4 LOWER GREENSAND. 



beautiful winged shells Bostellaria glabra, Forb., B. retusa, Sow., Pterocera Filtoni, 

 Forb., and several species of Cerithia, as Cerithium turriculatum, Forb., C. Neocomiense, 

 d'Orb., and C. Phillipsi, Leym. 



IV. The Lower Gryphaa or Exogyra Group has for its base a thick bed of ferrugi- 

 nous sand, overlain by sand containing Perna alaformis, Sow., and Terebratula sella, Sow., 

 in great abundance, in thin seams of sand. The zones with Exogyra sinuata, Sow., which 

 here are very large, are found in the upper part of the group. 



V. The Scaphites Group forms three beds ; the lowest is composed of brown ferru- 

 ginous sand, containing Exogyra sinuata, Sow., Terebratula sella, Sow., Bhynchonella 

 Gibbsiana, Sow. ; and of the Echinidae I found Cardiaster Benstedi, Forb., and Nucleolites 

 Olfersii, Ag. ; the middle beds, about two feet in thickness, contain layers of nodules 

 enclosing Scaphites gigas, Sow., and Scaphites Hillsii, Sow. ; the upper consist of thick 

 beds of greenish sand, containing, in the upper part, fine large specimens of Exogyra 

 sinuata, Sow. 



VI. The Loioer Crioceras Group consists of ranges of large sandy nodules, enclosing 

 Crioceras Bowerbanhii, Sow. ; the lowest range rises on the west of Whale Chine, and is 

 succeeded by two other ranges, all three enclosed in sand about nine feet thick ; the 

 lowest, furnishing the best fossils, passes the bottom of Whale Chine, from whence I 

 have obtained several large specimens. 



VII. The Walpen and Ladder Sands and Clay extend from the east of Walpen to half 

 way between Ladder and Whale Chines, where they are well seen ; the lower half of this 

 group contains Ammonites Martini, d'Orb., and a large Gryphcea ; the upper half, 

 which is clayey below and sandy above, contains Bentalium, Myacites mandibula, Sow., 

 Pinna Bobinaldina, d'Orb. 



VIII. The Upper Crioeeras Group consists of sandy nodules imbedded in sand, and 

 contains Crioceras Bowerbanhii, Sow., Ammonites Martini, d'Orb., Gervillia solenoides, 

 Defr., 'Terebratula sella, Sow., and several other shells. This group is seen for some 

 distance along the shore east of Walpen Chine, which is crossed by it, as are also Ladder 

 and Whale Chines. 



IX. The Walpen and Ladder Sands consist of greenish and gray sand, with a layer 

 of large fossiliferous nodules at the base, containing Serpuke, Thetis, Gervillia, Cucullaa, 

 Corbula, and other shells, together with an Urchin belonging to the genus Brissus. 



X. The Second Gryphaa or Exogyra Group. — The lower part of this group consists of 



