282 Reviews — Artesian Boring, British Guiana. 



neighbourhood that an even later date is possible. In this connexion 

 it is interesting to note that the affinities of the known fauna of the 

 Carrizo formation are definitely with that of the Gulf of California, 

 and have no apparent relation to that of the Pacific region — an 

 indication that the Peninsular Mountains then, as now, formed 

 a continuous barrier between the two districts. 



The Carrizo Series is divided into two sections, from the lower of 

 which all the Echiuoids have been exclusively collected. The upper 

 part of the series seems to have been formed under brackish conditions, 

 during the gradual silting-up of the Gulf. The lower series exhibits 

 two facies — a littoral zone of reddish conglomerate and arkose, and 

 an outer zone, reaching as much as 50 fathoms in depth, represented 

 by finer sediments. It is interesting to find that the species of 

 Echinoids that predominate in one type of deposit are rare or absent 

 in the other, although representatives of the same genera are 

 abundant in both. 



One species of Hipponoe, three of Clypeaster, one of Encope, and an 

 indeterminable specimen of Cidaris are described. All but one of 

 the species are new, but the impression left by a perusal of the text 

 and a study of the plates is that their chief claim to novelty lies in 

 their fossil condition. There seems to be something akin to the point 

 of view of a century ago in the specific separation of recent and fossil 

 types in spite of their resemblances. In every case but one the 

 species described are admitted to differ from the existing forms of the 

 district in mere details of size and proportion. That they are 

 ancestral to the species of the present day seems clear, but it 

 seems doubtful whether, in the majority of cases, their ancestral 

 characters render them sufficiently distinct for more than varietal 

 separation. 



Perhaps the most interesting of the forms described is JEneope 

 tenuis, which is practically identical with the recent E. californica, 

 but has the radial lunules of the latter species represented by 

 the primitive condition of marginal notches. Clypeaster carrizoensis, the 

 species whose living representative is unknown, appears from the 

 figure to be more nearly related to Laganum than to Clypeaster. 



It is greatly to be hoped that further researches may be made into 

 the fauna of the Carrizo formation, and that thereby the history of 

 the peculiar and teeming fauna of the Gulf of California may be more 

 fully written. In the meantime this paper should be of value as 

 showing the possibilities underlying such research in the solution of 

 problems of both biological and geographical interest. 



H. L. H. 



IV. — Geology of the Strata, traversed sr the D'tTKBAN Aetesian- 

 Well Borikg, 1913. By Professor J. B. Harrison, M.A., C.M.G. 

 pp. 18. British Guiana Combined Court, Annual Session, 1914. 



PREVIOUS well-borings in British Guiana appear to have tapped 

 water derived from beds of sand at less than 200 feet below the 

 surface. These sands wei'e thought to be stratified beds, but they are 

 now shown to be more or less lenticular masses of wind-blown sand : 



