1897] MiCROSCOPICAL JOURNAL. 307 



The Brain of the Embryo Soft-Shelled Turtle. 



SUSANNA PHELPS GAGE, Ph. B., 

 ITHACA, N. Y. 



In a paper read before the Microscopical Society last 

 year, upon the "Comparative Morphology of the Brain 

 of the Soft-shelled Turtle (Amyda mutica) and the Eng- 

 lish Sparrow (Passer domesticus"^)," certain questions 

 were raised, which could only be answered by studying 

 the development in the soft-shelled turtle, as : When and 

 how do the characteristic features of the brain in this 

 group of turtles arise ? When and how do those fea- 

 tures arise which distinguish them from birds ? 



Professor Eigenraann, who was present, kindly sent 

 me six embryos of Aspidinectes, a closely allied genus of 

 the turtle, in different stages of development. Serial 

 sections were made of the heads and mesal views recon- 

 structed. A brief summary of the result obtained is 

 given below. Fuller statement, with illustration, is 

 reserved until more material is studied. 



The body of the youngest specimen was 7 mm. long ; 

 the form generalized ; the face short ; the diameter of 

 the eye, one-half the length of the head. A narrow cara- 

 pace was distinguishable in a specimen, with length of 

 body 11 mm. In the oldest specimen the carapace was 

 16x11 mm., and had the characteristic leathery appear- 

 ance and markings of the adult. The snout had also the 

 elongated form of the adult. The feet were webbed. The 

 diameter of the eye, though twice as great as in the 

 youngest specimen, was only one-third the length of the 

 head. 



1. As seen from the meson, the most striking dif- 

 ference between the early and late forms of the brain 

 is the general shape. Taking as reference points the 



* Transactions American Microscopical Society, Vol. XYII., 1895, pp. 

 185— 238, -5 plates. 



