Hagen.] 178 [December 27, 



Practically, when a naturalist can unite by means of intermedi- 

 ate links any two forms, he treats the one as a variety of the 

 other; ranking the most common, but sometimes the one first 

 described, as the species and the other as the variety. But cases 

 of great difficulty, which I will not here enumerate, sometimes 

 arise in deciding whether or not to rank one form as a variety of 

 another, even when they are closely connected by intermediate 

 links ; nor will the commonly assumed hybrid nature of the inter- 

 mediate forms always remove the difficulty. In very many cases, 

 however, one form is ranked as a variety of another, not because 

 the intermediate links have actually been found, but because 

 analogy leads the observer to suppose either that they do now 

 somewhere exist, or may formerly have existed; and here a wide 

 door for the entry of doubt and conjecture is opened. 



General Meeting, January 3, 1883. 



Vice President, Mr. F. W. Putnam, in the chair. Nineteen 

 persons present. 



Prof. Henri Milne-Edwards and Prof. Rudolph Virchow were 

 elected Honorary Members. Dr. Wm. B. Carpenter, Prof. 

 Joseph Prestwich, Prof. Alphonse Milne-Edwards and the 

 Marquis de Saporta, were elected Corresponding Members. Capt. 

 A. R. McNair, U. S. N"., and Mr. Bernard P. Verne were elected 

 to Associate Membership. 



Mr. C. O. Whitman described a rare form of the blastoderm of 

 the chick, in which the primitive groove extended to the very 

 margin of the blastoderm, terminating here in the marginal notch 

 first observed by Pander. 



The blastoderm was eighteen .hours old, and nearly one centimeter in 

 diameter. The extension of the primitive groove to the marginal notch 

 was regarded as a re-appearance of a developmental feature, which is con- 

 stant in some of the lower vertebrates and their nearest invertebrate allies, 

 but which has ceased to be a normal occurrence in the development of the 

 chick. 



