OF CARBONIFEROUS MYRIAPODS. 285 



remarkable than the occurrence, apparently so near the origin of the type to which it 

 belongs, of ornamentation of such excessive delicacy, finish, complication and regularity. 

 I cannot discover that dermal appendages of such delicate and specialized organization 

 occur anywhere to-day among arthropods, unless it be when developed as scales, 

 as in Lepidoptera, and occasionally in other groups of hexapods ; some chaetopod worms 

 have indeed hairs of curious asymmetrical structure, often very delicate and somewhat 

 specialized, but never, so far as 1 can learn, to nearly so high a degree as here. The col- 

 lection of these rods into fascicles is also not a little curious, and is again a feature known 

 now in arthropods only in a few instances, such as some tufts of hairs in lepidopterous cater- 

 pillars like Orgyia ; or the pencils of hair-like scales in the males of some perfect Lepidop- 

 tera, e. g. at. the tip of the abdomen in Heliconia, Danais, Agrotis, Leucarctia, etc. ; or in 

 the terminal fascicles of barbed bristles in the myriapodan genus Polyxenus. 1 



There is no group of animals into which such a jointed creature as this could fall except- 

 ing worms, myriapods, or the larvae of hexapod insects. The certainty that this animal 

 possessed a single pair of well developed legs of identical character on every segment of 

 the body behind the first segment or head is of itself sufficient evidence to exclude it both 

 from the worms and from the larvae of hexapod insects. No such legs or leg-like struc- 

 tures occur tc-day in worms, and it would be idle to look for them in their ancestors of car- 

 boniferous times. The only approach to such an appearance in hexapod larvae is in the 

 young of tenthredinous Hymenoptera, where, however, a difference of great morphological 

 significance is found between the true or thoracic legs and the pro-legs or those attached 

 to the abdomen; a difference based on one of the most essential underlying features of 

 their structure as hexapods. No such difference occurs in Palaeocampa, and it is, therefore, 

 impossible to conceive of it as the larva of a hexapod insect of any sort. 2 



In myriapods only do we find a repetition of legs of exactly similar structure on every 

 or nearly every segment of the body; 3 by this test Palaeocampa is a myriapod ; and now 

 that we have found ancient types of this group, like the Archipolypoda, bearing huge and 

 bristling spines arranged in series along the sides of the body, we need not be at all dis- 

 concerted at discovering this new type, with longitudinal series of fascicles of stiff rods, al- 

 though we cannot restrain our surprise and admiration at their exquisite intricate structure. 



Accepting Palaeocampa then as a myriapod, we may next ask what relation it bore to 

 the myriapods of the same period and found in the same waters, and also to myriapods of 

 to-day. 



The differences between the stout, forked and bristling spines of the Archipolypoda and 

 the close-set but spreading bunches of highly organized stiff rods of Palaeocampa appear 

 upon the. barest statement. Were it not, however, for the complicated ornamentation of 



1 See Proc. Bosl. Sue. Nut. His/., xxil, 66, li^'s. American Journal of Sen na . the author supports by no facts 



- Dr. Packard lias recently remarked (Proc. Amer. Phil. beyond what are implied in the above quotation. How he 



Soc. xxi, 'Jus) : •■[! seems to us that the larvae of the neurop- wil1 account for the unquestionably close relationship of Pa- 



terous Panorpidae, with their two jointed abdominal prop- laeocampa, Trichiulus, and Euphoberia does not yet. appear. 



legs, small head and singularly large spinose spines, arising 3 Some smaller groups, formerly, and by some authors still, 



in groups from a tubircle or mammilla, come nearer to Pa- considered as belongingtot.be myriapods, must be excepted 



laeocampa than any myriapod with which science is ac- from this statement; their relation to Palaeocampa will be 



quainted." This opinion, expressed since this paper was writ- discussed further on. 

 ten and since the publication of my general results in the 



