94 PROCEEDINGS OF THE ACADEMY OP 



know there is no basis for such a, thought, and besides in other cases 

 the union of two simply crj'stallizing minerals produces one of 

 more complex morphology. 



Thus our authorities tell us that sternbergite which crystallizes 

 orthorombic is to be written chemically Ag,,S -j- (FeS)^ -{- FeS.,, 

 or in other words, is composed of three minerals, two ol^ which 

 (Ag.,S and FeS.,) crj'stallize in the isometric system, and the third 

 has no place in nature and no name. 



I propose at a future meeting of the Academy to call the atten- 

 tion of the mineralogists to several formulas which, though new, 

 seem to fulfil all the conditions of agreement with analysis and 

 the ncTvest developments of theoretical chemistry. 



The following anatomical notes by Dr. Chapman were read : 

 Disposition of the Latissimus Dorsi, etc., in Ate.les Geoff royi 

 {Kiihl) and Macacus Bhesus {Desviarest). Frequently the atten- 

 tion of anatomists is called to the abnormal arrangement of parts, 

 such as variations in the disposition of muscles, arteries, etc., and 

 by comparison with other animals what is abnormal, variable, in a 

 higher animal is usually'' found to be normal, constant, in a lower 

 one. Supposing the theory of the evolution of life to be true, 

 that the higher animals are the modified descendants of the lower, 

 we have some explanation for the occurrence of such abnormalties, 

 these variations being reversions to ancestral types. An interest- 

 ing illustration of this view is seen in the occasional occurrence in 

 man of a muscular slip, running from the latissimus dorsi to the 

 internal condyle of the humerus. This muscle, which is of very 

 rare occurrence in the human subject, is constant in monkeys, 

 among others in the spider monkej' or Ateles, as sliow^n in Plate 

 13, Fig. 1 (6). Another variation met with so frequently in the 

 human subject that surgeons have their attention called to it with 

 reference to the ligation of the main arteries, is the presence of a 

 muscular slip, passing from the latissimus dorsi across the axil- 

 lary arterj' and nerves to the pectoralis major. This muscle, Plate 

 13, Fig. 2 (c), is constant in the Macacus, which also exhibits the 

 muscular slip (6), just referred to in Ateles. On the supposition 

 that man and the monkeys are the descendants of a common 

 stock, we may expect to find such variations recurring like other 

 family traits. 



Flexor Brevis Digitorum in Ateles Geoff royi {Rube). I take the 

 opportunity of calling attention to the arrangement of the flexor 

 brevis digitorum in a sjjider monke}^, the Ateles Geolfroyi. By 

 looking at Plate 14, we see that tendons 1 and 2 are the continua- 

 tion of the muscular bell}' rising from the calcaneum, that tendon 

 3 results from the union of two muscular slips, one from (o), the 

 other from the tendinous portion of the flexor longus digitorum, 

 while tendon 4 comes only from tendon of flexor lona-us digitorum. 

 This arrangement of the tendon of the flexor brevis digitorum is 

 somewhat difierent from that observed in other New World mon- 



