Jandury — March 1SS5.' 



PSYCHE. 



247 



other things, the presence of stigmata 

 on each of the ventral scutes in diplo- 

 foda* All the carboniferous archipoly- 

 poda show a clear indication of the 

 compound nature ot the segments. Not 

 only were the \'entral scutes fai' more 

 important and extensive than in the 

 modern diplopoda^ hut some at least 

 ot the genera bore in acklition tn large 

 stigmata outside the legs, a pair of seg- 

 mental organs next the medioventral 

 line on each ventral scute ; the dorsal 

 scute was also distinctly divided into tv\ o 

 areas, an anterior and a posterior. In 

 some types this latter distinction was 

 more marked than in others, in some 

 lieing carried so far that under certain 

 conditions of preservation one would 

 readily take tiiem to be entirelv sepa- 

 rate ; and this indeed appears to be 

 absolutely the case in the older devo- 

 nian forms, from the lower old red sand- 

 stone of Scotland. These show an 

 apparently complete demarcation of the 

 dorsal scutes of each segment as well as 

 of the ventral, and present therefijre a 

 series of alternating larger and smaller 

 segments, the larger bearing all the 

 tlorsal cuticular outgrowths, but each 

 bearing a single pair of legs. Of this 

 primal condition of the Ijodv segments 

 the emliivology of modern types gives 

 no hint, its earliest indications showing 

 nothing anterior to what must have 

 been the condition of things wli(.ll\- 

 posterior to the paleozoic epoch, at least 

 so far as the diplopodan series is con- 

 cerned ; nothing anterior, indeed, to the 

 fixed condition of the present type. 



*They are only borne in a^eneral nri alternate seg- 

 ments in chilopoda. 



This indicates tlrat the present dorsal 

 scutes of diplopoda are compound and 

 formed of two originally distinct scutes ; 

 and that, as a later development of a 

 similar sort, the ventral scutes of the 

 anterior segments have likewise con- 

 solidated and lost each one pair of 

 appendages. 



Under this view the line which we 

 follow back fi'oivT the chilopoda through 

 the frotosviig'natha is tine more nearly 

 allied to the simple stock type. Yet it 

 is the other line which has been found 

 earliest in the rocks, clearly showing 

 that the actual origin of the myriopodan 

 phylum must be looked for at the very 

 first appearance of land animals ; in- 

 deed the evidence that some of the 

 carboniferous types were amphibious 

 may warrant our belief that the type 

 may have fairly originated among aqua- 

 tic animals. 



Fossil mv^riopoda were first made 

 known from the carboniferous rocks, 

 when Westwood figured, in Brodie's 

 work on the older fossil insects of 

 England, the remains of what he sup- 

 posed to be a lepidopterous larva. 

 There had been indeed earlier refer- 

 ences by name merelv to tertiary myri- 

 opoda from amber and from Aix (.Ser- 

 res), but it was not until the publications, 

 thirty years ago, of Koch, Berendt and 

 Menge, that the amber species were 

 known, and to them liardh- any ad- 

 ditions have since been made. In 

 1S59 Sir William Dawson published the 

 first account of a paleozoic m\riopod re- 

 cognized as such, and since iS6S our 

 horizon, as regards the older forms, has 

 been widened materially by the publica- 

 tions of Messrs. Dohrn, Meek and 



