13 



of those near the extremity of the tibiae, which are yellowish ; claws, 

 reddish brown, darkest toward tip. Anal cerci stout, yellowish brown, 

 dotted with dirty white, each dot at the base of a delicate hair. 



Measurements. Anterior femora, .62-inch; ant. tibiae, .68-inch; 

 middle femora, .60-inch; middle tibiae, .73-inch; posterior femora, 

 1.10 inches; post, tibiae, 1.30 inches; antennae (broken), 2.00 inches; 

 maxillary palpi, .35-inch; cerci, .18-inch; whole body, .70-inch. 



This species is one from a rich collection brought home by ]Mr. 

 Agassiz from the Pacific coast ; it was taken at Crescent City, Cali- 

 fornia, under a large stone ; only one specimen was obtained. In the 

 Mus. Comp. Zool., Cambridge. 



Raplddophora xantliostoma does not belong to the genus in which I 

 have placed it, but is the representative of one closely allied, though 

 perfectly distinct. I do not now characterize it, because I have only 

 a single male specimen to examine, insufficient to give with accuracy 

 and ftdness the characteristics of the genus in which it must eventually 

 be placed ; it will be sufiicient here to say, that it will be found to 

 difier from RJiapJudojjJwra in the more rounded front of pronotum, in 

 the more distant and globose eyes, in the very prominent and deeply 

 cleft tubercle of the vertex ; there is a marked difierence, in that all 

 the femora and tibiae are rectangular, and the edges minutely spined, 

 except the swollen portion of the posterior femora, which also par- 

 takes of this character in its posterior half ; the two anterior pair of 

 tibiae are noticeably longer than the femora, while they are equal in 

 RaphidopJwra proper -^ the anal cerci are blunt at the extremity and 

 channelled interiorly ; all three pair of coxae are carinated externally, 

 and the epimera of the thoracic segm<^nts are produced to emarginate 

 lamellae which almost overlap the basi of the coxae ; the sides of meso- 

 and metanotum are not prolonged downward below the pronotum, and 

 the lower edges of all the coxae are produced on the inner side to a 

 small dull spine. 



On placing these RhapMdoplwrce of the Pacific coast side by side 

 with those from the other side of the Rocky Mountains, one cannot 

 but be struck with the peculiar correspondences of structure seen. 

 On certain theories of the origin of species, one would instantly pre- 

 judge them to be most closely allied to R. maculata, Harris ; on the 

 contrary, by examining those parts of their structure which I have 

 mentioned in my previous comparison of macidata, stygki, and suhter- 

 ranea, it will be seen that Agassizii recalls most vividly stygia, wliile xan- 

 thostoma is most closely allied to subterranea, they being in short, repre- 

 sentative species of distinct faunae, it. Agassizii will be found closely 

 related to R. stygia in the shape of the basal joints of the antennae, 

 the terminal opening of the last joint of the maxillary palpus, in the 

 shape of the legs, in the spines of the four anterior femora, in the 

 form of the ovipositor and the spines of the inner valves, in the ab- 



