ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 199 



5. Aracbnida. 



Palpar Organ of Male Spiders. — W. M. Barrows {Proc. Amer. 

 Soc. Zool. in Anat. Record, 1020, 17, 351). The palpar organ is a 

 hjpertropbied terminal claw or dactylus. Before the last moult of the 

 male spider, the gland which secretes the claw is pulled back toward 

 the centre of the tarsus by the attached muscles, which then degeneratCo. 

 The mass of gland cells which now forms the foundation of the palpar 

 organ develops an inner tube by tlie invagination of cells from the tip. 

 In its cramped position the claw twists on itself, developing variously 

 shaped teeth which usually correspond with unmodified teeth on the 

 female claw. The muscles working the claw or palpar organ appear to 

 degenerate and to be replaced by a new set after each moult. 



J. A. T. 



Injurious Arachnids and Myriopods. — Stanley Hirst {Species of 

 Arachnida and Myriopoda Injurious to Man, British Museum {Natural 

 History) Fublicafions, 1917, Economic Series, No. 6, 1-60, 2G figs.). 

 An excellent account of spiders, scorpions, ticks, and mites which are 

 directly or indirectly injurious to man. AVe may note Holothyrus 

 coccinella, a mite which secretes an irritant poisonous fluid ; Oytoleichus 

 hominis, an acarid found by Castellani in the body of a negro in Uganda ; 

 Rhizoglyphus parasiticus, causing *' water itch " on the feet of coolies 

 employed in tea-gardens in Assam ; the carnivorous mite Fedicidoides 

 ventricosus, causing " grain itch " on men handling cotton-seed ; Nephro- 

 phagus sanyuinarius, a mite found dead day after day for a week or 

 more in the urine of a Japanese. There are some other very interesting 

 forms dealt with which are not very generally known. J. A. T, 



Behaviour of Sexes in Ixodidse.— George H. F. Nuttall 

 {Parasitology, 1919, 11, 394-404). The males of Amblyomma helrseum 

 anchor immediately when placed in a hungry state upon the host 

 (scrotum of a ram), but females will not do so in the absence of 

 previously anchored males. After the males are fed for some days they 

 show sexual excitement ; without releasing their mouth-parts they seize 

 females that chance to come near. To copulate they must release their 

 mouth-parts. After feeding for two to eight days the females wander 

 and are seized by males. The ventral surfaces are apposed, and the 

 female proceeds to feed, puncturing the skin of the host with her 

 mouth-parts, in close proximity to those of the male. Copulation takes 

 place in due course, the male temporarily removing his mouth-parts 

 from the host for the purpose. A male may copulate with several 

 females. A female may seek two males in succession. Females feed 

 very slowly in the absence of males. They gorge rapidly when fertilized, 

 and, when fully gorged, usually abandon the host without delay. 



The males of Hyalomma segyptium anchor immediately when placed 

 on the same host. In the absence of females they remain fixed or 

 change very slightly. They are excited by the close proximity of 

 females. The females do not as a rule change their anchorage 

 from start to finish ; the males seek them out. The sexes of Rhipi^ 



