Gray.] 114 [October 7, 



it was published, its importance to the student has not at all 

 diminished. 



Next to this in extent and value may be ranked Prof. 

 Wyman's paper on the development of the common skate of 

 our waters (Eaia Batis), communicated to the American 

 Academy in 1864, and published among its Memoirs. It 

 gives an account of the peculiar egg-case of the Selachians, 

 and of the several stages of the development of the embryo 

 skate, expressed in the concise and clear language — as little 

 technical as possible, — for which he was distinguished, and 

 leading up to not a few problems in comparative anatomy, 

 morphology, or systematic zoology, — problems which Prof. 

 Wyman never evaded when they came directly in his way, 

 and seldom handled without making some real contribution 

 to their elucidation. For instance, in describing the external 

 branchial fringes of the young skate, he notes the agreement 

 In this character with the Batrachians ; and in studying the 

 -seven branchial fissures of the embryo, he is brought into 

 contact with the view of Huxley, that the formation of the 

 external ear is by involution of the integument. After con- 

 firming the contrary observations of Reichert, on the embryo 

 .pig, he concludes that " the first of the seven branchial fis- 

 sures of the embryo skate is converted into the spinacle, 

 -which is the homologue of the Eustachian tube and the outer 

 ear-canal." After a full discussion of the homology of the 



roots and a ganglion ; that there are no nerves to indicate a fourth vertebra, unless 

 the special sense nerves are considered; if these are admitted as indications, then 

 we must presuppose either two pairs of nerves to each vertebra, or the existence 

 of six vertebral, which is a larger number than can be accounted for on an osteo- 

 logical basis. The functions and mode of development of the special sense nerves 

 we have taken as affording sufficient grounds for considering them as of a peculiar 

 order, and not to be classified with common spinal nerves." 



