42 PROCEEDINGS OF THE ACADEMY OF 



On a closer examination it turned ont that they were acute 

 rhombohedrons with four planes largely and the other two planes 

 only very minutely developed, thus giving to the crystal the ap- 

 pearance of a tetrahedron or sphenoid, two of whose angles were 

 truncated l^ small planes. 



It suggested itself as a means of obtaining crystals from a 

 saturated carbonic acid solution of those substances not readily 

 soluble in pure water, to allow the gas to escape uniformly but 

 slowly, and thus allow each crystal time to complete its comple- 

 ment of planes. 



April 30. 



The President, Dr. Ruschenberger, in the chair. 



Twenty-nine members present. 



The death of Wm. W. Gerhard, M.D., was announced. 



The following were elected members: Geo. Stiles, M.D., Pass- 

 more Williamson, Bloomfield H. Moore, Mrs. Bloomfield H. Moore, 

 Alfred D. Jessup, Wm. F. Miskey, Wm. G. Freedly, F. B. Gowen, 

 E. Burd Grubb, Thos. R. Dunglison, M.D., and John Thompson. 



Permission being granted, Dr. H. Allen called attention to a 

 novel method of studying the appendicular skeleton of vertebrates. 

 He had found that a radiated arrangement of bones could be de- 

 tected in the shoulder girdle. The recognition of such a plan sug- 

 gested the propriety of characterizing raj^s as divergent from a 

 hypothetized centre with respect to their positions to the longi- 

 tudinal axis of the body. The scapula thus becomes the neurad; 

 the pre-coracoid and coracoid bones the heamad; while the ray of 

 the arm is the manad. The neurad ray is single and may seg- 

 ment twice, as in some batrachians, or but once, as in others of 

 the same class. The heamad rays never segment. They may be 

 single or double. The manad rays are multiple in fishes, and may 

 not diverge from a single point. In Gobius some of these rays 

 appear as actinapophyses to the neurad rays. 



The manad rays are single in other vertebrates. They do not 

 segment in fishes, but may twice segment (" glenoid "-brachium) 

 with other forms. It is necessary to remember that the centre of 

 this radiate arrangement is not at all times at the shoulder-joint, 

 but may be at a point at which the u glenoid" (Parker) scapular, 

 pre-coracoid, and coracoid bones converge. This is instanced in 

 man and the salamander. 



The study of the pelvic girdle yields similar results to those 

 above stated. The centre here is at the acetabulum. The neurad 

 ray (ilium), the two heamads (pubis and ischium), as well as the 



[June 25, 



