370 



Notices of Memoirs. 



27. Cticconeis placentula, Ehr. 



28. Tar. lineata, Grun. 



29. Achuanthidium lanceolaticm, Breb., 



var. diibia, V. H. 



30. Hpithemia ffibba, Kutz. 



31. Epithemia gihba, var. parallela, 



V. H. 



32. var. clavata ( = E. clavata, 



J.L.B.,MS.inCoU.E.M.S.). 



33. var. ventricosa, Kutz. 



34. E. zebra, Kutz. 



35. var. proboscidea, Kutz. 



36. ^. sorex, Kutz. 



37. E. gibberida, Kutz. 



38. Ennotia incisa, Greg. 



39. Fragilaria mutahilis, Grun. 



40. var. intermedia, Grun. 



41. F. constriiens, Grun. 



42. var. venter, Grun. 



43. F. virescens, Ealfa. 



44. Synedra splendens, Kutz. 



45. 8. ulna, Ehr. 



46. S. oxyrhynchus. Smith. 



47. var. nova, var. mesolepta. 



48. Odontidium mesodon, Kutz. 



49. Surirella linearis. Smith. 



50. 8. Smithii, Ealfs (a large form of it) . 



51. JVitzschia tenuis, Smith. 



52. I^. amphibia, Grun. 



53. Stephanodisciis astrcea, Grun. 



54. var. spinulosa, Grun. 



55. Cyclotella Kutzingiana, Thwaites. 



56. C. opercnlata, Kutz. 



67. Melosira granulata, \ Tj^gge three 



Ealis. r • , 



" M. crenulata, Kutz. ( ^^J JJj^^^^ 



M. tenuis, Kutz. 

 M. distans, Kutz. 



My deepest thanks are due to Mr. G. T. Prior, of the British. 

 Museum (Natural History), to Dr. Wynne, of the Eoyal College 

 of Science, and to Mr. Thomas Comber, — to Mr. Prior for his 

 kindness in examining and naming the rock specimens, and in 

 supplying the petrographical descriptions ; to Dr. Wynne for 

 chemical analyses of water and rocks, and for the deep interest 

 he has shown in the matter ; and to Mr. Comber for his exhaustive 

 examination of the diatomaceous earth. 



isTOTiGES oip DvnzEnvcoiiE^!; 



I. — The Geological History of the Eivees of East Yokkshirk, 

 being the Sedgwick Prize Essay for the year 1900. By F. K. 

 Cowper Eeed. 8vo. London (Clay), 1901, 4s. nett. — The selection 

 of the dependence of the watercourses of a country upon its 

 geological structure as the subject of the Sedgwick Essay for 1900, 

 gave Mr. Eeed an opportunitj^ of turning out a piece of work on 

 a subject which has not received that attention in this country it 

 has deserved. The district chosen by the author for his investigations 

 has been carefully surveyed and mapped, and due acknowledgment 

 has been made of the work of the Officers of the Geological Survey, 

 and particularly of that of Mr. Fox-Strangways. 



Mr. Eeed divides his essay into five parts : — (1) General characters 

 of East Yorkshire ; (2) Geological structure ; (3) Physical history ; 



(4) The present rivers and their relations to the geological structure ; 



(5) The history of the relations of the rivers to the geological 

 structure. His observations are illustrated by maps. 



Mr. Eeed draws the following conclusions : — " By the preceding 

 examination of the geological and physical evidence we have traced 

 the general outlines of the evolution of the present drainage-system 

 of East Yorkshire through several successive stages, and we find 

 that its history is intimately bound up with that of the whole of 

 Eastern England since Paleozoic times. There are local details 



