Geology. 161 



the fossil forms [three] which are only modifications of the names 

 of the living forms which they so closely resemble." In the 

 Tertiary all connecting forms are absent, but the author explains 

 that the Cenozoic species thus far found are plain types such as 

 are now obtained only in still waters or lakes. " The more diverse 

 and ornamental forms of living Uniones occupy fluviatile, or 

 other running or moving waters. None of the deposits contain- 

 ing the Tertiary Uniones referred to gives any inherent evidence 

 of having been formed in fluviatile or estuarine waters." 



" Fresh-water gill-bearing faunas have as certainly descended 

 genetically through successive geological ages to the present time 

 as have marine faunas. . . . There has never been any intermission 

 of such continuity because the fresh-water supply has never 

 failed, and because, as a rule, rivers have been among the most 

 persistent of the earth's surface features." c. s. 



9. The Thalattosauria, a group of marine reptiles from the 

 Triassic of California ; by John C. Merriam. Mem. California 

 Acad. Sci., V, 1905, pp. 1-52, pis. 1-8. — During the past three 

 years the Geological Department of the University of California 

 has been collecting the remains of the marine reptiles from the 

 Upper Triassic of Shasta county. From the fact that both are 

 black, the material is very difficult to clear from the matrix, the 

 latter being a shaly limestone. 



This memoir describes in detail the skeletal structure of the 

 Thalattosauridse, comprising the genera Thalattosaurus (T. alex- 

 andrai, T. shastensis sp. nov., T. perrini sp. nov.) and Nectosau- 

 rus gen. nov. (N~. halius sp. nov.). The pen and ink illustrations 

 are good. 



"The Thalattosaurs represent an early adaptation to marine 

 conditions of that division of the Reptilia which has persisted in 

 measurably primitive form in the Rhynchocephalia. During the 

 early history of that group it gave rise to a numerous company 

 of forms taking quite divergent paths in their evolution. Of the 

 older orders on\j the Proganosauria were aquatic. They appear, 

 however, to have heen limited to fresh water. The Thalattosaurs 

 are evidently the marine representatives of this great rhyncho- 

 cephalian or diaptosaurian group." c. s. 



10. The Geology of JOittleton, JVew Hampshire ; by C. H. 

 Hitchcock. Pp. 38, 2 plates and map. Reprinted from History 

 of Littleton, 1905. — This paper brings together all that is known 

 in regard to the geology about Littleton, including the recently 

 published article by Hitchcock (Bulletin Geol. Soc. America). 

 The strata present are referred to the Quaternary, Helderberg, 

 Silurian, Lower Silurian or Cambrian, and eruptives. In an appen- 

 dix, Mr. Avery E. Lambert describes a new trilobite, Dalmanites 

 hmatus, with notes on other fossils from the Littleton area. c. s. 



11. Vorschule der Geologie ; von Johannes Walther. Pp. 

 144, and 98 original text figures. Jena, 1905. — This very inter- 

 estingly written, simply stated, and well printed little book on 

 elementary geology is intended for beginners in geology. They 



Am. Jour. Sci. — Fourth Series, Yol. XX, No. 116.— August, 1905. 

 11 



