232 



THE CANADIAN NATrRAI.lfcT. [Vol. 



GenuR Amplkxuk. 



Til 



2. A. RXM-is. — Cornllum more or less curTcd, expanding to a 

 diutix^tor of 14 liiit-h nt 3^ inches from the Ixue. Surface vith 

 very dic<tiiK'tly defined costal striae, of whieh there are 5 in th« 

 width of 3 liiieH, where the diametar is aboat one ineh, and G or 

 7 ill the .same ppace at the base. There are about 64 septa where 

 the <lianieter is 14 lines. The larger of these are scarcely a lino 

 in depth ; the smaller about half that size. The tabulae are very 

 thin, flat or .<lightly undulating, distant from each other from 1 

 to () linen. 



Owing to the fragile character of the shell, good specimens of 

 this .species are rare. The best in our collection con.sists of the 

 lower G inches partly imbedded in the rock. By the application 

 of acid, the whole of the interior has been completely freed from 

 the lime>tnne which filled it, so that it shows the tabulae and 

 septa perfectly. Jt is curved, somewhat irregularly, i > a radius 

 of between 4 and 5 inches. There are numerous small rings of 

 growth, in general not very prominent, but with seme that are 

 angular and strongly elevated. These arc. sometime.', so deep 

 that they give to the costal Btriae. a .iodnse appearauce. 



The extremely ruilimentary state of the .sept i. tJistiiiguishes 

 this species from all the described American forms known to me. 



Occurs in the Corniferoug. 



— 3. A. MIKAKII.ls. — Corallum hometimes abruptly curved in 

 different directions, expanding to a witlth of from 15 to 20 lines 

 in a length of 4 or 5 inches from the base; above '.'hich it be- 

 comes more nearly cylindrical. Surface with fiiie engirlling 

 j*tria5, in general 4 or 5 in the width of 2'lineH, but in .><omo 

 places, the same number occur in the widtli of one line. There 

 arc also ntimerous angular rings of growth, distuiit from 2 to 15 

 lines from each other, with sub-concave spaces brtween. Septal 

 coHtic rounded, distinctly defined by sharp striae bt^tween them, 

 7 or H in the width of 3 lines m-ar the bas<', and 4 or 5 in the 

 same near the oalice. There are about 40 largo septa at thu 

 onlice, where the diameter is about 1H lines, with the same num- 

 ber of «mall ones between them. The larger have & depth of 3 

 or 4 lines and the smaller 1 line. All of the septa are more or 

 less curved, sometimes very tortuous. The tabuliie have not 

 been observed. 



The above description was drawn up from a specimen, 11 



