18 ON THE CHILOPODA OF NORTH AMERICA. 



there may be species perfectly distinct, but the individuals of which may so approxi- 

 mate that there may be difficulty in placing some of them. Does the mere difficulty 

 or impossibility of placing an individual necessarily invalidate the claims of the 

 species? The moss Leucobryum glaucum, Hampe, is acknowledged by all botanists 

 (we believe) as distinct from L. minus, Hampe, the most tangible difference being that 

 the former fruits in October, the latter in May. Now we have found fruiting speci- 

 mens in April, which are undoubtedly referable to L. glaucum; but had they been 

 found a month or two later, would any botanist have hesitated in labelling them L. 

 ■minus? Indeed, one of the best American authorities told us, that had we so found 

 our specimen, he would have pronounced it to be L. minus. 



In the other genera of the Scolopendridoa the specific characters are pretty much 

 the same as in the true Scolopendra. But some characters specific in the latter, else- 

 where become generic subcharacters. 



Subfam. I. SCOLOPENDMNyE, Newp* 



Spiracula valvularia in paribus 9. 



Gen. 1.' SCOLOPENDRA, Linn. 

 Segmentum cepbalicum imbrieatum. Oeuli stemmatosi, utrinque4. Antenna; attenuate. Pedum paria21. 



S. HEROS, Girard. — S. testacea, segmento cepbalico subovato, minute punctato ; antennis 25 articulatis ; dente 

 mandibulari producto, gracile ; dentibus labialibus 8 — 10, duobus intimis utrinque plerumque coadu- 

 natis ; pedibus plerumque luteolis; paris postremi articulo basali, intus 5 — 7 spinis,f subtus 7 — 10 spinis 

 in serie triplici dispositis, processu angulari 3 — 10 spinis ; appendicibus analibus lateralibus elongatis 

 minute profunde punctatis, spinis apicalibus utrinque 5 — 7-et altero marginali. 

 S. lieros, Girard, Marcy's Report of Explorations on tbe Red River, p. 272, pi. xviii. 

 Yar. Castaneiceps, Wood, I'roc. A. N. S. 1801, p. 11. 

 S. yiridis, capite antennisque rubro-eastaneis; pedibus plerumque luteolis interdum viridibus, paris postremi 

 articulis basalibus saturate viridibus. 



Prebasilar fold connate with the basilar segment, the suture generally, however, 

 well marked, existing as a deep groove. Cephalic segment slightly emarginate be- 

 tween the antennae. Labial teeth from 8 — 10 in number; there will sometimes be 

 four on one side and five on the other, the external tooth apparently being the missing 

 one. Antenna; 2-">-jointed. Out of nearly a hundred specimens that we have examined, 

 only two or three had one or two supernumerary joints developed. Scuta polished, 

 generally minutely and sparsely punctate, often obscurely bicarinate, the posterior 

 with their lateral margins elevated. Last pair of legs rather robust, with the basal 

 joint longer than the tibial. Scuto-episcutal sutures apparent, the sterno-episternal 

 very well marked. We have seen a number of specimens from Alabama and Georgia 

 in the cabinet of the Museum of Comparative Zoology. 



* Linn. Trans, vol. six. p. M77. 



f When giving the spines on the inner edge of a leg. we do not (as some do) include those on the terminal 

 angular process, which arc afterwards given separately. 



