﻿34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



have had an opportunity to examine the type. The species does not 

 seem to have been mentioned in the Hterature after its estabhshment, 

 and a few supplementary notes about some details of its structure 

 may be desirable. There is only one type, a female; number of body- 

 rings: 11 -{-10+ 6 =27; telson (supra-anal plate not considered) very 

 short; length of supra-anal plate 20 percent of length of carapace; 

 width of carapace, as measured from the carina to both sides, 7.5+7.5 

 mm; nuchal organ oval, not so high as eye-tubercles, and placed be- 

 tween their hind parts, so that only a very small part of it reaches 

 farther posteriorly than these; about 35 pau-s of legs. 



Localities. — I have examined a male and two females from Davis, 

 Calif. (U.S.N.M. No, 82030), and a male and female from Lassen 

 County, Calif. (U.S.N.M. No. 9377). 



This species is not known from places other than those mentioned. 



Remarks. — I have placed in this species some California specimens 

 which belong to the group with 9.5-13 leg-bearing abdominal rings 

 and which certainly are not L. arcticus, L. couesii, or L. lemmoni. 

 Particulars are given in table 1 . They agree well with L. packardi in 

 the armature of spines on the posterior emargination of the carapace, 

 and in having only large spines on the supra-anal plate. On the other 

 hand, most of them have more spines on the supra-anal plate than 

 the type specimen, and fewer teeth on the last legless ring, but, in 

 these respects, individual variations may be expected. It is to be 

 added that L. patagonicus Berg from South America (p. 17) obviously 

 is nearly related to this species and possibly identical with it. 



LEPIDURUS COUESII Packard 



Figures 9; 11; 12; 19, h; Plates 1 (Figures 2, 3) and 7 (Figure 5) 

 Le-pidurus couesii Packard, 1875, p. 311; 1883, p. 317.— Johansen, 1921, p. 29. 

 Lepidurus macrurus Lilljeborg, 1877, p. 9. — Simon, 1886, pp. 429, 448. — Sars, 

 1897, p. 464; 1901, p. 143. 



Description. — I have examined two males and one female, marked 

 "type" (U.S.N.M. No. 11605). According to the label, they were 

 collected in Montana by E. Coues, as were Packard's type specimens, 

 and I think there is no doubt about their being true types. Further, 

 I have seen two males from Montana in the Stockholm Natural 

 History Museum that were sent from Packard and thus, with som.e 

 justification, ought to be regarded as types, too. 



It appears from these specimens and from seven others from North 

 America (table 1) that L. couesii is easily distinguished from other 

 North American species of the genus. The number of rings is 11 + 

 (9.5-11.5) + (4-5.5) = 25-27. The nuchal organ has its front part 

 placed between the hind part of the eye-tubercles. The supra- 

 antennal crest is quite smooth. 



It is often mentioned as a good character of this species that the 

 supra-anal plate is unusually long. This certainly is true of the 



