BllITISH FOSSILS. 



Decade VIIL Plate II. 



ASTERACANTHUS VERRUCOSUS. 



[Genus ASTERACANTHUS. Agassiz. (Sub-kingdom Vertebrata. Class Pisces. 

 Order Placoidei. Family Cestraciontidse.) Dorsal spine large, tuberculate, with a double 

 row of processes on the posterior margin ; base smooth.] 



Asteracanthus verrucosus^ Sp. Nov. 



Description. — The genus Asteracanthus, although for the most 

 part an oolitic form, extends nevertheless upwards into the Tilgate 

 beds, as shown in the preceding article. The typical species, 

 Asteracanthus ornatissimus, is a fossil of the Kimmeridge clay. 

 The remarkable character of this Ichthyodorulite attracted the 

 notice of collectors at a very early period. On the 29th of March 

 1753, a paper, by Mr. Henry Baker, was read before the Royal 

 Society entitled, " An Account of some uncommon Fossil Bodies."' 

 This paper is printed in the Philosophical Transactions of the Royal 

 Society for that year. The specimens described and figured are a 

 spine of a Hybodus, from Aust Passage, and several examples of the 

 Shotover-hill Asteracanth. The detailed descriptions, as also the repre- 

 sentations, are tolerably accurate, but the conclusion drawn is, that 

 the general appearance of these fossil bodies gives reason to conjec- 

 ture, that they are bones belonging to the head or snout of some animal 

 of the fish kind, or perhaps of some lizard, alligator, or crocodile." 

 The credit of determining the true nature of these curious fossils is 

 due to Doctor Buckland and Sir Henry De la Beche, who some years 

 ago prepared a joint paper on the subject, which unfortunately was 

 never published. The facts and materials collected by these authors 

 were liberally conceded to Professor. Agassiz^ when engaged on his 

 valuable publication on Fossil Ichthyology, and he stamps with liis 

 authority the correctness of their opinions. The very elegant fossil 

 which forms the subject of this article belongs undoubtedly to 

 the genus A st&r acanthus, but difiers specifically from all those 

 hitherto described. The length of the specimen is 10^ inches, but 

 the apex is wanting to the extent of perhaps ^ an inch. Taking 

 the length as 11 inches, the base of the front of the spine occupies 

 [viii. ii.] 8 c 



