156 



NATURAL HISTORY. 



lines. Both these species are common in Britain and most parts of Europe. Some British 

 and European species are considerably larger than these, but the giants of the family are to 



be sought within the ti-opics, species of the 

 genera Spirostreptus and Spirobolus inhabiting 

 India, Africa, tropical America, and the West 

 Indies, attaining a length of from six to nine 

 or ten inches. All the species have the power 

 of rolling themselves up into a spiral form 

 with the legs concealed. 



FAMILY IT. POLYDESMIDJE. 

 These animals are very nearly related to 

 the preceding, but although the dorsal plate 

 is continued on to the ventral surface, it is 



JULTJS TERRESTRIS. generally furnished with a dilatation at the 



sides, and the insertions of the limbs are 

 In general habits they resemble the Julidse, and are chiefly 

 They generally have no eyes, and the 



separated by a distinct sternal piece. 



found under bark, where they are often abundant. 



number of segments is twenty ; they are also more or less depressed, and thus present a general 



resemblance to the Scolopendridse. 



FAMILY III. SIPHONIZANTIA. 



This is another family allied to the Julidse, but differing from it in more important characters 

 than the preceding. The body is semi-cylindrical, and the dorsal plates of the segments encroach 

 only a little upon the under surface. The head is small, and concealed beneath the margin of the first 

 segment; and the clypeus in combination with the organs of the mouth, which are united, forms 

 a sort of conical sucking organ. The legs are short, and do not project beyond the sides of the body. 

 The species, which are few in number, are of comparatively small size, but consist of numerous 

 very short segments. They are found in rotten stumps of trees. One species (Polyzonium germani- 

 cum), about half an inch long, is found on the continent of Europe, especially in Germany and 

 Poland. The rest are for the most part exotic. 



FAMILY IV.-GLOMERID^]. 



The Glomeridse are short ovate forms much resembling the common Wood Lice, with some of 

 which they also agree in their power of rolling themselves into a ball. They are convex above, 

 and composed of twelve or thirteen segments, of which the dorsal plates extend only to the margins, 

 within which, on the lower surface, there are pleural plates separating the dorsal plates from the 

 points of insertion of the legs. The number of pairs of legs varies between seventeen and 

 twenty-one. Several species inhabit Europe, and most of the exotic forms belong to the Eastern 

 Hemisphere. They may be compared to abbreviated Julidae, and ai'e like them in their habits. 



ORDER III. PAUROPODA. 



This order has been established for one or two curious little creatures discovered by Sir John 

 Lubbock during his investigations on the Thysanura, to which, apart from the presence of limbs on all 

 the segments, they present a considerable analogical resemblance. These little animals consist of eight 

 segments besides the head, and these segments bear a good many short and a few long bristles. The 

 head also is sprinkled with hairs. The first segment of the body has a single pair of legs, 

 while each of the following segments to the fifth bears two pairs, and may consequently be regarded as 

 double ; in fact, the divisions are recognisable beneath, and Sir John Lubbock, reckoning the head to 

 be composed of two segments, assigns fourteen primitive segments to the whole body. The most 

 remarkable character, however, is to be found in the antennse, which are five-jointed and branched, 

 with one branch terminated by a long, minutely-jointed lash ; while the other has two shorter ones, 

 between the bases of which is placed a peculiar appendage, sometimes supported on a footstalk. Such 

 a structure of the antennae reminds one rather of the Crustacea than of any air-breathing Arthropod. 



