SOMi: COLLEMBOLA OF LAGl NA HI-ACH 



(IKKTHI'DK incoN 



This paper is tin- Hrst of a scries to lie written upon tlu- ( 'iillemlKila. 

 it is tile result ol' work upon s|)eeiniens eolleeted at IjUKunu Heaeli. Califor- 

 iiiii. (luring tile suiiiiiier months of July ami August, 1!n2. 



The eoast at iiaguna is very meky and is a most fnvorahle piaet- for 

 'licri' colleetin}; at hiw tide, for at that time the rocks covcri-il witli s)»awee<l 

 arc exposed for considcrahle distance oceanward. Along some parts of the 

 licacli the r(.cks can he overturned and it was on the underside of these that 

 the ('i:|lendM la were found. When the stones were overturned the ( 'olleniholn 

 did not appear at once, luit after most of the water had drained off. They 

 were caught l>y a camel's hair lirush that had hecn dipped in alcohol. These 

 insects \vcr<' net found in all rocks hut were most numerous on large ones, 

 the upper sides of which were thickly covered with algtc, and the under sides 

 «itli !\ grciit nmiilicr of worm cases, sniidl Imlcs and cavitii's. They were 



\::..„^ ^J 





Figure 267. Isotoma bidenticula Giitli. 

 I'Tiiiii the side. 



never found on the upper side or on the under side of small, smcMith stone.s. 

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

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

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

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

 as far out in tlie water as it was possilile to turn over the stones, although 

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

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

 iiiciiths at a time. ('. 1!. Davenport has descrilied .some ('ollemlM)la from 

 ('(Id Spring Hcach hut entirely in relation to the .sand. None were found at 

 Lasuna en the heaeh in tlu' sand; they were confined entirely to tin- roek.s. 

 However, one of the species. Isoloinn hissilsii, that Davenport found in the 

 sand was found at Laguna. It has a dilTcrent relation at Iwtguna. jinihahly it 

 remains in air cavities under the rocks on this coast. 



