126 



MOLLTTSCA. 



No. 524. Ammonites perarmatus, Sow. 



From Oxford clay (Middle Oolite) Calvados, France, and in the private Geo- 

 logical Cabinet of Mr. Ward, Rochester. Diameter, 6. Price, $1.10 



No. 525. Ammonites planicostatus, Sow. 



This small form would appear to belong to the group " Gapricorni," but as it 

 increases in age, it assumes a single row of spines in some instances very largely 

 developed, and thus puts on the character of the group " Armati" and becomes the 

 A. Dudressieri, D'Orb. This specimen is a slab covered with numerous shells, 

 and is from the Lower Lias, Dorset. It is now in the private Geological Cabinet 

 of Mr. Ward, Rochester. Diameter 12. Price, $1.50. 



No. 526. Ammonites refractus, De Haan. 



Two specimens on slab. This species is remarkable for 

 the manner in which the last whorl loses the spiral and Am- 

 monite-forrn arrangement, reminding us somewhat of a dis- 

 torted Scaphite. It is probably an aberrant form of the group 

 " MacTocepJicdi." From theMiddle Oolite, Gammelshausen, 

 Wirtemberg. Price, $0.40. 



No. 527. Ammonites radiatns, Brug. 



This form is the type of Von Buch's group " Flexuosi" the members of which 

 belong to the Neocomian. From the lower Cretaceous, Auxerre, France, and 

 now in the private Geological Cabinet of Mr. Ward, Rochester. Price, $0.60. 



No. 528. Ammonites raricostatus, Ziet. 



From the Lower Lias, Charmouth, England, and now in the private Geologi- 

 cal Cabinet of Mr. Ward, Rochester. Price, $0.50. 



No. 529. Ammonites Rhotomagensis, Broug. 



This is the type of the group " Rhotomagenses," the members of which are 

 characterized by having a series of tubercles along the dorsal line in place of 

 a keel. They belong chiefly to the Cretaceous period, From the Lower Chalk 

 Rouen, France, and now in the private Geological Cabinet of Mr. Ward, Roches- 

 ter. Diameter, 9. Price, $1.50. 



No. 530. Ammonites Rhotomagensis, Brong. 



An internal cast of part of one whorl showing the foliations. From the same 

 locality, and now in the Ward museum, University of Rochester. 



Diameter, 7. Price, $0.80. 



No. 531. Ammonites serpentinus, Schloth. 



This is the type of the group " Falciferi," 

 which have a compressed shell with sharp 

 keel. From the Upper Lias, Charmouth, Eng- 

 land, and now in the private Geological Cabi- 

 net of Mr. Ward, Rochester. 



Diameter, 6. Price, $0.80. 



