748 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Interesting New Mite.* — Herr L. Karpelles discusses a new species 

 of mite (Tarsonemus intectus) whicli occurs on barley, and seems to have 

 been imported from Bulgaria to the neighbourhood of Budapest. It has a 

 twofold interest, in the first place as the cause of skin irritation and erup- 

 tion upon the workers ; in the second place, because the author has discovered 

 the sexually mature forms, never before seen in this genus of pseudo- 

 parasites. 



The diagnosis of the species is as follows : — Body spindle-shaped, with 

 a process behind the transverse groove in the male. The dorsal shield 

 never extends over the ventral surface, except on the head of the female. 

 All stages have a well-developed fourth pair of feet. The first joint of the 

 third pair of appendages on the male bears two protuberances. In the male 

 the first, in the female the second pair of feet bears an attaching lobe, 

 which is smaller than that on the other legs. 



Herr Karpelles draws the following general conclusions from his study 

 of this mite : — (1) The mites previously described as species of Tarsonemus 

 are really so, in spite of Haller's opinion. (2) Among these there may 

 have been sexually mature forms, since the external genital organs of 

 the female are not noticeable, and since those of the male, hitherto over- 

 looked, are protrusible structures situated on the two last segments. 

 (3) Presence or absence of tracheae in parasitic Acarids is not a character 

 of much import. (4) Dermaleichidae, with the much modified Listropho- 

 ri^iae and Myocoptidse are the nearest relations of the genus Tarsonemus, 

 which appears to unite them with Myohia. (5) The male of Tarsonemus is 

 not only the more persistent form, but that which, on account of the 

 structure of its fourth pair of legs, is more especially parasitic. As the 

 oral structures of both sexes are similar, the above pair of appendages 

 must be of most importance in causing the skin eruption on man. 

 (6) Berlese notes Tarsonemus to illustrate his statement that dimorphism 

 should be excluded from among the characters of the fully developed 

 animals. The author maintains that dimorphism is here characteristic of 

 the mature adults. (7) Astoma (also Atoma) parasitica, the larva of a 

 species of Tromhidium, is a most striking example of the segmentation of 

 the posterior portion in mites, for both dorsal and ventral surface exhibit 

 four grooves or constrictions. A bibliography is appended. 



£. Crustacea. 



Green Gland of the Crayfish.f — Herr B. Eawitz communicates an 

 account of the histology of the crayfish's green gland, which has been the 

 subject of repeated but yet incomplete investigation. A brief critical 

 account is given of the observations of Leydig, Huxley, Wassiliew, 

 Grobben, and others. 



The gland has " the form of a mallow fruit," and consists of three very 

 difierent substances, the green, the white, and the yellowish-brown. The 

 green substance forms a kind of shell, in which the two others rest. It is 

 thus most developed ventrally, and only a narrow fringe of it is seen on 

 the dorsal surface. The white substance is the largest, it extends over the 

 green, and is alone in connection with the sac. The yellowish-brown 

 substance has a rounded conical form, lies upon and within the white, 

 extending downwards within it to about two-thirds of the entire thickness, 

 and occupying about a fourth of the transverse, and half of the oral-aboral 

 diameter. It is not connected with the green substance. The terms 



■^ Math. u. Naturw. Ber. aus TJngnrn, iv. (1886) pp. 45-61 (1 pi.). 

 t Arch. f. Mikr. Auat., xxix. (1887) pp. 471-94 (2 pis.). 



