Ryder.] 5d4 [Oct. 4, 



Dr. Morris moved to amend by striking out all after the 

 word Periodicals. 



Mr. Horner moved to amend by inserting after Periodicals 

 the words " taken bj them." 



Prof. Ileilprin moved to amend bj inserting after Periodi- 

 cals the words " including Transactions and Journals." 



The amendments were accepted by the original mover, and 

 the resolution, as finally amended, was unanimously adopted 

 as follows : 



Resolved, That the Secretaries be authorized to communicate with the 

 officers of the other scientific societies and libraries in Pliiladelphia, for 

 the purpose of preparing a Union List of Scientific Periodicals, including 

 Transactions and Journals taken by them. 



And the Society was adjourned by the presiding member. 



The Phylogcny of the Sweat- Glands. 



By Prof. John A. Ryder. 



{Read before the American Philosophical Society, October 4, 18S9.) 



The suggestion of the descent of the Mammalia through a reptilian an- 

 cestry has been favorably received by many naturalists. In this connec- 

 tion, those singular Permian types described b}' Prof. Cope under the 

 name of Theromora may be recalled. The Theromora present certain strik- 

 ing resemblances to the monotreraes, but what their integuments may have 

 been like in microscopic structure we shall probably never know. And it 

 is just upon this question of integumentary structure that much of high 

 taxonomic importance rests. Upon examining the integument of A^erte- 

 brates the general plan of structure is found to be very similar in all of the 

 orders. The main differences arise (1) through variations in the thickness 

 of the epiblastic epidermis and the mesoblastic dermis or corium ; (2) the 

 arrangement of the connective-tissue fibres of the latter, and (3) the ab- 

 sence or degree of development of glands in connection with the epi- 

 dermis. 



The tendency of the fibres of the corium to interlace in three directions 

 in fishes is marked, and may be best seen in selachians and chondrosteaus, 

 while it is equally striking amongst Marsipobranchii. The fibres seem to be 

 disposed in annular layers, between which longitudinal layers are disposed, 

 while the whole is firmly bound to the subcutaneous connective tissues by 

 fibres which traverse the meshes of both the preceding layers, this third 



