Garman.] 198 [May 2, 



cepted," or " the common idea of special creations." The theory of 

 origin which has built itself in my studies, and which in the present 

 state of my knowledge seems most reasonable and susceptible of 

 proof, asserts (I) that life began at different places and times, (II) that 

 from commencements at different places and at various times series have 

 developed which are now represented by groups of types of more or less 

 resemblance, (III) that the earlier types were surrounded by less favor- 

 able and more simple conditions, and, in consequence, remained of lower 

 grade, and (IV) that the conditions under which the last types have ad- 

 vanced necessitated rapidity of development, complexity of organiza- 

 tion, and, consequently, the highest rank. 



As a theory it is a combination of evolution and what might an- 

 swer for special creations, which requires less of proof for its estab- 

 lishment than the one, and less of abstract credulity for its belief 

 than the other. Whatever started and developed a single series was 

 competent to do all that is required by this theory. All the proof 

 that has yet been advanced in support of evolution in any form sup- 

 ports it, and the " missing links " are in its favor. 



Such a position makes it necessary, in the study of animal resem- 

 blances, that the student avoid mistaking for genetic affinities 

 similarities which owe their origin and accumulation to physical 

 conditions, and their perpetuation to heredity. It leaves one at lib- 

 erty to believe, until it is proven otherwise, that such animals as 

 Chiinasra and the Shark had no common ancestor; or, on the other 

 hand, that numerous species of what we now designate as genera 

 had a common parentage. 



As this communication is brought forward to place on record and 

 secure certain things, rather than to publish entire the conclusions 

 drawn or the generalizations reached, I shall confine myself, as far as 

 may be, to statement, reserving special remarks upon affinities, 

 eauses, etc., until able to publish the drawings. 



Throughout the class Selachia the pelvis is free from the balance 

 of the skeleton. Its only connection with the vertebral column is 

 ligamentary, by means of the muscles and their fascia?. The upper 

 (iliac) extremities end between or upon the layers of muscle near 

 the middle of the side, in such as have round bodies. Attached to it 

 are the ventral fins, bearing the claspers in the male, and the muscles 

 required for their movement. Two very distinct types of this organ 

 obtain in the class: one peculiar to the Chirnasrae, the other common 





