PISCES. 



89 



No. 338. Ptychodus decurrens, Agass. 



Group op Teeth. The teeth of this Cesteaciont are of large size and of a 

 more or less square form. The crown of the tooth is deeper than the root, and 

 the summit is granulate at the margin. This specimen was found in the Chalk 

 at Kent, England, and is in the British Museum. Size, 6x3. Price, $2.00. 



No. 339. Ptychodus decurrens, Agass. 



Two Teeth. From the same locality and Museum. 



Price, $1.25. 



No. 340. Ceratodus . 



Two Teeth. The teeth of this Cestraciont are puzzling from the variety of 

 shapes they assume. They have in general an uneven or undulating tipper sur- 

 face of dentine and enamel, and an under-layer of reticulated osseous tissue. 

 These specimens are from the Upper Trias (Keupef ) at Stuttgardt, Wirtemberg, 

 and are now in the Ward Museum of the University of Rochester. Price. $0,80. 



No. 341. Notidanus esimius, Wagn. 



Skeleton, on slab. (Young). The teeth of this Shark, instead of having 

 one conical point, have a series of unequal sharp points, resembling in this re- 

 spect the lower jaw-teeth of the living " Grisets." This specimen was found in 

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

 Museum of the University of Munich. Size, 8x4. Prise, $1.00. 



No. 342. Mesturus verrucosus, Wagn. 



Skeleton, on slab. This fine fossil Fish is from the same locality and 

 Museum as the preceding. Size, 22 x 14. Price, $4.00 



No. 343. Edestes 



Leidv. 



Portion op Dorsal Spine. This remarkable ichthyo- 

 dorulite was discovered in the Coal Measures of Indiana, and is 

 preserved in the Cabinet of Amherst College It is distinguish- 

 ed for the large proportional size of the marginal teeth and 

 their close resemblance to the jaw-teeth of Carcharias, their 

 enamelled border being finely denticulate. 



Size, 9x3. Price, $1.50 



No. 344. Ichthyodorulite. 



Fossil Dorsal Spine, on slab. From the Lias of Lyme-Regis, England 

 and now in the Ward Museum of the University of Rochester. 



Size, 14 x 4. Price, $2.00 



No. 345. Ichthyodorulite. 



Fossil Dorsal Spine, 

 on slab. From the same lo- 

 cality and Museum as the 

 preceding. 



Size, 20 x 5. Price, $2.25. 



