142 



SCIENCE. 



[Vol.. II., No. 26. 



rite and nepheline-basalt, while porpliyrytufE occu- 

 pies a portion of the Kesselberg area. The granilite is 

 a crystalline granular mixture of felspar, quartz, and 

 biotite, and is regarded as a typical rock of its Icind. 

 The quartz-porphyry has a compact, red groundmass 

 porphyritically enclosing quartz and felspar, also 

 biotite, apatite, and magnetite. The mica-syenite- 

 porphyry has a compact, deep reddish-brown ground- 

 mass, holding biotite and felspar, as well as some 

 quartz, apatite, and zircon. 



The neplieline-basalt sliows a compact, greenisli- 

 blacli groundmass, holding crystals and grains of a 

 fresh, nearly colorless olivine. The groundmass is 

 composed of a mixture of augite, little olivine crys- 

 tals, and magnetite grains cemented by a colorless 

 mass of nephelite and glass. Some reddish-browu 

 biotite was observed, while apatite in little needles 

 occurs abundantly. The paper is accompanied by a 

 plate and map, while tlie classification followed is 

 that of Prof. Kosenbusch of Heidelberg, witli whom 

 Dr. Williams studied. This classification of eruptive 

 rocks is now the prevailing one in Germany, and, on 

 account of the number of Rosenbusch's students con- 

 nected with the U.S. geological survey and with other 

 institutions, will be soon generally used in Amer- 

 ica. — {Neues jahrb. min., beil., 1883, ii.) M. E. w. 



[149 

 GEOGBAPHY. 

 (Arctic.) 



Danish expeditions in Greenland in 1883. — 

 Dr. Rinlv, who is now resident in Kristiania, gives 

 some details as to the proposed work for this sea- 

 son. Lieut. G. Holm, assisted by. Lieut. Garde, 

 geologist Knutsen, botanist Eberlin (who also acts as 

 surgeon), and a number of Greenlanders, will under- 

 take the exploration of tlie eastern coast of Green- 

 land in imiiaks, in the narrow strip of water between 

 the great stream of drift-ice and the shore, where 

 these boats may be able to accomplish much not 

 practicable for a vessel. They will endeavor to pass 

 the northern extreme reached by Graah, 1828-30, and 

 to penetrate to tlie interior by some of the deep fiords, 

 thus obtaining some idea of tlie region between them 

 and the western coast. The other expedition will 

 endeavor to map the unexplored portion of the west- 

 ern coast between 67° and 70° N. lat., and will be 

 commanded by Lieut. Hammer, assisted by Sylow 

 as geologist, and naval Lieut. Larsen. Notice has 

 already been taken of the arrival of these parties in 

 Greenland. — {Naturen, Mai, 1883. ) w. h. d. [150 

 {SmitJi America.) 



The death of Crevaux. — The details of the de- 

 struction of this gallant explorer and his party have 

 been obtained from a native interpreter, who was 

 made captive at tiie time, but finally escaped across 

 the desert to Anl;aroinga. The party had arrived at 

 a spot on the riglit bank of the Pilcomayo, five leagues 

 above the Rio Tigre, where there is a village of Toba 

 Indians called Cuvarocai. After having been assured 

 of a peaceful welcome, the doctor began to distribute 

 presents to the natives, who, at the advice of their 

 chief, rendered covetous by the sight of the valuables 

 in the hands of the party, fell suddenly upon the ex- 



plorers, and killed those on the shore. Those still in 

 the boats attempted to escape by swimming, and 

 were pursued, and several of them killed in the water. 

 Only two, Haurat and Blanco, being good swimmers, 

 succeeded in reaching the opposite shore, and hiding 

 themselves in the forest. Nothing has been heard of 

 them since. The interpreter was carried off as a 

 prisoner. The bodies were thrown into the water 

 or left where they fell, except that of Dr. Crevaux, 

 wliich was carried to a neighboring village, where 

 for thirty-si.x hours the Tobas sang and performed 

 incantations around it, after which it was conveyed 

 to a spot near to and visible from the huts. The 

 Argentine government has sent Col. Sol with two 

 hundred men up the Pilcomayo to punish the assas- 

 sins, while the geographical society of Buenos Ayres 

 has sent one of its number to search for the two 

 survivors, and report on the whole subject. — w. H. D. 



[151 



Crevaux's voyages in Guiana. — Henri Froide- 

 vaux summarizes previous investigations of the rivers 

 of Guiana, and narrates the advances due to Crevaux. 

 He notes that the indigenous population of Guiana 

 is visibly decreasing, and states that Crevaux believed, 

 that, judging by the abundance of village sites and 

 relics on the river-banks now absolutely depopulated, 

 there was formerly an abundant population. — (Rev. 

 I?e0!7>-., May, 1883.) w. H. D. 152 



Notes. — Dr. Giissfeldt has made interesting trig- 

 onometrical surveys in the Cordillera, together with 

 observations on glaciers. He will soon take up the 



region about Aconcagua. The English brothers 



Haspold, with the warmest approbation of the gov- 

 ernment of the republic, have undertaken a very exact 

 geological, mineralogical, and natural history survey 

 of the different Argentine states. — (Mitt, geogr. ges, 

 Wien, xxvi. no. v.) w. H. D. [153 



(Africa.) 



Number of JeTws in Africa. — According to the 

 estimate of Brunialti, the Jews in Africa number 

 450,000. Gerhard Rohlfs criticises this as much too 

 high, and, by reviewing the estimates of population 

 in all parts of the continent, concludes that 220,000 

 is much nearer the truth. — (Peterm. geogr. mitth., 

 1883,211.) w. M. D. [154 



The coast-line of Tunis. — In his description of 

 the Mediterranean lands, Th. Fischer has included 

 Tunis in the area of rising coasts about Sicily, 

 Sardinia, and south-eastern France. The correctness 

 of tliis is questioned by Dr. J. Partsch of Breslau, 

 who presents a considerable mass of evidence to show 

 that tlie Tunisian shores have not changed their 

 altitude in the historic period, although their out- 

 line has varied distinctly at certain points by delta 

 growth. The river Medjerda (the ancient Bagradas) 

 has shifted its mouth several miles to the north, and 

 built out its delta into the Gulf of Tunis; and this 

 in combination with the wind-action, by whicli sand 

 has been blown inland from the shore, has added 

 nearly one hundred square miles of lowland outside 

 of the coast-line of the third century before Christ. 

 Former lines of river-flow are distinctly visible at 



