1871.] 351 [Morse. 



cumstances, he crossed our thresholds again, and took his 

 wonted place in our households. Thenceforth, to the year of 

 his death, he passed his summers in New England. He was 

 a cherished guest under many a northern roof, but his perma- 

 nent northern home was at North Wrentham, now more 

 commonly called Norfolk. There he died among his broth- 

 ers and sisters and their families, in the village where his 

 infancy and boyhood were passed, and where he was ever 

 regarded with the tenderest affection and respect. 



Prof. Edward S. Morse read the following paper : — 

 i 



Notes on the Early Stages of an Ascidian (Cynthia 

 pyriformis, Eathke). By Edward S. Morse, Ph.D. 



PLATE I. 



In the year 1866, Kowalevsky published a remarkable series of 

 observations on the embryology and early stages of several Ascidians, 1 

 in which a structure similar, if not identical, with the type characters 

 of the vertebrata was demonstrated. 



Professor KupfFer at first doubting, then not only confirms the 

 validity of Kowalevsky's observations, but adds additional facts show- 

 ing that the nerve mass actually penetrates the tail of the embryo to 

 a considerable length. 2 



The important facts revealed in these investigations have led the 

 eminent naturalists above mentioned, as well as Hseckel, Schultze, and 

 others, to believe that the connecting link between the Vertebrates 

 and Invertebrates had at last been established. 



Darwin, with prompt recognition has incorporated the facts in his 

 last work on the "Descent of Man." 



Since Kowalevsky's memoir above referred to was published, he 

 has traced out the embryology of Amphioxus 3 in which the closest 

 resemblance is seen between this low vertebrate and similar stages of 

 the Ascidian. 



In these unsuspected relations between the Vertebrates and Ascid- 

 ians through Amphioxus, it is interesting to remark that long ago 



1 Kowalevsky, Mem. Acad. Imp. St. Petersburg, Series vn, Tom. x, 3, 1866. 

 2 Kupffer. Schultze's Archiv. fur Mikrosk. Anatomie, Bd. 6, 1870. 

 8 Mem. Acad. Imp. des Sci. St. Petersbourg, vn Series, Tome xi, No 4. 



