Notices of Memoirs — E. Koken — On Thoracosaurus. 169 



UOTICES OIF MEMOIES. 



I. — New Species of Fossil Sponges from the Siltjro-Cambrian 

 at Little Metis on the Lower St. Lawrence. By Sir J. 

 William Dawson, LL.D., F.R.S. (Including Notes on the 

 Specimens by Dr. G. J. Hinde.) Transactions of the Royal 

 Society of Canada, vol. vii. section iv. 1889, pp. 31-55, pi. iii. 

 and 27 figs. 



IN some black shales, belonging to the Quebec Group of Logan, 

 exposed on the shores of the Lower St. Lawrence, Sir W. 

 Dawson discovered some thin bands, largely filled with sponge- 

 remains. In some instances the general form and outlines of the 

 sponges have been preserved in a compressed condition, but more 

 often the thin beds consist of a mass of spicules irregularly com- 

 mingled together. In all cases the original siliceous structure of 

 the spicules has disappeared, and they are now composed of pyrites. 

 The sponges appear to belong almost exclusively to the Hexac- 

 tinellidaj ; the genus Protospongia is represented by six new species, 

 Cyathospongia (Cyathophyciis), Walcott, by one species, and Byalo- 

 stelia one species. A new genus, Acauthodictya, is proposed for 

 cylindrical sponges with a dense fringe of spicular rays on the 

 exterior, and some small oval sponges, in part at least apparently 

 composed of simple acerate spicules, are placed in the new genus 

 Lasiothrix. The specimens of Protospongia are more complete and 

 better preserved than any hitherto known, and they are furnished 

 with anchoring spicules, a structural feature not previously recognized 

 in this genus. In one species, P. tetranema, the number of the 

 anchoring rods is limited to four, and the author thinks they con- 

 sisted of a single crucifoi'm spicule of which the rays were bent 

 upward and lengthened, forming a stalk for the sponge. It may be, 

 however, that the rods are simple, and that the apparent union at 

 their distal ends is not original, but produced in the fossilization. 

 In another species, P. coronata, there is a distinct collar of curved 

 spicules surrounding the cloacal aperture. Judging by the characters 

 of the detached spicules many other additional species were probably 

 present in these sponge-beds. 



The only other recognizable fossils found in connection with these 

 sponges are a small Brachiopod referred to OboleUa (Linnarssonia) 

 pretiosa, Billings, and some slender plant (?) remains which are 

 named ButhotrepMs pergracilis. The exact horizon of the black 

 shales is not precisely determined, but Sir W. Dawson regards them 

 as probably near the base of the Levis division, or equivalent to the 

 English Arenig. 



II. — Thoracosaurus macrorhynchus, Bl., aus der Tuffkreide von 

 Maastkioht. By Ernest Koken. Zeitschr. deutsch. geol. Gesell., 

 1888 (1889), pp. 754-773, pi. xxxii. 



A FINE Crocodilian cranium, evidently from the Maastricht Beds, 

 now preserved in the Leiden Museum, forms the subject of 

 this memoir. A detailed description and comparison proves the 



