JEFFRIES WYMAN. 391 
skull, and supports the opinion that they also are only three 
in a characteristic manner.! 
Of this whole memoir it is thought that, notwithstanding 
the great advance which has been made in comparative ana- 
tomy during the twenty-five years which have elapsed since 
it was published, its importance to the student has not at all 
diminished. 
Next to this in extent and value may be ranked Professor 
Wyman’s paper on the development of the common skate of 
our waters (Raia Satis), 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 zodlogy,— problems which Pro- 
fessor Wyman never evaded when they came directly in his 
way, and seldom handled without making some real contri- 
bution to their elucidation. For instance, in describing the 
external branchial fringes of the young skate, he notes the 
agreement of this character in the Batrachians; and in 
studying the seven branchial fissures of the embryo, he is 
1 «“ The conclusions which have been drawn from the statements made 
above are as follows: that in frogs the vagus comprises the glosso-pharyn- 
geal and accessory nerves ; that the trigeminus comprises the facial, the 
abducens and in the salamanders the patheticus and portions of the motor 
communis ; that other evidence sustains the hypothesis, that the whole of 
the motor communis is a dependence of the trigeminus ; if to these we 
add the hypoglossus (which in frogs is exceptionally a spinal nerve), we 
shall have three pairs of cranial nerves, each having all the characters of 
a common spinal nerve, namely, motor and sensitive 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 exist- 
ence of six vertebre, which is a larger number than can be accounted for 
on an osteological 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 com- 
mon spinal nerves.” 
