THE WEST AMEEICAN SCIENTIST. 71 



monly confounded with the Physalis or Portuguese man-of-war. 

 The body or disk of the Velella has an oblong shape, flattened 

 upon its uxjper and lower sides. 



A triangular sail rises on the upper side of the Velella disk 

 and extends diagonally across its surface. It is firmly joined to 

 the upper plate of the float. Over the triangular sail as well as 

 the float, there is stretched a thin, blue-colored membrane, which 

 is continued into a variegated soft rim along its border and around 

 the rim of the float. 



The Pacific Science Monthly, for June, 1886 gives the follow- 

 ing note: 



*The small jelly-fish, Velella limbosa, to which we referred 

 some weeks since, continues to be cast upon our shore by the mill- 

 ion. The beach is lined with this beautiful little medusae for 

 miles. AVhy so many appear at this season is a mystery.' 



Large numbers were washed up also on the ocean beaches at 

 San Diego and Mr. Orcutt reports them in like abundance as far 

 south as San Quentin bay, on the Lower California coast. 



The violet snail, lanthina, is said to feed on this jelly-fish, 

 but I have not learned of their having been washed ashore in any 

 numbers. 



Can any one suggest a cause for the great abundance of this 

 little animal on our coast during the months of April and May 

 this year? S. L. T. 



MONO LAKE, 



Much interest was excited at a recent meeting of the San 

 Francisco Microscopical Society, by the exhibition of some collec- 

 tions of animal and vegetable life found in and around Mono 

 Lake, made by Dr. H. W. Harkness during his recent trip to that 

 locality. Notable among them were specimens of the rare bacter- 

 ium which has been provisionally classed as Bacterium rubescens, 

 although Dr. Harkness believes there are strong grounds for re- 

 garding it as specifically new. It is found in immense quantities 

 in Mono Lake, and aggregated masses of it are of a beautiful rose 

 color. It seems to have both a still and a motile stage. No spore 

 formation has been discovered in the preliminary examinations, 

 but culture experiments are now being carried on which will no 

 doubt disclose its complete life cycle. Numerous very active in- 

 fusoria were found associated with the bacteria, and Dr. Harkness 

 reports having found many species of diatoms, some aquatic insect 

 larvae, minute crustaceans, and also fresh-water algae, in this re- 

 markable lake, the water of which is so intensely alkaline that it 



