570 



SCIENCE 



[N. S. Vol. XLI. No. 1059 



group of organisms contributes to the marine sedi- 

 ments, and therefore to the formation of marine 

 limestones and especially to their magnesian and 

 phosphatie varieties. The work is practically com- 

 plete as regards the true corals, the mollusks, the 

 brachiopods and the eehinoderms. The inorganic 

 constituents of the corals and mollusks are mainly 

 calcium carbonate, with insignificant impurities. 

 The eehinoderms are all more or less magnesian, 

 their skeletons containing from 6 to 14 per cent, of 

 magnesium carbonate. The brachiopods fall into 

 two groups, the shells of one group being mainly 

 calcium carbonate with little organic matter; while 

 those of the other group are essentially calcium 

 phosphate with much organic matter. Work is 

 yet to be done on the foraminifera, the coralline 

 hydrozoans, the bryozoans, sponges and crustaceans. 

 Some of the results so far obtained are novel, 

 others merely confirm the older recorded observa- 

 tions. 



Chaelbs a. Davis: On the Fossil Algm of the 

 Petroleum-yielding Shales of the Green Siver 

 Formation. 



The Green Kiver shales of Eocene age are known 

 from northwestern Colorado, west into Utah and 

 north into Wyoming. In places they are more 

 than 3,000 feet thick. They are usually hard, 

 tough, compact and fine-grained and brown in 

 color, but weather to light gray or whitish. Cer- 

 tain beds are highly carbonaceous, burn freely and 

 appear like lignite. Freshly broken surfaces give 

 off a bituminous odor but never appear oily; when 

 heated in closed retorts, petroleum passes off among 

 the distillates. 



By special treatment this shale has been sec- 

 tioned to any desired thinness with a microtome. 

 Microscopic examination of such sections from 

 samples yielding abundant petroleum on distilla- 

 tion, shows the shale to be composed largely of or- 

 ganic matter, chiefly of vegetable origin, as well- 

 preserved plant remains are common. 



The most conspicuous plants observed are micro- 

 scopic algae, which are very numerous in the slides 

 so far studied. 



The discovery of a very considerable algal flora 

 in this great and but slightly altered series of 

 petroleum-yielding shales is of especial interest be- 

 cause of the light it may throw on the origin of 

 petroleum and related compounds. 



(A few lantern slides from microphotographs of 

 fossil algse from the shales will be shown.) 

 J. Walter Fewkes: Pictures on Prehistoric Pot- 

 tery from the Mimhres Valley in New Mexico, 

 and their Belation to those of Casas Grandes. 



The unexpected discovery near Doming, New 

 Mexico, of an exceptionally large number of vessels, 

 made of earthenware, decorated with paintings of 

 mythic animals and men, has led to an enlarged 

 knowledge of the prehistoric culture of our south- 

 west. These pictures, unknown a year ago, have 

 been found in great abundance, and are highly 

 characteristic. Those representing men engaged in 

 various occupations are particularly valuable in the 

 light they throw on ancient manners and customs. 

 These pictures were painted by a people ante- 

 dating the nomads found in the Mimbres Valley by 

 the first white visitors, and who disappeared be- 

 fore the beginning of the historic epoch. The pic- 

 tures have archaic characteristics that point to a 

 remote antiquity as compared to that on modern 

 pueblo pottery. 



The cause of the disappearance of this culture 

 from the Mimbres Valley can be traced to local 

 influences rather than to widespread modifications 

 of climate. One of the important local causes of 

 the abandonment of the prehistoric settlements 

 when they were found, was a change in the course 

 of the river. 



The geographical isolation of the Mimbres 

 Valley has played an important r51e in developing 

 the peculiar culture these pictures express, while 

 its north and south extension has facilitated inter- 

 changes of cultures leading to far-reaching resem- 

 blances in these directions. 



C. B. Davenport: Inheritance of Huntington's 

 Chorea. 



Huntington 's chorea is a name applied to a group 

 of symptoms first brought together as an entity by 

 Dr. George S. Huntington. The traits involved are 

 four: (1) persistent tremors over a less or greater 

 part of the body; (2) their onset in middle or late 

 life; (3) their progressive nature, and (4) a pro- 

 gressive mental deterioration. Analysis of many 

 chorea-bearing fraternities shows that this sup- 

 posed neuropathic entity is really only a syndrome 

 inasmuch as, in the choreic families, mental deteri- 

 oration may appear without tremors, the tremors 

 may progress without mental symptoms, the mental 

 symptoms may not progress and the onset of the 

 disease may be in early life. Indeed, an analysis of 

 families reveals the presence of biotypes char- 

 acterized by specific forms of choreic involvement 

 and progression. In the inheritance of the ele- 

 ments of the syndrome the choreic movements are 

 clearly a dominant trait; some of the elements of 

 the mental condition (which is usually allied to 

 manic-depressive insanity) are also dominant. 

 The law of anticipation in successive generations 



