332 Mr. R. V. Chamberlin on new 



Mecistocephalus medius, sp. n. 

 (PI. XL figs. 5-11.) 



Dorsum fulvous, of slight ferruginous tinge. Legs fulvous. 

 Head and prehensorial segment chestnut. 



Head widest anteriorly, the sides moderately converging 

 caudad, more strongly so adjacent to posterior corners. 

 Anterior margin widely rounded. Posterior margin broad, 

 slightly bowed (PI. XL fig. 5). Head in type 1*68 times 

 longer than wide. 



Median piece of labrum broadly sublanceolate. Anterior 

 margin of lateral pieces, when projected to meet forming a 

 straight line at middle, curving caudad of ectad at outer 

 ends. Free margins of lateral pieces concave in ectal 

 region, convex mesad of middle, with mesal angles as shown 

 in PI. XL fig. 7. Anterior pieces only a little narrower at 

 mesal ends than at the ectal. 



Areolated area of clypeus much longer than the non- 

 areolated posterior paired bands. Median dividing band 

 rather wide. Sublateral teetli as shown in PL XL fig. 6. 



Mandible with seven lamellae, counting the much reduced 

 ectal one. First lamella with five characteristic^ I}' long 

 teeth (PI. XL fig. 9). Median lamella with about fifteen 

 teeth, all long, the proximal ones more loosely arranged. 



Areolated area of coxosternum of second maxillae large, 

 the median band very broad. Pores narrowly subeliiptic. 

 Ectal corners of coxae of first maxilla? only slightly elevated, 

 rounded. Setae of maxillae as shown in figure. Distal joint 

 of palpus characteristicallv bluntly rounded, the claw much 

 reduced (PI. XL fig. 8). 



Teeth on anterior margin of prosternum very small. 

 Claw of prehensors exceptionally slender, tooth at base 

 prominent. Femuroid with the usual two teeth, of which 

 the distal is the larger and projects distad of mesad. The 

 succeeding joint bears no tooth, but the next one bears 

 a prominent tooth at its distal edge, which projects distad 

 of mesad (PI. XL fig. 10). 



Impressions of anterior sternites furcate, the branches 

 forming an obtuse angle (PL XL l\g. 11). 



Posterior portion of body of type missing, hence the total 

 length and the number of segments cannot be given. 



Width of first tergite 1*2 mm. 



Locality. — Solomon Is.: Ngi [W. M. Mann). 



Type in Mus. Comp. Zool. at Cambridge, Mass. 



