better knmvn as the Coccoh'th. 187 



Loc. Atlantic-Ocean bottom; Laminarian zone, south coast of 

 Devon. Probably universal. 



Obs. There appears to be no difference between this species 

 and the oval one of the Atlantic bed. It is also accompanied 

 by the smaller and more simple forms designated by Professor 

 liuxley "discoliths" {I c. Hg, 2,a,b,c), which, for reasons 

 that will appear hereafter, I am inclined to consider immature 

 or young specimens of M. uniceUidaris. 



But there is another kind present in the mud of the Atlantic 

 bed, which, although less plentiful, is, from its circular form 

 (Huxley, I.e. p. 208, fig. 4, «, b,c), distinctly different from the 

 oval M. unicellular is ; and for this form I propose the following 

 name and description. 



Melohesia discus, milii. 



Cell calcareous, discal, circular, transparent, convexo-concave; 

 consisting of two concavo-convex disks, one a little larger 

 than the other, the larger receiving the smaller one in its 

 concavity ; enclosing a granular proto])lasmic disk with 

 central transparent area, which is circular and contains a 

 granule. Mode of propagation unknown. Size about 

 l-2300th of an inch in diameter. 



Hob. Marine, accumulating in beds. 



Loc. Atlantic Ocean. 



Obs. From the distinctly circular form of this species, from 

 its being entirely absent in the Laminarian zone here, so far 

 as my observation extends, and from its forming, as will be 

 hereafter seen, exclusively the species which is present in 

 some of the bodies described by Prof. Huxley under the term 

 of " coccospheres," previously proposed for them by Dr. Wal- 

 licli (Annals, 1861), I think there can be no doubt that it 

 should have a special designation. 



Coccospheres. 



Seeing that the lower marine animals fed so plentifully on 

 M. unicellular es, and that these as well as the coccosphere 

 formed of them appear in the tag-like appendages of Myxo- 

 brachia rhopalum, Hackel (Quart. Journ. Microscop. Sci. 

 Jan. 1871, pi. 5. fig. 4), while fully aware of the rotatory mo- 

 tion and spherical form of the food-pellets in the alimentary- 

 cavities of the Infusoria respectively, and the globular one in 

 which the excrementitious parts are often voided, I at first 

 thought that the coccospheres might originate in this way ; 

 but a subsequent examination of them as they occur in the 

 deep-sea mud (for I have never met with any here) has in- 

 duced me to change my opinion. 



