MUSEUM OF COMPARATIVE ZOOLOGY. 373 



Body smooth, without dorsal spines or teeth. Eyes nearly round. Epi- 

 mera of .first four thoracic segments quadrilateral, lower angles rounded. 

 Infero-posterior angles of first three abdominal segments hardly produced 

 backward. Telson entire. 



About ten segments in flagellum of first antennae. Second antenna con- 

 siderably longer than first antenna, equal to about a third the distance from 

 forehead to the end of the abdominal stylets. Carpopodite of second pair of 

 legs produced downward between the meropodite and propodite ; propodite 

 swollen ; palm convex, setiferous, with a prominence at its base, against which 

 the tip of the dactylopodite closes ; dactylopodite curved, closing against 

 the palm throughout its whole length. Fifth, sixth, and seventh thoracic 

 legs short, with large basipodites lightly serrate on their hind border. Fifth 

 pair much shorter than the sixth and seventh, which are of about equal 

 length. The seventh pair, when stretched backward, reach to the end of 

 the telson. Many parts of the body display a coppery lustre. 



In the female, the propodite of the second pair is long and narrow, not 

 broader than the carpopodite ; the carpopodite has but a short blunt process 

 at its lower angle in place of the long projection in the male. Length of 

 body, 9 mm to ll mm - About twenty-four specimens, particular locality not 

 preserved. 



This is a stout species, resembling the last described, but differing in the 

 shape of the propodite of second thoracic legs, want of dorsal teeth, efcc. 



Allorchestes dentatus, var. inermis. 



Hyalclla dcntata, Smith, Rep. U. S. Fish Comm. for 1872 and 1873, p. 647, 



1874. 

 Hyalclla inermis, Smith, Rep. U. S. Geogr. Geolog. Survey of Colorado for 1873, 



p. 609, 1874. 



Fig. 35. 



Allorchestes dentatus, Tar. inermis, male (nat. s. 6mni.). 

 Six specimens were taken from the shallow water of the " Marjal," a marshy 

 tract on the western side of the lake, overflowed during a part of the year. 



