22 BRITISH FOSSIL SPONGES. 



118. 1872 Schluter, C. A. Ueber die Spongitarien-Baenke der oberen Quadraten 



und unteren Mukronaten-Sckichten des Miinsterlandes (Sitzungsb. 



d. Niederrhein. Gesells., pp. 1 — 38, PI. 1). 

 Describes in detail the characters and stratigraphical distribution of the 

 various Sponges in these beds, and constitutes two new genera of hexactinellid 

 Sponges, Lepidospongia and Becksia, 



119. ]873 Salter, J. W. Catalogue of Cambrian and Silurian Fossils in Geol. 



Museum, Cambridge. 

 The forms referred to Sponges are placed under Amorphozoa. It is stated 

 " that Stromatopora, Coscinopora, Cnemidium, Verticillopora, Stellispongia, Sfc. y 

 are examples of very solid calcareous Sponges. Ischadites, Sphcerospongia, 

 Amphispongia, and other Silurian forms, are supposed to be distantly allied to 

 the living Grantia" Ischadites Kcenigii is figured erroneously with stem and 

 roots. 



120. 1873 Carter, H. J. On the Hexactinellidas and Lithistidge [Ann. and Mag. 



Nat. Hist., vol. xii, p. 349, 437, Pis. xiii, xvii). 

 Refers in detail to the spicular structure of these groups as shown in 

 existing species, and comparisons are made in one or two cases with fossil 

 forms as well. 



121. 1873 Fisher, 0. On the Phosphatic Nodules of the Cretaceous Rocks of 



Cambridgeshire. 

 Refers to their constitution, and regards many of them as having originally 

 been Sponges. 



122. 1873 Sollas, W. J. On the Ventriculitae of the Cambridge Upper Green- 



sand (Quart. Journ. Geol. Soc, vol. xxix, pp. 63 — 70, PI. VI). 

 Describes the minute structure of the Ventriculite skeleton, which is stated 

 to consist of the " regular anastomosis of a number of hexaradiate elements, 

 each of which consists of six radial fibres, apparently tubular, diverging from 

 a common centre, at right angles to each other." The constitution of these 

 fibres is not stated, but the author mentions that he failed to find spicules, 

 either in silicified or phosphatised Ventriculites. The silicified Ventriculites 

 are regarded as instances of the silicification of highly decomposable animal 

 matter, and the phosphatic Ventriculites ' are striking examples of the phos- 

 phatisation of soft-bodied animals/ The presence of siliceous Xanthidia and 

 Polycystina in the Coprolites is adduced as ' an argument against regarding 

 the Ventriculites as having originally had a siliceous skeleton which had sub- 

 sequently been replaced by phosphate of lime.' " 



