On JOURNAL OF COMPARATIVE NEUROLOGY. 
previous contributions by this author. ‘The more important of the con- 
clusions reached are included, along with others, in the extract from 
the catalogue of the museum of the Royal College of Surgeons given 
above, and need not be summarized here, save to add one point: 
‘‘'The features of the Prosimian brain become really intelligible only 
on the supposition that the Lemurs have advanced a considerable dis- 
tance in the main stream of the evolution of the Primates and have 
then retrograded; among other manifestations of this retrogressive pro- 
cess many interesting phases of the disintegration of the cerebral sulci 
are exhibited, so that it becomes possible to recognize the constituent 
elements of many compound sulci in the Primates, and so the more 
readily to compare them with the furrows found in other mammals.” ° 
C. “5a 
Development of Lepidosiren.' 
This contribution treats of the general epidermis, buccal cavity, 
hypophysis, central nervous system and sense organs, and is illustrated 
by four excellent plates. Notable among the figures are drawings of 
the brain from different aspects at successive stages, showing also the 
roots of the cranial nerves. Typical fourth and sixth nerves were 
found and figured for the first time. 
The brain of the adult Lepidosiren closely resembles that of Pro- 
topterus. The thalamencephalon and mesencephalon do not become 
marked off from one another until relatively late and the cerebral 
hemispheres arise as two separate lateral bulgings of the wall of the 
thalamencephalon. ‘The most distinctive feature of the contribution is. 
concerned with the histogenesis of the motor nerves, of which we are 
promised a more full description later. ‘The motor nerve trunks are 
already laid down at a period when myotom and neural tube are still 
in close apposition. As development proceeds and the myotom re- 
cedes from the spinal cord the nerve trunk lengthens out, increases. in. 
thickness, and becomes ensheathed in mesenchymatous protoplasm. 
At the earliest stage observed the protoplasm of the nerve trunk is. 
continuous with that of the myotom cells, which are provided with 
tail-like processes extending into the nerve. C, Jaies 
1KERR, J. GRAHAM. The Development of Lepidosiren paradoxa. Part IIT- 
Development of the Skin and its Derivatives «, Quart. Journ. Micr. Sct., N. S., 
vol. XLVI, 1902. 
