100 TRANSACTIONS OF THE , [Jae 
the many general advantages of fixing brains by injection, for- 
malin has the especial merit of giving them the best consistency 
for macroscopic work, and, further, such brains are available 
subsequently for the Golgi and Weigert methods, as well as, 
possibly, for cytological methods. Formalin also has the ad- 
vantage that it can be used, as above, stronger than is neces- 
sary for fixation and thus allowance made for its dilution when 
permeating the tissue. When only the Golgi method is to be 
used an equal volume of a 10 % solution of potassium bichro- 
mate may be added to the formalin instead of water. Pieces 
can be subsequently removed, hardened further in formalin- 
bichromate and impregnated with silver. 
Vhe third paper was the following : 
IS PALHOSPONDYLUS A CYCLOSTOME? 
BASHFORD DEAN. 
Department of Biology, Columbia College. 
Palzospondylus has seemed to fill the long-felt need of a 
Paleozoic Lamprey,—to assure the morphologist that the Marsi- 
pobranchs are in reality an ancient chordate stem, one of whose 
generalized members may in primeval times have given rise to 
the descent-line of the jaw- and paired-fin-bearing vertebrates ;— 
to convince him that there is no direct need of regarding the 
Cyclostomes, as Dohrn and others had done, as the degenerate 
survivors of highly specialized forms, perhaps akin to the Tel- 
eosts. With the recent studies of Ayers, on the one hand, 
summarizing the strikingly primitive characters of Bdellostoma, 
and with the discovery of the Lower Devonian Palzeospondylus, 
on the other, there seemed that at the present time it could not 
reasonably be doubted that the Lampreys were the descendants 
of a chordate stem both lowly and ancient. 
The more recent studies on Palzospondylus, moreover, ap- 
peared fully to confirm the early suggestion of Traquair as to 
its Myxinoid characters. Its alliance with Marsipobranchs be- 
came, ‘‘more than probable (Smith Woodward),” “a tolerably 
close approximation to certainty (Traquair), and further dis- 
coveries, when fossils should be found preserved in a matrix 
more compact than the Caithness flagstone, were looked to to 
prove, beyond a question, that its structural details were Marsi- 
