BRITISH FOSSILS. 



Decade X. Plate VII. 



ACANTHODES MITCHELLI. 



[Genus ACANTHODES. Agassiz. (Sub-kiugdom Vertebrata. Class Pisces. Order 

 Goniolepidoti. Family Acanthodei.) Body fusiform. Mouth large, opening upwards. 

 Orbits encircled by four bony plates. Branchiaj exposed. Fins membranous, supported 

 by strong sjjines. One dorsal spine near the tail ; one anal below and slightly in advance 

 of the dorsal ; pectoral spines strong ; ventral spines small. Scales minute.] 



Synonym. Acanthodes antiquus, Egerton. Report of Brit. Assoc., 

 1859, p. 116. 



At the meeting of the British Association for the Advancement 

 of Science, held at Aberdeen in the month of September 1859, the 

 Eev. Hugh Mitchell, of Craig near Montrose, communicated to the 

 Geologfical Section a notice of the occurrence of fossil fishes in 

 the Old Red Sandstone formation in Forfarshire. A cursory ex- 

 amination of the specimens exhibited in illustration of the memoir, 

 satisfied me that the species discovered at Farnell were new to 

 science, and I consequently named the subject of the present article 

 Acanthodes antiquus. I subsequently saw two other new species 

 of the same genus from the Old Red Sandstone of Scotland, and, 

 therefore, cancelled the incorrect and objectionable specific afiix, 

 and substituted the name of the discoverer of this pretty and well 

 characterized species. 



Description. — The specimens I have examined of this pretty 

 little fish vary from two inches to two and three-quarters of an inch 

 in length. The one I have selected in illustration of this Memoir 

 measures two inches and a half. The deepest part of the body (PL VII,, 

 fig. 2.) is at a point midway between the pectoral and the ventral fins. 

 It here measures half an inch. The head measures about one-fifth 



