jotjbnaij of entomology and zoology 147 



Isotoma bidenticula Guthrie 

 (Plate I, Figs. 4-5) 



Isotoma hidenticula Guthrie, ColL of Minn. geol. nat. hist. surv. 



of Minn., zool. series 4, pp. 1-110. Bacon, P. C. jr. ent. and 



zool., vol. IV, pp. 841-845. 



Description: Length — 1 mm. Color — Dark, dull brown, 

 mottled; ventral side dark, light at the junction of the body 

 segments, furcula and legs light. Antennae — Short, little longer 

 than head; I shortest, II longer than III, and IV longest. 

 Ocelli — Sixteen. In each eye spot there are two which are 

 smaller than the other six. Postantennal organ is present and 

 elliptical. Claws — Unarmed. Furcula — Short, not reaching 

 ventral tube; not slender and tapering; manubrium slightly 

 longer than dentes and mucrones together. Mucrones — Biden- 

 ticulate; first tooth horizontal, long, slender, curving but 

 slightly; second tooth vertical and curves slightly cephalad. 



Variation: My specimens differ from those described by 

 Guthrie in regard to the antennae and ocelli. He describes 

 antenna III as being longer than II and the ocelli in each eye 

 spot all the same size. 



Habitat: These were found in great numbers at Laguna 

 Beach under the largest rocks below the mean tide mark at 

 low tide. 



Isotoma aquce n. sp. 

 (Plate I, Figs. 6-9) 



Description: Leng-th — 1.55 mm. Color — To the eye the spec- 

 imens look light green but under the microscope they are a 

 mottled blue and yellow. Antennae — Short, same length as 

 head; I, very short; IV, II and III all subequal. Postantennal 

 organ — Present, large, an oval rim constricted in three places. 

 Claws — Two; superior has a minute tooth about midway, in 

 some specimens this only occurs on the last pair of legs and in 

 others there is a small lateral tooth also ; inferior unarmed, 

 about one-half the length of the superior and dilated somewhat 

 at the base; tenent hair present on tibia. Ocelli — Sixteen. 

 Furcula^ — Short, not reaching the ventral tube; dentes and 



