90 veetebeata. 



Order 3 — Cycloids. 



These osseous Fishes are distinguished by their circular, imbricated, 

 unenarnelled scales with concentric markings. The dorsal fin is spiny, 

 as in the Mackerel, or Soft-rayed, as in the Salmon. 



This Order is not represented by any species of older date than the 

 Cretaceous epoch. The Chalk has yielded 21 species, and the Tertiary 

 154. Nearly all belong to extinct genera. 



Order 4 — Ctenoids. 



This Order includes the Teleostian Fishes with comb-like scales, 

 generally of a rounded or ovoid form, and spiny dorsal fin, like the 

 Perch. 



They were ushered into being along with the Cycloids. Of the 195 

 fossil forms described, 11 are from the Chalk. 



No. 346. Beryx SUperbtlS, Dixon. 



Group, on slab. The genus Beryx, of which 

 there are two existing species in the Australian 

 seas, represented the Perch family during the 

 Cretaceous period. The characteristics are a large, 

 blunt head, one dorsal fin with several spinous 

 rays in front of the soft ones, and large, round, 

 pectinated scales. This specimen was found in 

 the Lower Chalk at Lewes, England, and is in the private Cabinet of S. H. Beckles, 

 Esq., of Brighton, England. Size, 23 x 14. Price, $12.00. 



No. 347. Holocentrum pygseum, Agass. 



Skeleton, on slab. This genus, still represented in the Pacific Ocean, be- 

 longs to the same family as Beryx. This species is shorter and stouter than the 

 living one, with a larger head and smaller anal fin. The specimen is from the 

 Middle Eocene beds of Monte Bolca, Italy, and is in the private Geological Cabi- 

 net of Mr. Ward, Rochester. Size, 6x3. Price, $1.50. 



No. 348. Cololites, Agass. 



These tortuous and convoluted intestinal-like masses and impressions have 

 been called Luinbricaria, Miinst., from the supposition that they were worm- 

 casts. But Prof. Agassiz considers them the petrified intestines of Fishes or the 

 contents of the intestines which have preserved the form of the tube, and have 

 thus been fossilized. They are generally found isolated. This specimen is from 

 the Lithographic limestone (Upper Oolite) at Eichstadt, Bavaria, and is in the 

 Ward Museum of the University of Rochester. Price, $1.00. 



