PISCES. 



83 



No. 309. Holoptychins nobilissinms, Agass. 



• 

 Body and Head, on 

 slab. The Holoptychians 

 were Ganoid fishes be" 

 longing to the Coilacanthi, 

 or hollow-spined, and are 

 characterized by the large, 

 deeply corrugated scales 

 covering the body, and the 

 sculptured and granulated 

 plates defending the head. 

 The teeth are of two kinds 

 — small serial teeth and large laniaries, the latter placed behind the former. The 

 ventral fins are nearer the tail than in any other Ganoid. This splendid speci- 

 men, one of the ornaments of the British Museum, was discovered in the Old Red 

 Sandstone at Clashbinnie, Scotland, and is figured in Murchison's "Silurian Sys- 

 tem." The creature lies on its back. " The body (says Hugh Miller) measures a 

 foot across by two feet and a half in length, exclusive of the tail, which is want- 

 ing ; but the armor in which it is cased might have served a Crocodile or Alliga- 

 tor of five times the size." The head is short and obtuse ; the lower jaw, the 

 mouth, and the two branchial rays or plates are exposed. The scales are very 

 large and deeply wrinkled. Size, 2 ft. 9 in. x 1 ft. 4 in. Price, $5.50. 



No. 310. Holoptychius nobilissimus, Agass. 



Group, on slab. From the same locality as the preceding, and now in the 

 private Geological Museum of Mr. Ward at Rochester. 



Size, 2 ft. 4 in. x 1 ft. 2 in. Price, $5.50. 



No. 311. Rhizodus Hibberti, Owen. 



Lower Jaw, left ramus. The generic term Rldzodus is applied to those 

 Holoptychians of the Coal Measures which have stout serial teeth and slender 

 laniaries. The great strength of the cephalic plates and of the jaws and teeth 

 shows that this was a powerful carnivorous Fish. This fragment of the lower 

 jaw was disinterred from the Carboniferous Limestone, near Edinburgh, and is in 

 the British Museum. Size, 19 x 7. Price, $2.25. 



No. 312. Undina striolaris, Miinst. 



Skeleton, on slab. This hollow-spined, heterocercal Fish had pavement- 

 like teeth, fitted to crush small testaceous and crustaceous animals. This speci- 

 men was found in the lithographic limestone (Upper Oolite) at Kelheim, Bavaria, 

 and is in the Museum of the University of Munich. Size, 14 x 6. Price, $2.25. 



