G. NATURAL HISTORY AND ZOOLOGY. 317 



oping very rapidly in spring and the beginning of summer, 

 covering the upper layers of mud in large masses, and con- 

 sisting of an aggregation of little grayish bodies of from one 

 to two millimeters in diameter, with others still more minute 

 intermixed. Under the microscope, the JPelotnyxa^vhen con- 

 tracted, presents a spherical and ovoid or lenticular shape, 

 composed of protoplasm, in which two different layers can be 

 distinguished, one external and the other internal. The out- 

 er, or pure protoplasm, is hyaline, and more viscous than the 

 interior. It is full of vesicles, projecting above the surface 

 of the mass, and sometimes lobed or digitated, into which the 

 internal surface penetrates as into a sac. These prolonga- 

 tions break or run together in the amoeboid movements which 

 the Pelomyxa carries on. 



Further details in reference to this animal are too technical 

 to be here reproduced. The conclusion to which Dr. Greef 

 comes, in regard to its affinities, is that it is a multicellular 

 organism, constituting the representative of a group of amoe- 

 boid objects with multiple nuclei, belonging to the class of 

 Ilhizopods, and especially allied to several kinds of Myxomy- 

 cetes. 1 F^ December 15, 1S73, 361. 



NEW FOSSIL SPIDER. 



Among other recent interesting announcements is that by 

 Mr. O. Harger of the discovery in the coal measures of Illi- 

 nois of a fossil spider, to which the name Arthrolycosa anti- 

 qua has been applied. 



SUCCESS OF THE NAPLES ZOOLOGICAL STATION. 



Mr. E. Ray Lankester writes from Naples to announce the 

 complete success of the zoological station and aquarium es- 

 tablished by Dr. Dohrn, the resources of which are no % w util- 

 ized by a large number of specialists and students in various 

 branches of natural history. The well-known variety of ani- 

 mal life in the Mediterranean permits the marine aquaria to 

 be densely stocked with the most curious objects; and their 

 examination is not simply a passing amusement, but a means 

 of making important discoveries in regard to their natural 

 history. 



The expense of erecting the establishment has been borne 

 by Dr. Dohrn ; the means of keeping it up, however, are to 



