376 



Reviews — Prof. Dr. G. Lindstrbm — 



The memoir opens with an introduction, containing a description 

 of the Cephalopoda beds of Gotland : these represent the " Ludlow 

 beds" (190 feet), the " Wenlock shale" (80 feet), and the "Upper 

 Llandovery" (thickness unknown). In the uppermost of these beds 

 immense masses of the shells of Cephalopoda occur, the strata (4 or 

 5 feet thick) being made up almost entirely of them, in some places. 

 From the vast quantities of these shells, of all sizes, thus heaped 

 together, the author supposed that they were washed ashore, as the 

 shells of Spirula are at the present day on the shores of the Pacific 

 islands. 



a, Schematic view of the interior of Ascoceras manubrium, Lindstr., showing the 

 structure and arrangement of the septa ; si, siphuncle ; df, duct that communicates 

 ■with the siphuncle of the Nautiloid portion of the shell (seen, Fig. f) ; b, schematic 

 view of three sigmoid septa of Asc. fistula, Lindstr., seen from the ventral side; 

 c, view of the third septum of the same species, shown as free, as if removed from 

 the shell, to exhibit the large central lacuna ; d, the same viewed laterally (the 

 siphuncular orifice is seen at the bottom of all these figures) ; e, longitudinal section 

 of a specimen of Asc. decipiens, Lindstr., from Sandarfve Kulle, with four regular 

 septa above the sigmoid ones ; f, schematic view of Asc. decipiens, represented as if 

 complete — n, the Nautiloid portion of the shell ; g, longitudinal and median section 

 from the concave to the convex side, of Cboanoceras mutabile, Lindstr., showing 

 the interior of the shell, with the outlines of the incomplete septa— si, siphuncle; 

 h, fragment of the same species, reduced to about -|- natural size. All the figures 

 are copied from Lindstrom's plates a — d, reduced from ^ to £ natural size; e — G 

 are the same size as the original figures. 



After reviewing in considerable detail the work done by various 

 authors, chiefly German and Swedish, in connection with Gotland 

 Cephalopoda, including Klein, Breynius, Hisinger, Schlotheim, 

 Wahlenberg, Marklin, Angelin, Boll, and Barrande, Dr. Lindstrom 

 commences his description of the Family Ascoceratida?. 1 In this 



1 The fossils described in this memoir belong mostlv, we are told, to the Palaeon- 

 tological Department of the Swedish State Museum at Stockholm. 



