Page:Wood 1865 - The Myriapoda of North America.djvu/79

214 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—16—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.

The head has its anterior surface covered with numerous short rigid hairs, causing it to appear pubescent. The antennæ are rather long, pubescent, and clavate. The first scutum is transversely oval, narrower than the head. The lateral lamina are 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 triangular, with its apex somewhat prolonged and decurvate; it is shortly pilose. I 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 (Fig. 41) is swollen into a sort of knob-like process, from which 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. This 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 developed, although they have the appearance of being so. Mr. Say's description will apply