30 



.Mil I AN KL-ER. 



[SEC. ARCT. KXT. IK AM 



of tin- structure, although of course transformation hy pyrites had its 



unpleasant effects. 



I'l. III. figs 5 (J are direct photographs of my microscopic sections 

 and in compai -i>on with the other illustrations of microscopic section.- of 

 Psammost&US remain.-. >lm\v a complete agreement with that genus. 

 ! :u. li. iin the text) gives us a more diagramatical view of the .structure 

 with clearer details. It pas-.es trough hoth the upper and the lower 

 hodv plate. The tish has heen pressed >o strongly in the schists that 



I'll. 1 . <'. Skcli'll s|m\vin; Hie slnnlliri' nf till' ilcniiill -kflclnil ill Di f'Jl 

 GemiindenensiS, NHM'III;. Tin- -ri-lnin is inailt- through one l Hit 1 uppi-r an I 

 nf UH- IIIUIT liiniy plalf-. 'I'lic lallrr arr -u ^really compressed Hull Hit 1 iiuim>l 

 la\cr nl' Ilic -ki-lrliHi i> i-ni~lii-il. At tlif rxlivini' tup and liuttoiu \vc scr tin- drn- 

 lirli'- \\ilh Ilinr \viilc |nilp cavilic- ami line ilcnliiic tulmlrs; below tlicni is tin- 



\a-i-iilar ranal syslnn. 



Imlii of these pl.-ile.s h;i\c pres-ed against each other and partly crn>hed 

 in the inner parts. <MhT\vise in this and in the said plate we see the 

 vascular canal system, with uarro\\ canals and orifices in the upper part 

 and more open ones in the lower. Thus on the upper surface we have 

 the denticles \\ilh fine dentine Inhules and very wide pulp cavities, 

 which are in connection hy means of a hroad orifice with the underlying 

 \as.-nlar canaU. I !\ their characteristic form, these denticles constitute 

 the surface sculpture. This was not very thoroughly descrihed in 

 'h;.\oi UR'S \\orks. nor do his illustrations convoy so exact a picture 



