500 Scientific Intelligence. 



» 

 varieties, which are arranged in six subgeneric groups. The genus 

 in its early development includes species principally of the type 

 of D. Hausmanni. Variation takes place mainly in the lobes 

 and furrows of the glabella and in the ornamentation, of the mar- 

 gins of the cephalon and pygidium. During the period of the 

 deposition of the Helderberg series the culmination of develop- 

 ment was reached, and many deviations from the original simple 

 type were introduced. The ornamental and defensive armature 

 became extravagantly developed, and several species reached a 

 large size. One form, D. myrmecophorus, is estimated from 

 a careful restoration based on a large pygidium, to have had a 

 length of 398 mm or 16 inches. The genus Lichas exhibits a similar 

 development and variety of form. It includes the largest and 

 most remarkable of Devonian tr-ilobites, the Lichas {Terataspis) 

 grandis Hall, with individuals reaching a length of nearly two 

 feet and bearing numerous spines and tubercles. The majority 

 of the species of trilobites discussed in this volume are found in 

 the Lower Devonian, and all the genera made their appearance 

 in earlier Palaeozoic time. 



To many students the portion of the volume relating to species 

 not trilobitic will have the greatest interest on account of the 

 rarity and diversity of the material and its relations with exist- 

 ing forms. This non-trilobitic crustacean fauna holds an import- 

 ant place in the middle and upper Devonian, and but three or 

 four of the nineteen genera here noticed, were continued from 

 earlier faunas. 



The supplementary matter is in continuation of vol. v, pt. II, 

 published in 1879, and relates to the classes Pteropoda, Annelida 

 and Cephalopoda. A specimen borrowed from the TJ. S. Geol. 

 Survey, through C. D. Walcott, and referred by him to Proetus 

 marginalis Con. (Walcott, Monogr. U. S. G-eol. Surv., vol. viii, 

 Pal, Eureka Dist.,p. 210, 1884), is redescribed as Proetus Nevadm 

 Hall. This method of treating borrowed type specimens will 

 not meet with general approval. c. e. beechee. 



4. Geology of Minnesota, Bidletin No. 2, 1887. Preliminary 

 description of the peridotytes, gabbros, diabases and andesytes of 

 Minnesota ; by M. E. Wadsworth. 160 pp. 8vo, with 12 col- 

 ored plates of rock-sections. — This Report discusses critically the 

 characteristics of the many rocks studied, their interior changes 

 and other points of petrological interest. It is preliminary to a 

 final report on the Minnesota rocks. 



5. Building- Stone in the State of New York ; by J. C. 

 Smock. — Bulletin of the New York State Museum of Natural 

 History, No. 3, March, 1888. Albany, 1888. 



6. Carboniferous Trilobites. — Lieut. A. W. Vogdes has a paper 

 on American Carboniferous trilobites in the Annals of the N. Y. 

 Acad. Sci., Febr., 1888, reviewing the synonymy and the charac- 

 ter of the species, adding notes, and giving figures of 19 species. 



7. Les Dislocations de Vecorce terrestre: Essai de Definition 

 et de Nomenclature par Emm. de Mabgaeie, a Paris, et Dr. Albeet 



