166 PROCEEDINGS OF THE ACADEMY OF 



and the genera Symhorodon and Miobasileus of Prof. Cope be- 

 long. 



Last summer, in passing through New Haven, I had an oppor- 

 tunity of seeing the fossils referred by Prof. Marsh to Brontothe- 

 rium. Among them I saw an incisor tooth, which is like one in 

 the museum of the Academy-. Tlie latter specimen accompanied 

 some remains of Tit another ium from White River, Dakota. The 

 crown forms an irregular hemisphere, and measures from 5 to 5^ 

 lines in diameter. 



The examination of the skull, described by Prof. Marsh, under 

 the name of Brontotherium, and an inspection of the skulls, ex- 

 hibited to the Academy last June b}^ Prof. Cope, and referred by 

 him to Symborodon, confirmed m}' suspicion that these two named 

 genera are synonymous with Titanotheriian. I also suspect from 

 the cursory examination of the specimens of Profs. Marsh and 

 Cope, that the number of species will probably be reduced to one 

 or two. 



Notices of Rhizopods. Prof. Leidy exhibited drawings of the 

 beautiful Actinophryan, Clathrxdina elegans^ described by Cien- 

 kowski and other European naturalists. It was found abundanth'' 

 on Utricularia, at Absecom, New Jerse}-. The more mature speci- 

 mens have a brownish or yellowish color. The spherical, fenes- 

 trated, siliceous shell measures from ^^th to ^^-th mm. in diameter. 

 The intei'ior Actinophrys-like body is about ^^^'^ vava. in diameter, 

 and gives off a multitude of delicate rays which extend thi-ough 

 the fenestra of the shell. The stem of attachment of the shell 

 measures ^th of a mm. or more in length. 



The maturer specimens frequentl}' have others attached to their 

 shell, usually one, but as many as six wei*e observed radiating on 

 their slender stems from the parent shell. These secondary shells 

 are slightly smaller than the others, are colorless, and ofteu so 

 delicate and transparent that the fenestrate character, if it exists, 

 is invisible. 



In a number of detached specimens of Clathrulina^ the shell 

 was occupied by a central, rayless, granular mass, from ^^^th to 

 ^'pth mm. in diameter. 



Prof. Leidy also exhibited drawings of Actinosphserium Eich- 

 Jiornii, which, though not so common as Adinophrys sol, is fre- 

 quentlj' found in the ponds and ditches in the vicinity of Phila- 

 delphia. It varies considerably in size, ranging from jVth mm. 

 to I ram. in diameter. Some exhibit a multitude of rays, others 

 a few, and some observed, of large size, alive and active, were 

 utterly rayless. 



Drawings were also exhibited of Acanthocystis viridis. This 

 remarkable rhizopod occurs frequently in all the ponds and ditches 

 in the vicinity of the city. It is either very pol^-morphous, or else 

 perhaps several species may be included under the one name. 



