46 SUMMARY OF CURRENT RESEARCHES RELATING TO 



refractive medium (the crystalline cone), and each unit is impressed by 

 an image. 



In the eyes of scorpions, the retinal unit is represented by a group 

 of five cells, there is no crystalline cone, the image is refracted only by 

 the cuticular crystalline structure, and there is one image for the whole 

 of the retinules, each being impressed by a portion of the image re- 

 refracted by the crystalline structure. 



Sarcoptids in Wing-bones of Birds.* — E. L. Trouessart has found 

 a new species of Tyroglyphus (T. antricola), apparently living as a 

 commensal within the cavities of the wing-bones of parrots and other 

 birds. It is likely that they entered while the birds were sleeping, by 

 way of the nostrils, bronchi, lungs, and air-sacs. They probably feed 

 on inhaled spores. Among the Tyroglyphids there were carnivorous 

 mites (Cheletes rapax and G. alacer), probably feeding on the former. 



New Type of Sarcoptid.t— E. Sergent and E. L. Trouessart de- 

 scribe Mialges anchora g. et sp. n., which lays its eggs on one of the 

 Hippoboscidas (Lynchia maura), a parasite of the domestic pigeon in 

 Algeria. It is probable that the mite passes most of its life on the bird, 

 and only attacks the insect when depositing its eggs. Only the mature 

 females and the larva? have been found. The mite uses the insect's 

 blood as food. This is the first instance of a really parasitic Sarcoptid 

 being found on an insect — indeed, on a cold-blooded animal. The first 

 pair of limbs have no ambulacral sucker, but end in a double grappling- 

 organ like an anchor. 



Myriopodophilous Mites.J — Ivar Tragardh describes two new forms 

 of Antennophorinre, namely, Neomegistus julidicola and Parameyisti/s 

 con/rater, found in Natal and Zululand on Julida? belonging to the 

 genus Spirostrfiptus. He discusses the question of the various stages in 

 the life-history of the mites, and the relationships of his new genera. 

 The mites do not occur on the Julidse in the winter months. It seems 

 probable that they feed on the offensive fluid which their hosts secrete 

 during the summer. Experiments confirmed this remarkable fact. 



Acarid from Omentum of Negro.§ — A. Castellani records the dis- 

 covery of two specimens of an Acarid-like parasite, in the fat of the 

 omentum of a negro who had died of sleeping sickness. The colour is 

 dark yellowish, shape oval, palpi very short, six legs well developed, 

 apparently without hairs, each leg composed of five segments. The 

 total body length is 0*55 mm. The parasite resembles Cytoleichm 

 mrcoptoides Heguin, occurring in various internal organs in fowls. 



Scottish Hydrachnids.||— Wm. "Williamson continues his investiga- 

 tion of Scottish hydrachnids, and gives a list of 26 species collected 

 during 1906. Seven of these are new Scottish records. 



* Coniptes Rendus, cxlv. (1907) pp. 598-601. 



t C.R. Soc. Biol. Paris, lxii. (1907) pp. 443-5 (3 figs.). 



% Arkiv Zool., iii. (1907) No. 28, pp. 1-33 (1 pi., 18 figs.). 



§ Centralbl. Bakt. Parasitenk., xliii. (1907) p. 372. 



|l Trans. Edinburgh Field Nat. and Micr. Soc, 1906-7, pp. 393-4. 



