BLACKWALL'S SPIDERS OF OREAT BRITAIN AND IRELAND. 413 



are recorded as having presented varieties ; two in Lycosa, and one 

 respectively in Dolomedes, Eresus, Salticus, Thomisus and Cinifio. 

 The number is therefore insufficient to give results of any value, but 

 it tends to confirm the usual slightly greater variability of large 

 genera. Four cases are also recorded' in which the eyes were ab- 

 normal; namely, a specimen of Lycosa cainpestris, in which the 

 lateral anterior eyes were deficient, one of L. cambrica in which the 

 right intermediate eye was wanting, a female of Thomisus bifasciatus 

 had the right posterior eye much smaller than usual, and in a female 

 of Cinifio atrox the left intermediate eye of the posterior row was 

 entirely wanting. Mr. Blackwall has only met with one other case 

 of monstrosity ; namely, a short but perfectly formed supernumerary 

 tarsus connected with the base of the tarsal joint of the right pos- 

 terior leg ; this occurred in a female of Lycosa campestris. Thus 

 four cases of monstrosity out of five occurred in the large genera, 

 and in the female sex. 



Mr. Blackwall mentions that Thomisus pallidus and one or two 

 of its congeners have " the power of changing the colour of the ante- 

 rior intermediate pair of eyes from dark red brown to pale golden- 

 yellow by a very perceptible internal motion," but it does not seem 

 clear in what manner the movement produces this effect. 



As regards the manners and customs of our spiders, it is almost 

 unnecessary to say that they are all insectivorous. Alypus sulzeri, 

 like many foreign Mygalidae, excavates a subterranean gallery, in 

 which it spins a tube of silk j the LycosidaB and Thomisida? are hunters, 

 and some species of the former are semi-aquatic, running fearlessly 

 on the surface of the water, and even sometimes descending beneath 

 it ; the Salticidse take their prey by surprise, frequently springing on 

 it from a distance ; the Drassidse " conceal themselves in silken cells, 

 " which they construct among the leaves of plants, in the crevices of 

 " rocks and walls, and under stones, and the exfoliating bark of aged 

 " trees ; they run actively in pursuit of the insects which constitute 

 " their food, or take them by surprise ; but one species, the Argy- 

 " roneta aquatica, lives habitually in the water of ditches and pools ;" 

 finally, the Cinifloridse and Agelenida? catch their prey by means of 

 curious and complicated nets. 



In the well-known circular nets of the Epeirse, the concentric 

 lines only are adhesive ; they are composed of an elastic spiral line, 

 thickly studded with minute globules of liquid gum, and Mr. Black- 

 wall has calculated, that an ordinary net fourteen or sixteen inches 

 in diameter, would contain 120,000 of these globules, in spite of 

 which the Epeira will complete its snare in less than an hour, if it is 

 not interrupted. 



" Many intelligent naturalists," says Mr. Blackwall, " entertain the opinion that 

 spiders can forcibly propel or dart out lines from the spinners : but when placed on 

 twigs set upright in glass vessels with perpendicular sides, containing a quantity of 

 water sufficient to immerse then- bases completely, all the efforts they make to effect 

 an escape uniformly prove unavailing in a still atmosphere. However, should the 



