Pomona Coi.i.koe Joins-Ai. ok F.SToMoi.otiv 653 



scntttrcd ovit tlic rutin- siirfai'c. Anal lcj;s with six articlfs distad of llic 

 coxopli-iiriv. 



Mrfistdrrphaliix is tin- only Nortli Anicrican fjfcnus of tlir family at present 

 known. 



Genus Mecistocephalus Newport 



In this (jenus the head is very large with the cephalic lamina mueh lon){er 

 than wide and uniformly narrowed from tin- front eaudad. The nntennu- are 

 rather larp- and are a little attenuated from the proximal and distad. The lahruin 

 has till' middle piece very narrow and acutely |)ointed distad while the side pieei-s 

 hear a frinj;e of very sliorl pectinii'. In the first maxillie the branches are 

 menihranous distad. Anal legs without claws. 



So far as known the number of legs is invariable for each species. 



In California there are two species of this genus, .V. limalux Wood and M. 

 itnomalus Chamberlin, which arc easily separated on the basis of the number of 

 pairs of legs, the fi>rmer h.iving forty-five and the Latter forty-one pairs. 



Mecistocephalus limatus Wood 



This is one of the connnonest members of the Geopliiloide.i in the eentr.il 

 portion of the state and also ranges to the southern portion, though it is not often 

 iiut with during the dry season. During the rainy months it often occurs in great 

 numbers under the fallen leaves of wooded areas. It seems to be especially 

 abundant about San Francisco Bay 



A large robust species often attaining a length of (io nun. or more, while 

 the head as a whole may be "i.'i to nearly .S unn. across in large individuals. The 

 body is conspicuously attenuated from the head eaudad. The head and body are 

 polished shining. Head and antennie dark reddish or chestnut in color; body and 

 legs orange or rusty yellow, the dorsal scuta, especially on anterior portion of 

 body, often with a narrow dark band along caudal edges. Antennae long, atten- 

 uated distad. The claws of the preliensors when closed extend nearly to the 

 distal end of the first antennal article, each prehensor armed with four strongly 

 ehitinized teeth, one on each article, of which those of the first article and claw 

 are largest. Anterior sterna with a deep longitudinal median sulcus which 

 becomes less strongly developed eaudad. First spiracle much larger than the 

 second, vertically elliptical, the others circular or nearly so. Last ventral plate 

 strongly narrowed eaudad, triangular. Coxopleura of last segment with numerous 

 small pores and usually one larger one distributed over most of the surface, the 

 number few in inmiature individuals. Pairs of legs in lM>th sexes, so far as 

 observed invariably forty-five. 



Specimens have been examined from the following localities: Mill Valley, 

 Sausalito, Herkeley (author); Stanford (Mann); and Claremont (Pomona College 

 collection). 



Mecistocephalus anomalus C'liamherliii 



This species in size, coloration and geniral structure is very close to the 

 preceding one. It is readily sep.ir.-ited in h.-iving inv.iri.ilily forty-on<- pairs of 



