S. annulatus.
"Body with numerous, elevated, obtuse lines, of which four are above the stigmata; ultimate segment glabrous, unarmed."
"Body cylindrical, emarginate, above brownish with a slight tint of red, immaculate, beneath yellowish white; segments each with about fifteen elevated obtuse lines, of which four are equal dorsal, a pyriform larger oblique one on the stigmata, and about ten decreasing in size to the feet, anterior segment as long as the three succeeding ones conjunctly and glabrous, posterior one glabrous reddish brown, as long as the two preceding ones, united and obtusely rounded at tip; head whitish before; antennæ white; eyes transverse linear, black; vertex not distinctly impressed."
I. annulatus, Say, Journ. A. N. S., 1st series, vol. ii, p. 103.
S. annulatus, Newport.
Species mihi ignota.
Fam. POLYDESMIDÆ.
Sterna et scuta arete conjuncta; scuta laminis lateralibus instructa.
Sterna and scuta closely cemented together; scuta furnished with lateral lamina. (Fig. 40.)
Fig. 40.
The head in the Polydesmidæ is large and massive. The absence of eyes and the small antennæ point to a state of low development of the special senses. The female genitalia are placed in the third segment, just posterior to the second pair of legs. They are
generally more or less hidden within the body. The male
organs are situated in the seventh segment, replacing the
eighth pair of legs. They generally project from the body so
as to be very prominent.
Authors generally have divided this family into genera, founded upon the size and form of the lateral lamina. But, as H. De Saussure (loc. cit.) has remarked, these characters are relative, and the differences so merge into one another that the groups cannot be well defined or separated by distinct border lines. He therefore has very properly adopted these groups as subgenera. Fontaria, he thinks, has more claims as a distinct genus than the others, but even this is scarcely worthy of the higher rank. He takes for his generic characters the position and numbers of the lateral pores. In this I have followed without feeling sure but that at some future time still better characters will be elucidated. Two forms herein described apparently do not belong in the
