214 



TOE MYRTATODA OF NORTH AMERICA. 



posterior than the anterior. The last scutum is triangular with its apex prolonged and 

 decurvate. 



The specimens which I have examined have only eighteen segments each, exclusive of 

 the head, and of these there are lateral pores on only the 5 — 7 — 9 — 10 — 12 — 13 — 15 — 1(5 

 — 17 — as in the following species. The more obvious specific differences between this 

 species and P. granulatus, Say, are the following : The side plates are broader and closer 

 together, and much more deeply serrate on their margins. Whilst in P. granulatus the 

 squama on the scuta are more pronounced, less conical and acuminate, and never seta- 

 tipped. 



Bab. Pennsylvania. — Dr. II. C. Wood, Jr. 



Fig. 41. 



P. GRANULATUS. 



P. brunneus; scutis squamis obtusis convexis in scrie quadruplici dispositis ornaris. 



Brown, scuta ornamented with a fourfold series of obtuse, convex scales. 



P. (UlANULATUS, Say, Journ. Aead. Nat. Sci., 1st series, vol. ii, p. 107. 

 " Gcrvais, Suit, a Buflfbn, Aptercs, vol. iv, p. 104. 



The head has its anterior surface covered with numerous short rigid hairs, causing it to 

 appear pubescent. The antennae are rather long, pubescent, and clavate. The first scutum 

 is transversely oval, narrower than the head. The lateral lamina arc not very large, and 

 are separated from one another by broad intervening spaces. The anterior are deeply and 

 acutely serrate ; the "others slightly serrulate. The oval surfaces of the 

 scuta are covered with convex, obtuse tuberculoid scales, arranged in 

 four more or less regular transverse rows. The last scutum is triangu- 

 lar, with its apex somewhat prolonged and decurvate ; it is shortly 

 pilose. 1 dissected the sexual organs of the only male which has come 

 under my notice, but unfortunately the detailed description was lost at the 

 Smithsonian fire. If my memory serves me right, the proximal portion 

 of the spine is robust and very nearly straight ; its distal extremity (Pig. 41) is swollen into 

 a sort of knob-like process, from winch arise two slender curved processes, one of which is 

 slightly bifid, whilst the other is remarkable for being articulated by means of a movable 

 joint. 



All of the specimens examined have only nineteen segments, exclusive of the head, and 

 of these the eighteenth and nineteenth are without lateral pores. Tins would remove the 

 species from the genus Polydesmus (as here defined) were it certain that the specimens are 

 adults. They have been collected at different localities, but still may not be fully de- 

 veloped, although they have the appearance of being so. Mr. Say's description will apply 



