82 Reviews — Yorkshire Type Ammonites. 



II. — The Association of Facetted Pebbles with Glacial Deposits. 

 By J. W. Jackson. Mem. and Proc. Manchester Lit. and Phil. 

 Soc, vol. lxii, No. 9. 



FACETTED and wind-worn pebbles are described from Lancashire 

 and Cheshire, and it is shown that they are of post-Glacial and 

 pre-Neolithic age. The author considers, in accordance with the 

 conclusion previously reached by Dr. Bather, that such pebbles do 

 not in themselves provide evidence of arid or steppe conditions. 

 At the close of glaciation in any country the land must have been 

 bare, strewn with pebbles associated with an abundance of sand, and 

 exposed to winds. Remembering that many of the pebbles had been 

 already fractured by frost, the conditions were thus favourable for 

 the development of facetted pebbles by the action of a natural sand- 

 blast. It is suggested that an intimate connexion exists between the 

 period of wind-erosion and the deposition of the seolian sand of 

 Shirdley Hill. 



III. — Yorkshire Type Ammonites. Edited by S. S. Buckman. 

 Photographs mainly by J. W. Tdtcher. Part xvii, pp. xiii, xiv, 

 8 plates and descriptions JSTos. 117-119. London: Wesley. 1918. 



THIS part is remarkable for the number of new names, not always 

 of classic elegance. Fimbrilytoceras is for " the series to which 

 Am. fimbriatus, Sowerby, belongs", since A. fimbriatus d'Orb., is 

 the genotype of Lytoceras. The two genera are contrasted. " Owing 

 to the regulations of the Oxford University Museum, photographs of " 

 the holotype of A. fimbriatus Sow. "could not be obtained" — a 

 statement that needs explanation. Pseudocadoceras is based on one 

 syntype of A. longevous Bean, while the other syntype, now the 

 lectotype, becomes the genotype of Longceviceras. JSboraciceras (an 

 uneasy name) is founded for A. dissimilis Brown, here refigured; 

 Prorsiceras for A. gregarius Bean-Leckenby, also refigured; and 

 Vertumniceras for A. vertumnus Leckenby, as mentioned in the 

 preceding Part. These last four are Cadoceratidse. A. crassus 

 Young & Bird, is refigured and referred to Cceloceras. Plates are 

 also given of Bifericeras parvum (S. Buckman, 1904, sub Microceras), 

 B. nudicosta (Quenst.), and Beanieeras rotundum nov. (based on 

 Ammonites centauries J. Buckman) ; but these are not from Yorkshire. 

 The descriptions convey a large amount of information to those who 

 will trouble to interpret them ; the clear photographs speak for 

 themselves. 



IV. — The Water. Supply op Essex. By "W. Whitaker and J. C. 

 Thresh. Mem. Geol. Survey, pp. 510 and 4 maps. 1916. 

 Price 155. 



THE memoir contains, in addition to well-records, chapters 

 dealing with the Avater-bearing beds, rainfall, chemistry of 

 Essex waters with analyses, contamination and risk thereof, supplies 

 from springs, wells, and borings. 



It is accompanied by an extensive bibliography and by maps 

 showing (1) the underground water-level in the Chalk around the 

 head-waters of the Stort and Cam, (2) the amount of chlorine in 

 deep-well waters, (3) wells giving alkaline waters, (4) the rainfall. 



