May 21, 1915] 



SCIENCE 



765 



the temporal and antorbital fenestrse of reptiles 

 are reinforced by much additional evidence. 



3. The inferred conditions of the jaw mus- 

 culature of Cynognathus are entirely in har- 

 mony with the yiews (a) that in the mammal 

 the back part of the reptilian jaw became 

 transformed into the accessory auditory ossi- 

 cles; (&) that the basal portion of the mam- 

 malian alisphenoid is homologous with the 

 reptilian pterygoid as suggested by Watson,^ 

 while the ascending portion seems to have been 

 derived from the epipterygoid, as held by 

 Broom and Watson. 



4. In the transitional pro-mammals the rep- 

 tilian pterygoid muscles pterygoideus ante- 

 rior) became greatly reduced in correlation 

 with the reduction of the elements behind the 

 dentary; a possible vestige of these muscles 

 may be the tensor tympani muscle, which runs 

 from the basicranial region to the handle of 

 the malleus. The mammalian internal and 

 external pterygoid muscles are only partly 

 homologous with those of existing reptiles and 

 represent slips of the eapiti-mandibularis 

 mass, developed as the new joint between den- 

 tary and squamosal became established. The 

 loss of the descending flange of the reptilian 

 pterygoid, the secondary separation of the 

 pterygoids along the mid-line and the trans- 

 formation of the reptilian transpalatine into 

 the true mammalian pterygoid (as held by 

 Watson) all become more intelligible when 

 considered in connection with the above-de- 

 scribed changes in the musculature. 



5. As a working hypothesis it is assumed 

 that the transformation of certain elements in 

 the temporal and occipital regions of early 

 Tetrapoda was partly conditioned by the 

 stresses induced upon the skull roof by the jaw 

 and neck muscles. Comparison with lizards, 

 Sphenodon, etc., clearly indicates that the 

 prolongation of the parietal into a postero- 

 external process joining the true squamosal 

 was correlated with the squeezing effect of 

 the eapiti-mandibularis and depressor mandi- 

 bulse muscles. This may also be responsible 

 for the appression and coalescence of the supe- 



iAnn. Mag. Nat. Hist. (8), Vol. VIII., Sept., 

 1911, pp. 322-23. 



rior and lateral temporal elements (supra- 

 temporal and squamosal), in the early reptiles. 

 The shifting of the post-parietals (dermo- 

 supraoccipitals) and tabularia from the dorsal 

 to the posterior aspect of the occiput was no 

 doubt influenced also by the forward growth 

 of the neck muscles upon the occiput. 



W. K. Gregory, 

 L. A. Adams 

 American Museum op Natural Histobt 



TEE AMEBIC AN ASSOCIATION FOB THE 



ADVANCEMENT OF SCIENCE 

 SECTION D— MECHANICAL SCIENCE AND 

 ENGINEEBING 

 The first session was held in the morning of 

 Wednesday, December 30, in the engineering build- 

 ing, Vice-president Frederick W. Taylor and Dr. 

 Charles S. Howe in the chair, with an attendance 

 of about 130. It was announced that the sectional 

 committee had recommended for election to the 

 general committee for the office of Vice-president, 

 Dr. Bion J. Arnold, of Chicago. The following 

 officers were elected by the section: 



Member of Council — ^Dr. Eudolph Hering, of 

 New York City. 



Member of General Committee — Morris L. Cooke, 

 of Philadelphia. 



Member of Sectional Committee — ^Dr. Charles S. 

 Howe, of the Case School of Applied Science. 

 The progi-am of the session was as follows: 

 Principles of Scientific Management: Dr. Fred- 

 erick W. Tatlor. 

 Which is to Control Public Worhs — a Board or a 



Single Head?: Morris L. Cooke. 

 The Improvement and Enlargement of Transpor- 

 tation Facilities: George S. Webster. 

 A Study in Cleaning Philadelphia's City Hall: 

 William H. Ball. 



Every city, town and hamlet which owns a pub- 

 lic building of any kind is confronted with the 

 problem of efficient and economical cleaning. 

 Public buildings are constantly growing in size 

 and it is becoming more and more possible to 

 handle the problems of their maintenance and 

 operation on a technical basis. The fact that 

 after what must be admitted to have been a 

 crude study, extending over only a few months, we 

 were able to effect economies amounting to over 

 $30,000 a year, or $100 a day, in the cleaning of 

 one public building, shows the possibilities. Ac- 

 cording to technical and other literature the clean- 

 ing of public buildings has been given very little 



