50 



MR. STANLEY HIRST ON THE 



fPenis stvongl>' curved and furnished with a spine and 

 2 ^ tubercle at the end T. cratcegi, sp, n. 



i^Penis straight or only slightly curved, the end unarmed 3. 



f Penis fairly long, the end blunt T. jpopuli C. L. Koch. 



3 



I Penis shorter and pointed at the end T. talisice, sp. n, 



(introduced species). 



i^Penis with barbs at the end 5, 



t. Penis without barbs 6. 



rClaw of first leg armed with short teeth or spines T. telarius, L. 



l^Claws of both first and second leg with teeth T. lintearius Dufour. 



f Penis strongly sinuous. Offshoots of claw of first leg 



I weak T. carpini Oudemans. 



I Penis straighter. Offshoots of claw of first leg stronger, 



spiniform T.tiliai'iu7n Hermann. 



1. Tetranychus schizopus Zaclier, 1913. 



Tetranychus schizopus Zacher, Berlin, Mitt. biol. Anst. 1913, 

 heft U, 38 & 40, text-fig. 4. 



? T. scdicis C. L. Koch, Deiitscb. Crust., Myr., Araclm. 1838, 

 heft 17, no. 18. 



Schizotetr any elms schizojms Tragardh, Stockholm Medd. Cen- 

 tralanst. Forsoksv. Jordbruksomr. 1915, vol. 109, p. 19. 



S . Penis of the same type as in the species found on the 

 hawthorn {T. cratcegi), being curved when viewed laterally, and 

 with one of the terminal barbs greatly elongated so as to form a 

 spine, whilst the other is in the form of a minute inconspicuous 

 tubercle, 



Paljj. Terminal finger or cone of palp apparently absent in the 

 male of this species. Dorsal sensory finger well develojDed (see 

 text-fig. 3 1 & 2, for the explanation of these terms). 



Claws of all the legs bifurcated, the two branches into which 

 the first leg is divided being in this sex split again for a short 

 distance at the tip. 



$ . Palp. Terminal finger of palp well developed and fairly 

 stout, being about as long as or longer than the neighbouring 

 rod-like setae. Dorsal sensory finger normal in appearance. 



The claws of the legs do not end as fine hairs as in the female 

 of T. telarius (and all othei' species of the genus seen by the 

 author), being divided to form two prongs or claws as in the 

 male, but the prongs of the first legs are entire instead of being 

 split again at the extreme tip as in the male sex. 



Colour rather variable, greenish, pale yellow, reddish, and 

 orange-red specimens being met with. Small dark patches are 

 sometimes present on the dorsum. 



Eggs sometimes pale amber in colour, sometimes reddish. 



Length of male (including mandibular plate) 340 /x, of female 

 350-535 /X. 



Host plants. Various species of willows. 



