362 



preserved, coriaceous in substance, showing no mid rib, and only 

 a blurred outline of organs of fructification. These, particulars 

 harmonize with my first account, and the evidence of thera 

 taken together is amply sufficient to lead ns to place the depth 

 of the Spinatus beds in the Laminarian division of the liassic 

 shore. Those desirous of more precise information of the 

 character and dimensions of our larger recent marine algse, 

 should refer to the works of the late Professor Haevet. In his 

 Manual of Brit. Marine Algse, p. 27, (Van Voorst, 1849,) my 

 friend says of the order Laminariacece, " The plants of this 

 family are almost all of large size, and many of them gigantic, 

 greatly exceeding in bulk any other marine vegetables. The 

 oar-weeds and tangle of our own coasts have frequently stems 

 six or eight feet long, and fronds expanding from their summits 

 to as great a length ; and the seathong (Chorda) often measures 

 40 feet in length. But these dimensions are small compared 

 with their kindred on the shores of the Pacific Ocean. The 

 Nereocystis a plant of this family, inhabiting the north- 

 western shores of America, has a stem no thicker than 

 whipcord, but upwards of 300 feet in length, bearing at its 

 apex a huge vesicle six or seven feet long, shaped like a barrel, 

 and crowned with a tvift of upwards of 50 forked leaves, each 

 from 30 to 40 feet in length. The vesicle being filled with air, 

 buoys up this immense frond, which lies stretched along the 

 surface of the sea. Here the sea-otter has his favourite lair, 

 resting himself upon the vesicle, or hiding among the leaves 

 while he pursues his fishing. In length it is exceeded by the 

 Macrocystis. In Macrocystis, the stem branches, as it approaches 

 the surface, and afterwards divides by repeated forkings, each 

 division bearing a leaf, until there results a floating mass of 

 foliage some hundreds of square yards in superficial extent." 



The only palaeontologist who has devoted himself to the 

 special study of liassic AlgEe is the Count Gaston de Saporta, 

 of Aix, who is now bringing out a work on the fossil Algse of the 

 Jurassic seas. They are, from their nature, and the imperfection 

 of specimens, a difficult class of fossil to study. The predominant 

 form in these Chm-chdown fossils bear a close likeness to a 



