148 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 



mucrones over twice the length of the manubrium; dentes ser- 

 rated on both edges ; mucro bidenticulate, distal tooth is slightly 

 curved and about the same length as the proximal one which 

 is curved slightly cephalad, the axes of the two teeth almost 

 parallel. Integument — Sparsely covered with short hairs. 



Variation: Tlie markings in this species are not at all 

 regular and the color varies considerably with the yellow and 

 brown predominating in some and the blue in others. There 

 was a variation in the superior claw as mentioned above; how- 

 ever, there was no variation among the specimens in each 

 locality. 



Habitat: They were found in great abundance on pools of 

 water in a newly plowed field after a hard rain ; they were asso- 

 ciated with a new species of Xenylla. Also I found them in 

 San Antonio Canyon at Camp Baldy under rocks, and in the 

 Ganesha Hills under the same condition, but they were not very 

 abundant in either of these localities. Also they were found in 

 San Dimas and Lytle Creek canyons. 



Isotoma besselsii Packard 



(Plate I, Fig. 10) 



Isotoma besselsii Packard, 1877. Explorations of the Polaris 

 Expedition to North Pole. Amer. nat. XI, 51-53. Packard, 

 1877, Amer. nat., p. 51-52 (footnote). MacGillivray, Can. ent. 

 XXIII, p. 273. Davenport, 1903, Coll. of Cold Spring Beach, 

 Cold Spring Harbor, mou. II. 1905 (Axelson) Linnanienii 

 zur Kennt. der Aptery., vol. 7, viir. Bacon, P. C. jr. ent. and 

 zool., vol. IV, pp. 813-845. 



Description: In general appearance they look almost exactly 

 like the I. hidenticula, although slightly smaller. Length — .75-1. 

 mm. Color — Brown, yellow at junction of segTuents ; furcula and 

 legs light ; ventral side dark. Antennjp — Aliout as long as head ; 

 I shortest, IV longest, II and III subequal. Ocelli — Sixteen. 

 Claws — Slightly curved; superior wide at the base but narrow 

 at the apex; inferior with inner margin dilated at the base. 

 Furcula — Short, stout, not reaching ventral tubes; manubrium 

 slightly longer than dentes; mucro tridenticulate ; distal tooth 



