20'6 



SCIEXCE- G OS SIP. 



AN INTRODUCTION TO BRITISH SPIDERS. 



By Frank Percy Smith. 



(Continued from page 167.) « 



FAMILY THERIDIIDAE. 



TT"E now come to a family of spiders which is at 

 ' ' once the largest and most difficult to elucidate. 

 Numbers of the species are extremely minute ; and 

 whilst many are very distinct, others are so much 

 alike that they can only be separated with great 

 difficulty. In numerous cases descriptions without 

 accurate drawings are almost useless for purposes of 

 identification. In treating of this family it will be 

 advisable to omit certain species. Some have been 

 described with insufficient accuracy to ascribe to 

 them their true systematic position, the types being 

 now unobtainable ; others are of doubtful value as 

 species, and until their distinctness has been thoroughly 

 investigated the insertion of their names in an intro- 

 duction of this kind would be misleading, as many of 

 them may have to be regarded as varieties. A few 

 species of extreme Tarity have been described, of 

 which I am unable to obtain either specimens or 

 good drawings, and these will be simply referred to 

 their discoverers. With regard to the classification, 

 I have adopted many of the numerous genera into 

 which the old Blackwallian groups have been divided, 

 but it will need much time, and an increased number 

 of workers, before anything like finality can be arrived 

 at in the Theridiidae. 



In dealing with many of the closely-allied species 

 included in this family, such descriptions as I could 

 insert in the space at my disposal would be useless 

 for purposes of determination. I shall therefore 

 endeavour as far as possible to publish drawings of 

 the palpi and vulvae of many of the best-known forms, 

 as these are in the majority of cases the most trust- 

 worthy specific characters. 



GENUS EPISINUS WLK. 



Fakes moderately long. Central eyes form a 

 quadrilateral much narrower in front than behind. 

 M axillae very slightly inclined. Posterior eyes in a 

 strongly curved fine, its convexity being directed 

 forwards. Lateral eyes slightly separated. 



Episinus truneatus Wlk. ( Theridic 

 latum BL) 



Length. Male 3 mm., female 3.5 mm. 



This not uncommon species may be easily distin- 

 guished from its allies by the curious shape of the 

 abdomen, which is narrow in front and widens con- 

 siderably toward its posterior extremity, where it is 

 steep and truncated. 



GENUS THERIDION WLK. 



Palpus of female provided with a terminal claw. 

 Maxillae inclined, usually more than twice the length 



of the labium. Central eyes forming a quadrilateral 

 figure, almost or quite as wide in front as behind. 

 Length of falces greater than height of clypeus. 



Theridion formosum Clk. (T. sisyphum Bl. ) 



Length. Male 3 mm. , female 4 mm. 



The abdomen is very convex above, and projects 

 considerably over the cephalo-thorax. The sides are 

 adorned with several oblique markings. It is not 

 common. 



Theridion sisyphium Clk. T. nervosum 

 BL) 



Length. Male 3.5 mm., female 4.5 mm. 



The abdomen of this pretty spider has two dark 

 brown longitudinal bands, which are crossed by a 

 number of narrow pale fines. It is very common. 



Theridion pictum Hahn. 



Length. Male 4 mm., female 4.5 mm. 



This very beautiful species, which is not uncommon 

 in gardens and conservatories, may be distinguished 

 at once by the dark red dentated band, bordered with 

 yellow, upon the upper side of the abdomen. 



Theridion tepidarioram Koch. 



Length. Male 5 mm., female 6 mm. 



This species may be recognised by its dull colours 

 and large size, and also by the fact that it is seldom. 

 if ever, found outside greenhouses or conservatories. 

 It is common everywhere. 



Theridion denticulatum Wlk. 



Length. Male 3 mm., female 3.5 mm. 



The upper side of the abdomen is of a grey colour, 

 with a central pale dentated band. It is common in 

 gardens. 



Theridion varians Hahn. 

 Length. Male 2.5 mm., female 3.5 mm. 

 Similar in general appearance to T. denticulatum 

 Wlk., but considerably paler. 



Theridion tinetum Wlk. 



Length. Male 2 mm. . female 2. 5 mm. 



Similar to T. varians Hahn., but considerably 

 smaller, the pale portions being suffused with gi 

 The abdominal pattern also is usually less regular. 



Theridion aulieum Koch. [T. rufolin 

 in • Spiders of Dorse:. 



Length. Male 2. 5 mm. , female 3. 5 mm. 



Cephalo-thorax dull yellow, with a central and 

 marginal band of reddish-brown. Not common. 



Theridion vittatum Koch. (T. pulchelltim 

 Wlk.) 



Length. Male 2.5 mm., female 3 mm. 



