2550 KANSAS CITY REVIEW OF SCIENCE, 
In sections of the Atlantic, so abundant at the surface in tunicate that the sea 
-seemed actually like a moving mass of life, genera and species were as numerous 
and varied at fifty fathoms as they were upon the immediate surface. The next 
fifty fathoms contained the same types, but the genera were less numerous. They 
-counted seventeen genera of pelagic organism upon the immediate surface in one 
-of those investigations, but only five of them were brought up when the trap was 
det down to a depth of too fathoms. Prof. Agassiz concluded with a high com- 
pliment to the ingenuity of Commander Sigsbee, whose invention had surmounted 
‘so many difficulties connected with the study of submarine biology. He believed 
that the bodies of pelagic organisms brought up from great depth were the car- 
-casses of animals that had perished of age or accident upon the surface, and had 
slowly settled to the bottom to furnish food for its living hosts. It required from 
‘three to four days for a dead tunicate to sink to a depth of 1,000 fathoms. 
With the paper of Prof. Marsh on the ‘‘ Dimensions of the Brain and Spinal 
‘Cord in Some Extinct Reptiles,” the work of the season was closed. Prof. Marsh 
reminded the members of the academy by way of introduction that some five 
years ago he had contributed a paper on the dimensions of the brain in extinct 
‘mammals, and had then established the proposition that the older the type the 
‘smaller was the dimensions of the brain. Among the mammals of the Tertiary 
period there had been a gradual increase in the capacity of the brain-box and in 
ithe volume of the contained nervous tissue. Moreover, this increase in volume 
had mainly concerned the cerebral or intellectual portion of the encephalon, so 
that it might be urged that there had been a gradual advance in intelligence asso- 
‘ciated with this advance in brain development. Since laying before the academy 
his memoir on the mammalian brain he made many more observations, and in 
April last last, as his hearers would remember, he had the honor of laying before 
the academy evidence of the fact that the same law of progressive increase in 
‘cerebral volume was followed by reptiles and fishes by comparing the brains of 
extinct with those of surviving genera and species. In general the brains of the 
earlier types were not more thon one-third as large as those of the corresponding 
‘types of the Tertiary period, and this was true of all the different groups he had 
examined, embracing the crocodiles, dinosaurs, as well as the higher forms. He 
should call attention at present to the small brain of a gigantic reptilian of the 
jurassic formation which he had recently examined. This immense animal, 
though thirty feet in length, possessed a brain scarcely as large as that of an or- 
dinary dog, as judged from the capacity of the brain cavity. But the most re- 
markable feature of its nervous system was an immense enlargement of the spinal 
cord in the sacral region, where the bone was so excavated as to form an immense 
vaulted receptacle several larger than the brain cavity. ‘The sacrum consisted of 
four vertebree, which were well ossified and of great solidity, and within this was 
contained, during the life of the animal, a posterior brain—if he might use the 
term—which was eight times as Jarge as the encephalon. ‘The point was of very 
‘curious interest, not only as a fact of fossil anatomy, but in respect to the physio- 
