412 SUMMARY OF CURRENT RESEARCHES RELATING TO 



guishcs two types of hair, one in which tho cuticular root-portion is 

 thick compared with the free stem, a second in which the root is tho 

 more delicate portion. The first or tactile hairs are described at 

 length and contrasted with the second or protective hairs. As to those 

 hairs which Dahl described as auditory, two types occur, and minor 

 variations besides. They are not uniform structures. A very distinct 

 third type, swollen in a cucumber-like expansion, was observed by the 

 author on a species of Mygale brought from New Guinea by Korotneff. 

 The three forms are very carefully described, but the details can hardly 

 be compressed. It is more important to notice Herr Wagner's con- 

 clusions : — (1) That the functions of the types described cannot be 

 supposed to be identical ; (2) that no one of the types can be recognized 

 as auditory. 



What, then, is their function? They are more perfect and 

 more sensitive than the ordinary tactile hairs. They can be affected 

 by slight agitations which do not influence the latter. Herr Wagner 

 is convinced that their role is to perceive finer sensations, such as 

 those which indicate the approach of rain. Thus it is intelligible why 

 the vagabond forms should have these hairs in much richer abundance 

 than the sedentary forms, in which (e.g. in EpeiridaB and Theridiidse) 

 they occur only on the tibia and the metatarsus. 



New Orb-weaving Spider.* — Dr. H. C. M'Cook has discovered in 

 Florida a new orb-weaving spider, which he calls Cyrtopliora bifurca. 

 Though with some resemblances to C. caudata of Hentz, it differs entirely 

 in the shape of its cocoon, for this is of a somewhat irregular octagon 

 shape, and is of a light-green colour. The number of cocoons found on 

 one string varied from ten to fourteen ; they are bound together by con- 

 tinuous series of thick white threads, which extend from the top to the 

 bottom of the string. Within each cocoon, which consists of two parts, 

 there is a very slight tuft of flossy white silk, in which the eggs are 

 deposited. The spider is of about the shade of its cocoon ; the female 

 is most remarkable for the cleft at the apex of the conical prolongation 

 of the abdomen. 



British Oribatidae-t — Mr. A. D. Michael has published the second 

 volume of his admirable monograph of the British Oribatidae. An 

 amended table is given of the genus Tegeocranus and the genera Notaspis 

 (with nineteen species), Damseus (with eight), Hermannia (with six), 

 Eremseus (with two), Nothrus (with thirteen), Hypocthonius (with four), 

 and Hoplophora (with five), are described in detail. An amended table, 

 with descriptions of two new species, is also given of Scutovertex. A few 

 nymphs whose adults were included in the first volume are described, 

 and supplementary notes are made on other species. 



The author considers the classifications recently proposed by 

 Canestrini and by Berlese, and makes some emendations of his own 

 earlier classification, the most important of which is the reduction of 

 the monodactyle and tridactyle distinction to specific instead of generic 

 value, in consequence of the discovery of some monodactyle species of 

 Nothrus. It will be remembered that Mr. Michael made use of this 

 means of distinction with some reluctance. 



* Proc. Acad. Nat. Sci. Philad., 1887, pp. 342-3. 



t British Oribatidce, ii. (Kay Society's vol. for 1887), London, 1888, pp. i.-xi. 

 and 337-657, pis. xxv.-liv. 



