mm 
. 
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 63 
forming a truncated angular spine, and not much more than half as long as the outer lamina; between the inner 
and outer lamina, its base next to the inner lamina, is a middle spine ending in an irregular tuft of fine spinules. 
The genus is distinguished from Trichopetalum by its want of eyes, its broader head, its long slender body, 
with long set®, by the eighth pair of female rudimentary legs ending in a claw. From Zygonopns it differs in the 
shorter sixth antennal joint, its broader head, its slenderer legs, the sixth pair in the female not being unlike the 
others, and by the more prominent shoulders and longer set®. The species of the two genera are of the same general 
form and size. 
The genus Scoterpes was proposed by Professor Cope for the present species in the American Naturalist for July, 
1872, page 414. The very brief and incomplete characters given are the “ lack of eyes and of lateral pores; ” the 
absence of the latter having been “asserted by Dr. Packard.” Ignorant of the difference between the Mammoth 
Cave blind Myriopod and Lysiopetalum, the latter being the only genus of the family then known, we referred it to 
the genus Spirostrephon. 
^—-•Scoterpes copei Cope. Plate VIII, figs. 1, la-1 m. 
Spirostrephon (Pseudotremia) copei Packard, Amer. Naturalist, v, 748. December, 1871. 
Scoterpes copei Cope, Amer. Naturalist, vi, 414, July, 1872. 
Spirostrephon copei Harger, Amer. Journ. Sci., iv, August, 1872. 
Spirostrephon copei Packard, Zoology, edit. 1-3, 1879~’81. 
Scoterpes copei Pack., Proc. Amer. Phil. Soe., xxi, 193, 1883. 
About twenty males and females examined. Body white, with no dusky discolorations ; thirty segments besides 
the head in specimens 11 ™ j rl length; and fifty-two pairs of legs; in one female individual 8 mm long there were 
forty-nine pairs of legs, including the eighth or rudimentary pair; in other individuals 6 mm long there were twenty-four 
segments behind the head. The head is provided with short, fine, erect hairs of different lengths, especially on the 
sides of the gen®. In the absence of a second species we can not distinguish all the specific from the generic char¬ 
acters. For minor specific characters the reader is referred to the figures. 
The males and females are alike in size and form. 
The specimens were most abundant in the Labyrinth in Mammoth Cave, but also occurred in other localities in 
the cave. It is also common in Diamond Cave, where I collected it, and was discovered by Mr. Sanborn in Poynter’s 
Cave, 300 yards from daylight. In one of the specimens from the last-mentioned cave the antenn® were rather more * 
slender than usual. 
The genus Scoterpes and its single species copei appears to be limited to Mammoth Cave and the others near, in 
apparently the same system of caves. It was erroneously reported by me to occur in Weyer’s and the Luray caves, as 
the specimens collected belong to Zygonopus whitei. Without doubt the genus is a modified Trichopetalum, which has 
become longer and slenderer in body, with longer legs and antenn®, as well as set®; whether it is a descendant of 
Trichopetalum lunatum or not is uncertain; it may have descended, from a different species, but there seems to be no 
reasonable doubt but that io is a modified form of a small hairy Lysiopetaloid form, with antenn® exactly like those 
of Trichopetalum. (For details of which genus see Plate VII, figs. 2, 2a-2/.) 
Zygonopus Ryder. 
Zygonopus Ryder, Proc. U. S. Nat. Mus., iii, 527, February 16, 1881. 
Zygonopus Pack., Proc. Amer. Phil. Soc., xxi, 194, 1883. ' 
Body rather slenderer than in Scoterpes. The head differs from that of Scoterpes in being much narrower and 
higher, the swollen sides or gen® being much less swollen; the vertex is swollen; the front as broad as long, with the 
upper edge a little hollowed, but quite distinct from the vertex itself. The eyes entirely wanting, as in Scoterpes. 
The antenn® are rather thick, and in this respect approach Scoterpes, butthe sixth and seventh joints are much longer 
and rather more setose; the sixth joint is about two-thirds as thick as long, and the last (seventh) joint nearly twice 
as long as thick. The sides of the segments are swollen subdorsally as in Scoterpes, and the setiferous tubercles are 
arranged as in that genus, but the set®, are shorter; the lower posterior edges of the arthromeres below the shoulder 
or hump is chased obliquely with fine impressed lines. The feet are less in number than in Scoterpes. The diagnostic 
characters of the genus lie in the remarkably swollen sixth pair of feet of the male, in which the second joint is rather 
thick, while the third joint is long, and with the fourth joint remarkably swollen, with a series of about nine oblique 
retractor muscles diverging from the proximal end of the terminal joint, which is long and slender and straight, with a 
well-developed claw. The seventh pair of the male are of the normal form. The rudimentary or eighth pair are like 
those of Trichopetalum, the second (terminal) joint not ending in a claw, thus differing from those of-Scoterpes. The 
male genital armature is entirely unlike that of Scoterpes, though it is rudimentary and minute; the outer lamina 
consists of a basal subtriangular portion, ending in a long, slender, curved spine, beneath which is a stouter spine, 
shorter and less curved; a minute median setose lamina is present, while the inner lamina is a weak, slender, setose 
filamentary outgrowth. 
Mr. Ryder’s generic characters are stated very briefly, as follows: “ Sixth pair of legs very robust, and with the 
third joint greatly swollen.” The generic characters are not contrasted by him with those of Scoterpes. 
This genus differs from Scoterpes in the remarkably swollen, clasping, sixth pair of legs and in the male genital 
armature, while either sex differs from Scoterpes in the much narrower head and longer sixth and seventh antennal 
joints. 
