March 31, 1911] 



SCIENCE 



509 



saurs and microsaurs do not carry us very far 

 back toward any known type of fish fin. In these 

 orders the cylindrical shafts of the long bones, 

 with cartilaginous ends, the cartilaginous carpus 

 and tarsus, the weak shoulder girdle and pelvis 

 suggest a secondary adaptation to aquatic habits. 

 From the work of Thaeher, Goodrich, Dean, R. 

 C. Osburn and others, it seems probable that the 

 paired fins of fishes, like the median fins, have 

 evolved from wide-based fins with serially arranged 

 basal and radial cartilages. After the formation 

 of the primary shoulder girdle and pelvis and of 

 the pro-, meso- and metapterygia by fusion and 

 growth of the basals, the various types of paired 

 fins seen in plagiostomes, chimaaroids, pleuracanths, 

 dipnoans, crossopterygians and actinopterygians 

 seem to have arisen in each case through the pro- 

 trusion of the basal cartilages, differential growth 

 ^nd shifting of the radials, and in some cases 

 (e. g., pleuracanths, crossopterygians, dipnoans) 

 also through the extension of the radials around 

 to the post-axial side of the metapterygial axis. 

 If the Amphibia have descended from forerunners 

 of teleostomous and dipnoan fishes (as seemed 

 likely) then it was entirely probable that their 

 paired fins had been transformed into limbs 

 through the extreme protrusion of the proximal 

 cartilages, differential growth and regrouping of 

 the more distal cartilages, reduction of the dermal 

 rays. This structural change may well have been 

 in large part effected before the air-breathing 

 proto-amphibians had left the water, owing to 

 the assumption of a new function in the paired 

 fins, i. e., pushing against solid objects such as 

 roots, in the stagnant water, instead of merely 

 steering. A study of the pectoral girdle and fins 

 of Sauripteris, a rhizodont crossopterygian of the 

 Upper Devonian, in comparison with those of 

 Polypterus and with the limbs of primitive am- 

 phibians, had suggested the following provisional 

 homologies : 



Crossopterygidn ■ Tetrapod 



" Inf raclavicle " ' = Clavicle 



"Clavicle" (of Parker) = Scapula 

 " Supraclavicle " = Cleithrum 



"Coracoid" (hypocoraeoid) = Coracoid (or pre- 



coracoid ? ) 

 "Scapula" (hypercoracoid) = Humerus 

 Proximal basals = Radius and ulna 



Distal basals = Carpals 



Radials . = Metacarpals and 



phalanges 

 Dermal rays (derived from 



=: Nails, scales 



The reduction and loss of the post-temporal may 

 have accompanied the freeing of the shoulder 

 girdle from the skull. These views differ radically 

 from those of Owen, Parker and Gegenbaur. The 

 paired fins of Sauripteris were the only ones 

 known that seemed to foreshadow even in a re- 

 mote degree the paired limbs of the Tetrapoda. 

 In the pelvic fin of Eusthenopteron, another cross- 

 opterygian of the Upper Devonian, differential 

 evolution of the basals and radials had brought 

 about certain remote resemblances to the tetrapod 

 limb. The ilium of tetrapods appeared to be a 

 neomorph. 



L. HUSSAKOP, 



Secretary 



THE AMERICAN CHEMICAL SOCIETY 

 NEW" YOKE SECTION 



The sixth regular meeting of the session of 

 1910-11 was held at the Chemists' Club on March 

 10, Professor Chas. Baskerville in the chair. 



The election of officers of the section for the 

 session of 1911-12 resulted as follows: 



Chairman — A. G. Langmuir. 



Vice-chairman — A. B. Lamb. 



Secretary and Treasurer — C. M. Joyce. 



Executive Committee — Chas. Baskerville, David 

 Wesson, W. J. Evans and Rudolph Seldner. 



The following papers were presented: 



' ' The Sulphides of Iron, " E. T. Allen. 



' ' The Detection of Salicylic Acid, " H. C. Sher- 

 man and A. Gross. 



"A Study of the Factors involved in the Quali- 

 tative Determination of Barium, ' ' E. Prankel and 

 L. J. Curtman. 



' ' The Detection of the Platinum Metals by the 

 Glow Reaction," P. Rothberg and L. J. Curtman. 



' ' Some New Rare Earth Compounds, ' ' Charles 

 James. 



' ' Experimental Furnaces for Glass Melts, ' ' P. 

 C. McUhiney. 



' ' Examination of Commercial Oxygen, ' ' Reston 

 Stevenson and Chas. Baskerville. 



Before the reading of the last paper, the chair- 

 man asked Dr. A. H. Sabin, the first chairman of 

 the section, to preside. Dr. Sabin, in taking the 

 chair, gave a short account of the early history 

 of the section. 



Dr. McMurtrie had hoped to be present to make 

 some valedictory remarks on the occasion of the 

 last meeting in the original quarters of the Chem- 

 ists' Club but was obliged to send a written com- 



