SOME COLLEMBOLA OF LAGUNA BEACH 



OERTRTIDE BACON 



'I'liis ])ai)('r is the lirst of a series to he wi-itteri upon the Collembola. 

 It is the result of work U|)on s[)eeinH'ns eolleeled at Laguua Meach, Calil'or- 

 nia, (hiring the suiumer months of July and August, 19] 2. 



The coast at Laguna is very rocky and is a most favorable place for 

 shore eolleetiiig at low tide, for at that time the roi^ks covered with seaweed 

 are exposetl foi' eonsiderahle distanee oeeanwai'd. Along some parts of tin; 

 beai'ii the rocks can he overturned and it was on the underside of these that 

 the ('cilleml)ula were found. When the stones were overturned the Collembola 

 did not apjiear at once, hut after most of the water had drained off. They 

 were caught by a camel's hair brush that had been dipped in alcohol. The.se 

 insects were not found on all rocks hut were most numerous on large ones, 

 the upper sides of which were thickly covered with alga:', and the under sides 

 with a great number of worm cases, small holes and cavities. They were 



Figure 267. Isotoma bidenticula Giith. 

 From tlic side. 



never found on the upper side or on the under side of small, smooth stones. 

 At high tide the rocks were too far under water to overturn. At low 

 tide it was found that there were no Collembola at the high tide mark. 

 Rocks at the very edge of the water contained a few and they became gradu- 

 ally more abundant farther out. At the lowest minus tide, they were found 

 as far out in the water as it was po.ssible to turn over the stones, although 

 they did not occur in as great numbers as a little nearer shore. This means 

 that these insects must remain in these rocks under water for weeks and even 

 months at a time. C. B. Davenport has described some Collembola from 

 Ccld Spring Beach but entirely in relation to the sand. None were found at 

 Laguna on the beach in the sand; they were eontined entirely to the rocks. 

 However, one of the species, Isotoma besselsii, that Davenport found in tlie 

 sand was found at Laguna. Tt has a different relation at Laguna, probably it 

 remains in air cavities under the rocks on this coast. 



