THE HARVEST SPIDERS 3205 



ing a small oval or spherical protective cell at the time of egg laying, or for purposes 

 of hibernation, or molting. A species of Chelifer has been observed to build a cell, 

 in the first instance, when preparing to molt, and in this receptacle it stayed for 

 five days, until the new integument had acquired its normal strength. But about 

 three months afterward it returned to the same quarters to spend the winter. As a 

 rule these cells, or cocoons, are left uncovered, attached to the under sides of stones, 

 etc. , but the Alpine Obisium jugorum covers its case with pieces of earth and of vege- 

 table debris. Like the majority of the class, false scorpions are oviparous; the num- 

 ber of eggs rarely exceeding fifty, although these are of relatively large size. By 

 means of a gummy material, the eggs stick together into a rounded or oval mass, 

 which remains adhering to the ventral surface of the abdomen of the female. The 

 young stay with their parent until they have acquired their definite form, but, when 

 first hatched, show no signs of segmentation, either of the body or limbs, and the 

 abdomen, which is folded against the lower surface of the cephalothorax, bears 

 rudiments of four pairs of appendages, which subsequently disappear. The only 

 fossil remains of the group hitherto discovered occur in the Tertiary amber beds of 

 the Baltic; the species being apparently generically identical with those existing at 

 the present time. 



THE HARVEST SPIDERS Order OPIUONES 



Although the members of this group are frequently compounded with the true 

 spiders, yet, as in the case of the scorpions and false scorpions, the resemblances 

 between the harvest spiders and the true spiders are comparatively few and super- 

 ficial, while the distinctive characteristics are many and deep seated. In the first 

 place, the body is oval, and the abdomen, which is united throughout its length 

 with the cephalothorax, is, as in the scorpions^and false scorpions, composed of 

 from three to eight segments. The carapace which is short, unjointed, and usually 

 bears one pair of eyes, is sometimes fused with the anterior segments of the abdomen; 

 while in some cases the dorsal plates of all the abdominal segments are united to 

 one another and to the carapace to form a single large plate, its separate elements 

 being merely defined by shallow grooves. The lower surface of the carapace is 

 either almost wholly covered by a forward prolongation of the sterna of the 

 anterior abdominal segments, or by the ingrowth of the coxae of the appendages. 

 The mandibles are composed of three segments, and are always pincer-like, and 

 sometimes very powerfully developed. The appendages of the second pair 

 (maxilla and palpus) consist of six segments, and are never chelate, although in 

 some species they, are armed with spines, and the claw is much enlarged and capable 

 of being folded back upon the tarsus. In these species the appendage is used as an 

 organ of attack and defense. The four pairs of legs are alike in form and function, 

 being used for locomotion. In addition to the mandibles and maxillae, there are 

 often accessory mouth parts, taking the form of masticating lobes on the maxillae 

 and the coxae of the first and second pairs of legs; while above the mouth there is 

 frequently a labrum, or upper lip, and above this a second piece, or clypeus. As 



