374 SYNOPTIC COLLECTION. 



These spiders, notably the Lycosidae, take especial 

 care of their young. Not only are the eggs protected by 

 a cocoon, as in most spiders, but the mother Lycosa car- 

 ries the cocoon about with her until the larvae are 

 hatched. Rather than desert it, she will carry or draw it 

 after her, and will defend it to the last (Campbell). 

 McCook l records an instance of maternal ingenuity on 

 the part of one species of Lycosa (Z. tigrina) whereby a 

 nest was provided with "a window." The builder had a 

 cocoon attached to her spinnerets and she would put her- 

 self in a position to let it lie against the window where it 

 received the warm rays of the sun. For three weeks her 

 daily occupation was holding her egg-sac in the sunlight. 



When the eggs hatch, the larvae moult their first skin 

 within the cocoon. Sometimes a second skin is shed be- 

 fore the larvae get on their mother's back. She carries 

 them until the third and sometimes the fourth skin is 

 moulted, when they are able to take care of themselves. 



Among the Saltigrades is the interesting Synageks 

 picata Hentz (PI. 928), which strikingly resembles an ant. 

 This is probably a case of protective resemblance. The 

 first pair of legs extend forward and resemble antennae 

 so that only three pairs extend outwardly, although there 

 are four pairs in all, the characteristic number among 

 spiders. 



The Arachnida which are most specialized by the 

 reduction of some parts and the modification of others 

 are the mites. These are represented by several species. 

 Atax (No. 929, A. bonzi, fig. i, ventral view of larva) is a 

 water mite, living in the gills of Unio. The larva in this 

 case has the same number of feet as the adult (fig. 2, 

 dorsal view). Tetranychus (No. 930, T. telarius ; fig. i, 

 larva; fig. 2, adult) is found on plants in greenhouses, 

 while another genus, Tyroglyphus, includes the cheese 

 and sugar mites. The latter have scissors-like mandibles 



1 Amer. Spiders and their Spinning-work, III, 1893, p. 25. 



