204 



SCIENCE-GOSSIP. 



measurement, but the actual outline of the plate 

 varies very much. The one I have figured in this 

 paper is as near as possible to Piersig's figure. 

 Both figs. 2 and 3 have been drawn with the 

 camera under a half-inch objective, so that the 

 difference in size and structure of these two eye- 

 plates can be easily seen. 



This species received the specific name ioari 

 from Dr. Piersig in 1899. 



Localities.' — Dr. George has taken this mite in 

 Lincolnshire, Mr. Taverner in Scotland, and I 

 have found it at Mill Hill and at Lowestoft. 



There is only one more genus to add to those 

 already mentioned in my critical examination of 

 the British freshwater mites, that being the genus 

 T/iyag. This will be described by my esteemed 

 friend, Dr. George, of Kirton-in-Lindsey. This 

 gentleman has written many interesting papers in 

 this Journal on the Arrenuri, and his kind assist- 

 ance has been of great help to me in the produc- 

 tion of these papers. When the genus Thy a* is 

 described I think we shall then have recorded all 

 the known British species up to the time of writing. 

 I have several species not yet identified which 

 may have to be added to the list at a later date, 

 and there must also be a great number yet to 

 record when diligent collectors have found them. 

 for we are yet a long way behind the German list. 

 Still. I think, considering the small number of 

 workers in this country on the Hydrachnidae, we 

 have made a verv eood besinnine. 



called Arrenurus viridis George, unless I decided 

 to give it a new name. On consideration, I think 

 it more satisfactory to rename it. especially as by 

 far the greater number of the specimens I have 

 found are not green, but blue. 



The petiole of this mite, being very ornamental, 

 also a marked and important feature. I have 

 ventured to name the species Arrenurus ornatvs. 

 As many of the present readers of Science-* i SSii 

 may neither have the old volumes of SciENCE- 

 Gossip. nor readv access thereto, and as I have 



Fig. 3. A. ornatuz 

 Male. Petiole. 



Fig. i. A. vrntu -. 

 Hale. Palpus. 



Bryiurgh Road. Putney. London. 

 November 1900. 



w. 



quite recently paid some attention to this mite. I 

 thought I would write another description giving 

 to it the new name, and describing a little more 

 fully this beautiful and interesting creature. I 

 am indebted to Mr. Soar for the accompanying 

 new drawings. 



Arrenurus ornatvs is one of the tailed mites, so 

 called because the males have a peculiar structure 

 posteriorly, and this differs very curiously in the 



AERENURUS ORNATUS »s. 



By C. F. George. M.RC.S. 



~T~S the Old Series of Science-Gossip for Decem- 

 -*- ber 1882, page 273, I figured and described a 

 freshwater mite under the name of Arrenurus 

 viridis Duges. Dr. Piersig has pointed out that 



Fig. 1. A. '.■ ■ 

 Male. Dorsal surface. 



Fi'i. -. A. - 

 Male. Lateral surface. 



A. viridis of Duges is A. maeulator of Miiller. and 

 that the mite figured by me had not previously 

 been described. This mite must therefore be 



N*^ 



Fig. 5. A. ornalus. Male. 

 Petiole of, not full developed. 



Fig. 6. A. oruatut. Male. 

 Dorsal surface of, undeveloped. 



different species. There are two great divisions — 

 one has the tail cylindriforni and more or less 

 narrowed at the base : in the other division the 

 tail is wide, with side corners jutting out, and a 

 petiole projecting freely from the centre of the 

 posterior edge of the tail. Our mite belongs to 

 this second division. The next point is. that there 

 are on the hinder part of the back two elevations 

 like horns, bent so that the points project for- 

 wards. These horns are in A. ornatas distinctly 

 separated from each other at the base. Below 

 these, nearer to the centre of the hind edge of the 

 tail, are two little knobbed elevations, each carry- 

 ing a tactile hair ; under these in the centre is a 

 sharp point over the petiole, and where it joins 

 the tail is a transparent pellicle called the hyaline 



