MYRIAPODA 65 



Body robust, less than eight times as long as broad ; legs short, en- 

 tirely concealed by the body from above ; anterior legs of male 

 with third joint normal and shorter than the second. 



Genus Tylobolus. 

 Tylobolus gen. nov. 



Type, Tylobolus deses sp. nov., from California. 



Antennae accommodated by a deep excavation in the head and 

 mandibulary stipe ; not concealed under the first segment. 



First segment scarcely emarginate on each side in front to accom- 

 modate the prominent posterior corner of the head. 



Second segment below on each side with a thick oblique ventral 

 ridge or keel enlarged in front into a rounded process projecting below 

 the corner of the first segment as a stout rounded corner. 



Segments with a very slight transverse constriction, the posterior sub- 

 segment scarcely thicker or more convex than the anterior ; repugna- 

 torial pores located in the constriction ; posterior subsegments with a 

 short and indistinct longitudinal groove behind the pore. 



Anal valves prominent and swollen near the margins. 



Males with coxa of the third leg produced into a large hook, directed 

 forward ; coxa of fourth leg prominent, the others scarcely so. 



Gonapods with ventral plate broadly triangular or rounded ; anterior 

 lobes blunt, tuberculate on the anterior face mesad. Posterior gonapods 

 rather simple, strongly curved, ending in a cylindrical pilose spine. 

 The ventral rim of the seventh segment is low, as in Arctobolus. 



TYLOBOLUS DESES sp. nov. 



(pi. in, figs. 3-3>5.) 



Type. No. 796, U. S. Nat. Mus. Collected in California by Mr. 

 Carl F. Baker. 



Related to Tylobolus hebes (Bollman) , but the body smaller, less 

 robust, and more gradually narrowed caudad, and the apex of the 

 posterior gonapods slender. 



Length of males about 40 mm. ; width 5 to 5.5 mm. ; length of 

 females 45 to 50 mm. ; diameter 6 to 6.5. Segments 44 to 46. 



mm. broad, with 55 segments. Color very dark, dull green, the posterior mar- 

 gins of the segments banded with dull red ; legs uniform deep red. The first 

 two pairs of legs are strongly crassate in the male and the coxae of pairs 3 to 7 

 are produced ventrad, but lack the larger hooked processes found in Tylobolus. 

 The present species is abundant in favorable locations in central New York. 

 It differs from the more southern Arctobolus marginatus (Say) in the smaller 

 size, more slender body, more uniform and darker color, and in the more dis- 

 tinct punctation of the surface of the segments. The basal joint of the gonapod 

 is sinuate or emarginate laterad, instead of evenly convex as in A. marginatus. 



