1895 THE MICROSCOPE. 75 



by the Chinese in making a soup. Many years ago 

 microscopists got tiie Arachnoidiscus from it. The 

 Algse are brought by the cura siwa or Japanese current 

 to the west coast of North America and there the Bacil- 

 lariacesB are abundant. Aranchnoidiscus ehrenbergii 

 is common in the mouth of the Columbia river in Wash- 

 ington and I have it from there sent to me by Miss A. 

 L. Pollock. It is also common in the harbor of San 

 Francisco where Igatherd it myself in 1877, and on the 

 coast until we come to San Diego where it is common. 



And this brings me to the statement that Arachnoidis- 

 cus ehrenBergii J. W. B. is the only form or species of 

 the genus, the others seeming different but not being 

 realy so. 



There are eleven forms or species of Arachnoidiscus, 

 some from recent gatherings and some from fossil, 

 some from California, New Zealand, Barbadoes and Spain 

 but all the same. 



It was called by Ehrenberg, Hemiptycus but this 

 name was used for a genus of insects and so Arachno- 

 discus was adopted. It is named from its looking like a 

 spider's web. There are also present in the Agar-agar 

 specimens of Grammatophora marica FTK andCocconeis 

 scutellum C. Gr. E. and Cocconeis pseudomarginata A. Gr. 

 which I am disposed to think is a variety of C. scutellum. 

 At all events the Bacillariacese are scarce in the agar- 

 agar. Spicules of sponge are also found. 



Vaselin in Microscopy. — Gawalowski proposes to replace 

 cedar oil and other liquids used for oil immersion for objectives 

 by vaselin, whose refractive index is 1.40. — Rundschau. 



Fine Mounts of Caterpillars. — Mr. C. P. Bates, 853 Main 

 street, Petaluma, Sonoma County, California, prepares fine 

 mounts of Caterpillars. We advise those who are intereste d in 

 the subject to correspond with him. 



