Geology and Mineralogy. 235 



10. Elemente der Palaontologie bearbeitet von Dr. Gustav 

 Steinmann, Ord. Prof. Geol. Min. Univ. Freiburg, i. Br., unter 

 mitwirkung von Dr. L. Doderlein, Dir. nat-hist. Mus. Strass- 

 burg. 1 Halfte (Bogen 1-21). PJvertebrata, Protozoa, Gastro- 

 poda. 336 pp. 8vo, with 386 woodcuts. Leipzig, 1888. (Wil- 

 li elm Engelmann). — This general treatise on Zoological and 

 Botanical Paleontology describes the groups and genera and illus- 

 trates them with many figures representing species and details 

 of structure. It also gives tables showing the geological distri- 

 bution of groups. The figures are well chosen, and beautifully 

 engraved. The work will be found of great value by students 

 in Geology and Paleontology. The second half, treating of the 

 Invertebrates, the Vertebrates and Plants, is promised in the 

 course of the current year. 



11. Die Stamme der Thierreichs von Dr. Neumayr, Wir- 

 bellose Thiere. Erster Band., 603 pp. with 192 text-figures. 

 Vienna and Prague, 1889. (F. Tempsky). — Dr. Neumayr treats, 

 in his valuable work, of the successional relations of species in 

 the animal kingdom, in illustration of the subject of evolution. 

 He describes the various groups in zoological order, illustrates 

 their structure and forms by figures, and dwells at length on all 

 the zoological and geological facts that have a bearing on the 

 question of derivation. This first volume of 600 pages carries 

 the work to the close of the Molluscoids (Brachiopods). 



12. Fossil Cockroaches. — S. H. Scudder has described seven 

 new species of Etoblattina, from the Barren Coal-measures of 

 Richmond, Ohio.— Proc. B. S. JV. H., vol. xxiv, 45, Nov., 1888. 



13. Visual area in the Trilobite, Phacops rana ; by J. M. 

 Clarke. — This excellent paper is the result of a thorough study, 

 as far as material allowed, of the composition and structure of the 

 different parts of the eyes in this trilobite, and the relation as 

 regards the eye between the Phacopidge and other trilobites. — 

 Joum. Morphol., ii, Nov., 1888, Boston. 



14. Mineralogieal Notes • by E. F. Ayres (communicated). 

 Thenardite. — Some specimens of thenardite recently obtained 

 from Borax Lake, San Bernardino Co., California, exhibit a 

 method of twinning that has apparently not been described. 

 The crystals average about an inch in length and are tabular or 

 short prismatic in habit. They show the unit prism, m(l 10), basal 

 plane c(001), the unit pyramid o(lll), and a low macrodome, 

 probably £(106) and probably the pinacoid a(100) ; the oscillations 

 of the form t give rise to a flat striated surface often replac- 

 ing c. The crystals are rough and allow only of approximate 

 measurements with a contact goniometer ; these are given here 

 with the angles calculated from the axial ratio of Barwald,* 

 The position taken is that which makes the prism of nearly 60° 

 vertical. 



* Groth's Zeitschr., vi, 36. 



