No. 2.] AMPHIUMA MEANS. 383 



appear. The parapophysial spine remains constant for the 

 important muscular attachments. The many processes and 

 depressions characterizing the bones of AmpJiiiima present but 

 slight genealogical significance until we have made a careful 

 study of the muscular system. 



MusctUar System.. 



During the past six months I have searched carefully for a 

 description, or even a few words of introduction, to the muscu- 

 lar system of this strange animal, but have been able to find 

 only a very terse discussion of the subject. This is given by 

 Dr. Bronn (10), and consists of a few words concerning the 

 muscles of the head. A brief account of the dorsal muscles 

 was published by the writer (6) in April, 1 894. A satisfactory 

 dissection of the muscles requires considerable and careful 

 preparation of the tissues, owing to the fact that the muscular 

 arrangement is so complex and many of the muscles are so 

 minute and massed together. After much experimenting I 

 found the following fluid a most admirable agent for the macer- 

 ation and differentiation of the muscular elements : one part 

 of one-fourth per cent chromic acid, two parts of ten per cent 

 nitric acid, two parts of seventy per cent alcohol, and three 

 parts of water. The specimen may be left in this fluid a 

 week, at the end of which time it must be thoroughly washed 

 in running water for several hours. Then the muscle-fibres 

 will be found stained a bright red, while the fascial envelopes 

 will remain uncolored and the tendinous origins and insertions 

 will be swollen so as to be readily seen. 



Great difficulty is experienced in neatly separating the skin 

 from the underlying muscles, since the two are indissolubly 

 connected by an exceedingly tough fascia. This fascia con- 

 sists of a dense sheath of tissue arising from the neural spines 

 in two plates, which, scarcely separated at their origin, diverge 

 gradually as they rise to the dorsal surface, thereby bounding 

 laterally an area whose cross-section is triangular. This area 

 is filled with a loose connective tissue and fatty substance. 

 Each plate of fascia is reflected over the external surface of 



