ON THE CHILOPODA OF NORTH AMERICA. 41 



Fam. V. GEOPHILID^, Leach.* 



Segmenta numerosa, singula subsegmentis duobus completis sed insequalibus efformata, et pedum par 

 unicuni gerentia. Oculi nulli. Antennas 14 articulate. Pedes anales breves, styliformes. 



The family character of this group, which first attracts attention, is the large number 

 of segments, each of which is composed of two unequal subsegments. The boundaries 

 of the respective scuta of each pair of the latter are well marked by sutures, &c, but 

 the sterna are completely consolidated. The head varies in form, size, &c, and fur- 

 nishes the principal generic characters. The number of joints of the antennae is fixed 

 for the family, but nevertheless good specific, and even generic, characters are derivable 

 from these organs. The most important specific characters besides those before 

 alluded to are founded upon, firstly, the peculiarities as to size, shape, proportion, &c, 

 of the component portions of the head and its appendages; secondly, the color and 

 form of the body and the number of segments composing it ; thirdly, the structure of 

 legs, especially of the last pair ; and, finally, the markings and sutures of the scuta 

 and sterna. We have never had an opportunity of examining large suites of speci- 

 mens, so as to determine as to the constancy of the various characters enumerated, 

 but they probably do not vary a great deal. 



Gen. 1. MECISTOCEPHALUS, Newp.t 



Segmentum cephalicum elongatuni, angustum, latitudine plus duplo longius. Antennae approximate, 

 articulis obconicis. Subsegmentum prebasale sejunctum sed basale subbasaleque coalita. Mandibulae 

 magnse, intus denticulate. (Fig. 9.) 



M. ftjlvus, n. sp — M. fulvus, politus; capite dilute aurantiaco, punetato, pilis longis rigidis paucis; seg- 

 mento cepbalico antice truncato, postice illico angustato et vix truncato ; antennis longis, pilis longis 

 rigidis multis; labio profunde punetato, antice emarginato, medio sulco impresso; mandibulis distincte 

 punctatis, pilis rigidis paucis, quadridentatis ; segmento anali piloso; pedibus pilis longis, paribus 57. 

 fGeophilus attenuatm, Say,. Journ. Acad. Nat. Sci. 1st series, vol. ii. 



Cephalic segment scarcely narrowed at all, except at the posterior end, where it is 

 rapidly contracted, being indeed rounded off. Body slender and polished. 

 Scuto-episcutal and sterno-episternal sutures very distinct, as well as those 

 between the primitive sterna. We have found this species around Phila- 

 delphia, although not very abundantly. They appear to affect the inner 

 bark or liber of decaying logs, especially that of the locust, (Robinia pseudctr 

 cacia, L.) We have, however, occasionally observed them under stones. It Fig 9 _ 

 may possibly be Geopliilus attenuatus, but that species can never be determined from 

 Say's description. 



M. melanonotus, n. sp. — M. parvus, gracillis, dilute aurantiacus ; lineis duobus dorsalibus, latis, nigris, 

 e capite ad segmentum penultiruum ductis ; capite dense minutissimc punetato, sparse breve pilosis; 



*Linn. Trans, xi. t Proc. Zool. Soc. : Dec. 1842, p. 179. 



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