118 BULLETIN 168, UNITED STATES NATIONAL MUSEUM 



on the anterior region of the mesonotum and of the metanotum and 

 the posterior regions of the abdominal segments, becoming longest 

 and most numerous near the posterior end of the abdomen. Serrate 

 setae occur also on the coxae and the furcula. Length, 1.8 mm. 



Remarks. — This redescription of tridentata, still incomplete, is from 

 two cotypes: A poor specimen in the Museum of Comparative Zool- 

 ogy, Cambridge, Mass., and one lacking legs and furcula that was 

 given to me by Dr. MacGiUivray. 



Distribution. — Recorded as follows: 

 Virginia: Fredericksburg, W. D. Richardson (Museum of Comparative Zoology) . 



ISOTOMA ASPERA Bacon 



Plate 39, Figxtres 455, 456 

 Isotoma aspera Bacon, 1914, p. 149. 



Description: Length — 1.5 mm. Color — Great variation, dirty white with no 

 markings to mottled gray. Antennae — Longer than head, IV longest and thick- 

 est, II and III subequal, I little shorter than II and III. Ocelli — Widely sepa- 

 rated, sixteen. Postantennal organ — Elliptical with a rim. Claws — Two; 

 superior armed with two teeth on the inner margin, and two teeth on the outer 

 margin; inferior, wide and stout, curved on the inner margin. Furcula — Does 

 not reach ventral tube; dentes nearly three times manubrium; mucrones short and 

 curving, tridenticulate, second and third teeth opposite. Integument — Very 

 hairy. 



Variation: The color varies a great deal. 



Habitat: Camp Baldy, altitude 4700 feet, March. Lytle Creek, April; San 

 Dimas, left fork. 



Remarks. — Not having seen this species, I have simply copied the 

 original description and figures. The species evidently resembles 

 viridis Bourlet very closely. 



Distribution. — Recorded as follows: 



California: Claremont-Laguna region, G. A. Bacon. 



PROISOTOMA LAGUNA. new name 



Plate 39, Figures 457-461 



Isotoma bidenticula Bacon, 1912, p. 842; 1914, p. 147. 



Description. — Dark, dull brown, mottled; intersegmental bands 

 narrow, pale; sternum dark; legs and fm'cula pale. Eyes (pi. 39, 

 fig. 457) eight on each side, the two inner proximal eyes much smaller 

 than the others. Postantennal organ (pi. 39, fig. 458) subelliptical. 

 Antennae one-fourth longer than the head, with segments in relative 

 lengths about as 3:4:4:5. Third and fourth urotergites subequal in 

 length, or third slightly shorter (as 1 : 11 ) . Genital and anal segments 

 not ankylosed. Unguis (pi. 39, fi.g. 459) strongly curving, untoothed. 

 Unguiculus relatively large, sublanceolate, acute, extending as far as 

 the unguis. Furcula short, not attaining the ventral tube. Manu- 

 brium longer than dentes (as 6:5). Dentes subcylindrical, rounded 



