decayed limestone, and it is probable that they 

 belong to the same species. 



Distribution. — Silurian : Wenlock strata, near Craven Arms, Shropshire (J. 

 Smith). 



13. Ischadites Lindstrcemi, Hinde. Plate II, figs. 2, 2 a. 



1884. Ischadites Lindste(emi, Hinde. Quart. Journ. Geol. Soc, vol. xl, 



pi. xxxvi, fig. 2. 

 — G-RiNDBODi, ? Salter, MS. (See Bigaby's Thesaurus Siluricus, 



p. 4, 1868.) 



