Maech 16, 1900.] 



SCIENCE. 



427 



first, and the uuion of quadrate to cranium by 

 ascending and otic processes is exactly as in 

 urodele amphibia. The hyomandibular appears 

 later than the body of the hyoid arch, and has 

 no connection with the jaws. The trabec- 

 ulse are widely separated, leaving a large ven- 

 tral fontanelle, also an amphibian character. 

 The palatopterygoid bar is almost entirely sup- 

 pressed. The one character which is entirely 

 fishlike is the otic capsule. 



A summary of Mr. Sumner's paper is as fol- 

 lows: 



I. The generally accepted account of the gas- 

 trulation in the Teleosts as proposed first by 

 Gotte, was shown to be incomplete, in so far 

 as it failed to give a true account of the hy- 

 poblast. 



II. A view of Kupfer's vesicle was main- 

 tained, closely similar to that proposed by the 

 great morphologist after whom the structure 

 has been named. 



III. The present author has arrived, on purely 

 morphological grounds,ata view of concrescence 

 identical with that proposed by Kopsch on the 

 basis of the latest experimental work. 



Dr. George S. Huntington's paper dealt spe- 

 cifically with the retro-clavicular group of su- 

 pernumerary muscles, for the purpose of de- 

 termining their mutual relationship and common 

 derivation. The new muscle, here described 

 for the first time, completes a series of retro- 

 clavicular aberrant muscles which represent 

 different stages in migration and recession of the 

 typical mammalian M-sterno-choudro-scapu- 

 laris. The members of this group appear there- 

 fore as myo-typical reversions representing per- 

 sistent portions of this muscular plane, with 

 secondary skeletal attachments depending upon 

 the degree of recession. 



Francis E. Lloyd, 



Secretary. 



SECTION OF GEOLOGY AND MINERALOGY. 



At the meeting of February 19, 1900, with 

 Mr. G. F. Kunz in the chair, there were sixteen 

 persons present. 



Professor R. E. Dodge announced the death 

 of Dr. Hans Bruno Geinitz on December 30, 

 1899. He also stated that Professor J. J. Ste- 

 venson had been appointed by the Council of the 



Academy as delegate to the coming meeting of 

 the International Geological Congress, and that 

 the Council had voted to become a subscriber 

 to the fund of that Congress. 



The Chairman briefly discussed the character 

 and work of Dr. Geinitz, and, on motion, Pro- 

 fessor Stevenson was appointed a committee 

 to prepare a minute on this great loss to the 

 Academy and to science. 



The following specimens were exhibited by 

 the Chairman : 



Corundum from Raglan Township, Ontario, 

 Canada. 



Variously colored sapphires from a new lo- 

 cality. Clear Creek, Granite county, Montana. 



Corundum from a serpentine dike at a new 

 locality. Corundum Hill, Plumas county, Cali- 

 fornia. 



The regular paper of the evening was then 

 read by Dr. Henry S. Washington, illustrated 

 by diagrams and specimens : 



' The Igneous Complex of Magnet Cove, 

 Arkansas.' The structure of the complex is 

 described and, from the evidence of the form of 

 the area, the relations to the surrounding shales, 

 the presence of an overlying zone of metamor- 

 phosed rock, the arrangement of, and the serial 

 petrographical and chemical characters of the 

 main rock types, with other minor points, the 

 conclusion is drawn that the igneous comi)lex 

 is probably a laccolith, and certainly a unit ; 

 and that the main component abyssal rocks are 

 not due to successive injections, as was sug- 

 gested by J. F. Williams, but are the result of a 

 differentiation in situ of the mass of magna. 



The main rock types are described, some 

 new analyses being given, and they are shown 

 to form a regularly graded series of interesting 

 rocks, ranging from basic jacupirangite, through 

 biotite-ijolite, typical ijolite, shonkinitic syenite 

 and leucitesyenite, to foyaite. This serial, 

 and common genetic character is shown both 

 mineralogically and chemically. It is probable 

 that the dikes of tinguaite and nepheline- 

 porphyry are aschistic, while those of monchi- 

 quitic rocks are diaschistic. 



The arrangement of the abyssal rocks is 

 shown to differ radically from most other cases 

 of differentiated laccolithic masses and dikes, 

 in that there is progressive increase in acidity 



