S. J. McINTIRE ON THE PENCIL-TAIL. 113 



Examples of the ferocious Chilopoda are to be found in the 

 various descriptions of centipedes ; and of the vegetarian Diplo- 

 poda in the various " pill-millepedes " (or, as some call tbem, 

 " wood-lice "), the Julidse (or wire-worms of the farmer), and our 

 little friend Polyxenus. 



In common with the whole group, the Polyxenus breathes by 

 means of an extensive tracheal system. Its eyes are, I believe, 

 ten — in two groups of five in each. There are, however, on each 

 side of the head two objects, whose character I have not satisfac- 

 torily determined ; if they are eyes, the total number is fourteen. 

 The antennas are, I believe, 8 -jointed, although authorities declare 

 seven segments in these organs is the maximum number existing in 

 any of the Diplopods. It would appear that the Polyxenus is one 

 of the connecting links between the Myriapocla and the Annelids ; 

 its nearest congener in that group being Nereis, one of the marine 

 worms. 



These points, and many more bearing upon the subject, which I 

 need not dilate upon, are detailed in the paper I have alluded to 

 (Transactions of Linnean Society, Vol. xxvi.), and I recommend 

 those interested to read it.* 



A casual allusion is made in " Wood's Natural History" (Rout- 

 ledge) to Polyxenus. He says (Vol. iii., p. 696) that "it is found 

 under the bark of trees, in clefts of walls, and in moss." Dr. Gray 

 and myself found a couple under a stone at the foot of a tree near 

 Mickleham on June 24th of this year, but this was quite an excep- 

 tional case in my experience. I never before obtained any else- 

 where than on willow, apple, and elm trees, and I therefore think 

 the two specimens I allude to must have been, like so many mem- 

 bers of the Quekett Club on that day, out for an excursion when 

 we caught them. Strangely enough, too, under the same stone 

 there was a larva of Tiresias Serra, a well-known friend to some 

 of our members, owing to the ventilation of the " Hair of Dermestes" 

 question. I have often noticed the association of these two crea- 

 tures, and guessed the reason why. The Tiresias larva is carni- 

 vorous, and the Polyxenus vegetarian. Does the Tiresias feed 

 upon Polyxeni ? I must leave that question for the solution of 

 enquiring observers. In " Science Gossip" (Vol. i. p. 230) a figure 



* In another paper, by the same author, " On the generative organs and 

 formation of the egg of the Ammlosa " (Philosophical Transactions, 1861, page 

 595), there is avast amount of information also. 



