ALG.E. 



191 



water, they impart to the brash and pancake ice a 

 pale ochraceous colour. 



As representing some of the forms of the diatom 

 valve, as found in deposits, we give figures of two of 

 the larger forms from the Monmouth deposit, found 

 in Maine, United States. They belong to the two 

 genera of diatoms respectively known as Stauroneis 

 (Fig. 32) and Pinnularia (Fig. 33), of which many 

 species are known, both recent and fossilized. 



Still more beautiful are some of the discoid forms 



FiG T,i,.~ A ulaco discus Kittoni, from Peruvian guano. 



which are found in guano and elsewhere, and the 

 quadrangular or star-like forms from similar sources. 

 Of these the species of Aitlacodiscus (Fig. 34) was 

 obtained from Peruvian guano, and the AinpJiitetras 

 (Fig. 35) from^ guano of Algoa Bay. These can give 

 little idea of the variety of form and markings of the 

 very numerous species already known. These valves 



