6 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Eyes present, each consisting of a single large ocellus. 



Antennae short; articles 24 to 31, but mostly 25 or 28 (in N. Amer. 

 forms); articles beyond the second short, with marked tendency for 

 shortest ones to recur in pairs. 



Prosternum conspicuously narrowed cephalad, with anterior margin 

 narrow. Teeth 2+2 or. 3+3. (Plate 1, fig. 7). 



Seven pairs of spiracles present, one pair being present on the first 

 leg-bearing segment. 



None of the dorsal plates with posterior angles produced (in N. 

 Amer. species). 



First eleven or twelve pairs of legs with tarsi entire, bearing a tibial 

 process (Plate 1, fig. 12) ; last three pairs with tarsi biarticulate and 

 tibiae without processes. Coxae of last pair of legs without caudal 

 processes. 



Coxal pores present on last four pairs of legs. 



TYPE. L. fulmcornis Meinert. 



The four species known from the United States are small forms less 

 than 19 mm. long. Males of none of them have been found. The 

 species of this genus are difficult to discriminate. . 



Key to species. 



a. Articles of antennae normally 25; first tarsal joint of anal legs 

 only about four times as long as its greatest width. l 



L. fulmcornis Meinert. 

 aa. Articles of antennae 28 (-31); first tarsal joint of anal legs eight 



times or more as long as its greatest width. 



b. Length 5 to 6.5 mm. L. timus Chamberlin. 



bb. Length at least 7 mm. 



c. Greatest thickness of femur of anal legs 1.5 times the great- 

 est thickness of tibia; antennae 3.7+ times the length of 

 head. L. pinampus Chamberlin. 



cc. Greatest thickness of femur of anal legs but 1^ times 

 greatest thickness of tibia; antennae 3.2=*= times the length 

 of head. L. pius Chamberlin. 



1 In measuring the joints of the anal legs the method uniformly followed by the 

 author has been to detach one leg and mount it with mesal surface down, measurements 

 being then made by means of an ocular micrometer. 



