Miscellaneous. 167 



Small Size of the Brain in Tertiary Mammals. 

 By Prof. 0. C. Marsh. 



At the last meeting of the Connecticut Academy of Arts and 

 Sciences, June 17th, Prof. Marsh, of Yale College, made a communi- 

 cation on the size of the Drain in Tertiary mammals. His researches 

 on this subject have been mainly confined to the larger extinct 

 mammals which he had obtained in the Rocky-Mountain region ; 

 and the results are of peculiar interest. The Eocene mammals all 

 appear to have had small brains ; and in some of them the brain- 

 cavity was hardly more capacious than in the higher reptiles. The 

 largest Eocene mammals are the Dinocerata, which were but little 

 inferior to the elephant in bulk. In Dinoeeras, Marsh, the type 

 genus, the brain-cavity is not more than one eighth the average 

 size of that in existing rhinoceroses ; in the other genera of this 

 order (Tinoeeras, Marsh, and Uinta therium, Leidy) the smallness of 

 the brain Avas quite as remarkable. The gigantic mammals of the 

 American Miocene are the Brontotheridae, which equalled the Dino- 

 cerata in size. In Brontotherium, Marsh, the only genus of the 

 family in which the skull is known, the brain-cavity is very much 

 larger than in the Eocene Dinoeeras, being about the size of the 

 brain in the Indian rhinoceros. In the Pliocene strata of the West 

 a species of Mastodon is the largest mammal, and although but 

 little superior in absolute size to Brontotherium, it had a very much 

 larger brain, but not equal to that of existing Proboscidians. The 

 tapiroid Ungulates of the Eocene had small brain-cavities, much 

 smaller than their allies, the Miocene Rhinocerotidae. The Pliocene 

 representatives of the latter group had well- developed brains, but 

 proportionally smaller than living species. A similar progression in 

 brain-capacity seems to be well marked in the equine mammals, espe- 

 cially from the Eocene Orohippus, through Miohippus and Anchithe- 

 rium of the Miocene, Pliohippus and Hipparion of the Pliocene, to the 

 recent Equus. In other groups of mammals likewise, so far as ob- 

 served, the size of the brain shows a corresponding increase in the 

 successive subdivisions of the Tertiary. These facts have a very 

 important bearing on the evolution of mammals, and open an in- 

 teresting field for further investigation. 



On Euphysetes Pottsii. By Dr. Julius Haast, F.R.S. 



This small Catodont whale was stranded amongst the rocks in 

 Governor Bay, near Ohinitahi, and Avas sent by Mr. T. H. Potts to 

 the Canterbury Museum, NeAV Zealand. It was an adult female, 

 7 feet 2 inches long, and very like Euphysetes Grayi ; but that 

 species has 7 cervical, 14 dorsal, 9 lumbar, and 21 caudal vertebras 

 (of which 13 have chevron bones attached), making 51 altogether. 

 Euphysetes Pottsii has only 50 vertebras ; and they are differently 

 arranged. The 7 cervical vertebrae are soldered together ; there are 

 only 12 dorsal (instead of 14), 11 lumbar (instead of 9), and 20 

 caudal with 8 chevron bones attached (instead of 21 ). 



