Superfamily Argiopoidea 



found. The females of the Pisauridae make an egg-sac composed 

 of a single piece, and carry it under the body, holding it by the 

 chelicerae (Fig. 683); those of the Lycosidas make one com- 

 posed of two valves, and drag it after them, attached to the 

 spinnerets. 



Our pisaurids are all wandering spiders which stalk their 

 prey, and make webs only for nurseries for their young. Certain 

 exotic species, however, spin permanent webs, like those of 

 Tegenaria; hence this family holds an intermediate position in 

 habits as well as in structure between the Agelenidas and the 

 Lycosidae. 



1 have made careful observations on the method of carrying 

 the egg-sac. A specimen of Dolomedes urinator had an egg-sac 

 beneath its body which was so large that the abdomen projected 

 but a short distance beyond it. The tips of the claws of the 

 chelicerae were inserted in the egg-sac; the palpi extended over it 

 in front, the tips of the palpi being closely applied to the lower 

 surface; and the abdomen was closely applied to it behind. The 

 sac was of a dirty brown colour, and was attached by a dragline 

 of clear white silk to the spinnerets. There was an attachment 

 disk on the egg-sac a short distance from the end of the spinnerets 

 and from this disk eight threads extended to the spinnerets, two 

 to each of the fore and middle spinnerets. Similar observations 

 were made on a specimen of Dolomedes sexpunctatus. It is 

 obvious that the attachment of the egg-sac to the spinnerets 

 aids the spider in holding it off the ground when she runs. 



As to the number of eggs laid by these spiders, one of my 

 students.. Miss E. L. Whittaker, reports that during the summer 

 of 1903 she counted the contents of 22 egg-sacs of Dolomedes. 

 The average sac was of the size of a small red cherry. The number 

 of eggs in each varied from 236 to 412; but in 18 of the 22 sacs 

 the range of variation was from 275 to 312. 



The egg-sac of Dolomedes jontanus, and perhaps also those 

 of other species, become mottled in colour a short time before 

 the spiderlings emerge. This appears to be due to a stretchin; 

 and cracking of the outer layer. Shortly before the opening oi 

 her egg-sac a female was observed pulling at the outer casing 

 with her chelicerae, but was not seen to open the sac. 



Several females of this species, each with an egg-sac, were 

 kept in confinement. None of these made a nursery until after 



602 



