GONATOPUS SOCIABILIS, N.SP. 7 



taken uhlmanni with L. flavus and L. nigrer in Holland. These large 

 mites are generally found on the underside of the head of the ant. I 

 have found two specimens on one ant. Mr. A. D. Michael has some 

 of my specimens, as also other species, but he has not yet had time to 

 work them out. My best thanks are due to him, as also to Mr. N. D. 

 F. Pearce, for the names of the above. 



Crustacea.— Although Platyarthrus hoffmansegii appears to be our 

 only true ants' nest species, the following records are of interest : — 



Porcellio scaber, Latr. — I took specimens of a fine red variety with 

 Formica sanguinea at Woking. 



Porcellio ratzeburgi, Brandt. — Taken in numbers with Formica 

 rufa at Corbridge, in Northumberland, by Mr. R. S. Bagnall, new to 

 Britain. 



Armadillium opacum, Koch. — I took several specimens of this new 

 species, to Britain, in the heart of a nest of Lasius fuliginosits at 

 Wellington College. I am indebted to Mr. Bagnall for the names of 

 these " wood-lice." 



Explanation of Plate XV (vol. xviii). 



The parts of the ants lettered are as follows : — 



A. Pronotum. B. Mesonotnm. C. Scutellum. D. Post-seutellum. 

 E. Propodeurn. 



Explanation of Plate I (vol. xix). 



Figs. 1-2. — Ripersia donisthorpei, n. sp. x250. 



up. = spinneret, spi. =spine, e. = eye. 

 Fig. 3. — Ripersia formicarii, n. sp. x250. 



Gonatopus sociabilis, n.sp., and a table of the British species. 



By Prof. Dr. T. T. KIEFFER (translated with notes by 

 HORACE DONISTHORPE). 



2 . Black; the first two joints of the antennaa, the head, except above, 

 which is brown-black, the tarsi and the sloping part of the large abdomi- 

 nal segment, of a red-yellow colour; club of anterior femora black-brown, 

 the extremity of the four other femora, and of the four posterior 

 tarsi, a little obscured. Vortex depressed and slightly concave, with a 

 slight median carina. Antenna? reaching the extremity of the thorax ; 

 scape bent, Large, half as long again as the second joint ; second joint 

 twice as long as broad ; third joint slender, equal to the first and 

 second together; fourth gradually thickened; fifth to the tenth equally 

 large, fifth hardly twice as long as broad ; ninth half as long as broad. 

 Thorax bright and smooth ; first node with a transverse impression 

 before the middle, anterior part shorter than the posterior and nearly 

 smooth ; posterior part raised and elongate, narrowing between the 

 two nodes a little shorter than broad; second node elongate, with 

 fairly abundant upstanding hair, having in front, and at the sides, an 

 impression or suture well marked; the sloping part transversely striate. 

 The thin part of the posterior femora longer than the thickened part. 

 Anterior metatarsus equal to the fourth joint, twice as long as tin,' 

 second and third together; the fifth a little longer than the third. 

 Interior joint of the pincers strongly bent before the extremity, which 

 bears 18-15 lamelles (little plates), of which one on one side and 

 three on the other arc; very long; the bent part without plates ; the 

 rest, underneath, bears a row of obtuse plates, touching each other, and 



