THE ANTERIOR CRANIAL NERVES OF PIPA 

 AMERICANA. 



BY G. A. ARNOLD. 



THIS study was undertaken to extend the method of se- 

 rial sections so successfully employed by Von Plessin and 

 Rabinowicz ('91) on Salamandra maculata, to one of the 

 Anura. The embryos of Pipa, which form the basis of 

 the study, had a body length of 9 mm. and were cut trans- 

 versely into sections 22 micra thick, stained with alum 

 cochineal and Bleu de Lyon (the latter after Rose's method 

 ('91), and the reconstructions were made by plotting the 

 projections of the sections on cross-section paper. It is 

 only by such methods that detailed and conclusive knowl- 

 edge can be obtained of the distribution of the nerves in 

 the smaller forms. Since this method has been used in so 

 few instances, comparison with other Batrachia is impossi- 

 ble and so the text is solely descriptive. It is, in fact, but 

 an extended explanation of the plate to which reference 

 must be made for all details. In my account of the several 

 nerves, I have omitted detail with regard to such features 

 as are common to all Batrachia and have dwelt more es- 

 pecially from points previously unknown or apparently 

 peculiar to this form. So far as I am aware the nervous 

 system of Pipa has been studied previously only by J. G. 

 Fischer whose paper, unfortunately, is not to be found ill 

 the libraries I have consulted. 



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