8202 



Insects. 



their skin, and Dutrochet found that frogs became noticeably warmer in air saturated 

 with aqueous vapour, and, consequently, suspending their evaporation. — * Intellectual 

 Observer' for September, 1862, p. 146. 



Note on the supposed Discovery of a New British My gale (Zool. 8172). — Mr. 

 Robertson is evidently in error in recording the discovery of Dysdera erythrina, as a 

 species new to Britain. If Mr. R. will refer to Zool. 6501 and 7563 he will see that 

 it is there recorded by myself as " common under stones and rocks at Portland," and 

 " rare on Bloxworth Heath, Dorsetshire." I have, since thus recording it, received a 

 specimen from a London cellar, where it was captured, and kindly sent me by Mr. 

 Edwin Shepherd, of 176, Fleet Street, aud also from Mr. F. Bond, of Kingsbury, 

 where he meets with it occasionally in his greenhouse. Moreover, these records by 

 myself are by no means the earliest of its having been noticed as a British species, for 

 Mr. Blackwall notices it (Linn. Trans, vol. xix. p. 128) as having been found in Man- 

 chester before the year 1835, and in that year at Cambridge. Subsequently also, in 

 the * Annals and Magazine of Natural History,' Mr. Blackwall says he has received 

 it from Oxford, and that " Mr. Walker has met with it on the south coast near the 

 sea-shore." Supposing that Mr. Robertson's spider is Dysdera erythrina, he is again 

 in error in calling it a Mygale ; Walckenaer, in his ' Insectes Apteres,' places it 

 directly following the Mygalkla?, and, in my opinion, rightly so ; Mr. Blackwall, how- 

 ever, conceiving that its normal number of eyes (six, instead of eight as in the Myga- 

 lidae) should have greater weight than Walckenaer gives it, places this species at the 

 head of his second great division of the Araneidea, based exclusively on the number of 

 the eyes, and called " Tribe Senoculina ;" so that in his arrangement the family My- 

 galidae is the first, and that of the Dysderidae nearly the last on the list (see Linn. 

 Trans, vol. xviii. p. 601, where Mr. Blackwall gives his reasons for this, his primary 

 division of the Araneidea). Is Mr. Robertson's species Dysdera erythrina ? — 

 O. Pickard- Cambridge ; Bloxworth, September, 1862. 



Jumping Spiders. — Has it been ascertained by what means the jumping spiders 

 are enabled to regain their hold when springing at a fly on a perpendicular surface ? The 

 direction of the spring must be more or less away from the face of the wall or window 

 pane ; gravitation would draw the creature downwards, and the attraction of matter 

 for matter (which has been suggested) is not found, in practice, to influence light 

 bodies dropped close to the face of a wall. May it be that a thread is attached to the 

 holding-ground at the moment of the spring, which, by tightening, brings the spider 

 back to the surface? — George Guyon. 



New Group of Parasitic Crustacea. — Dr. Fritz Miiller describes parasites of crabs, 

 to which he gives the name of Rhizocephala (root-headed). He says, " The head of 

 these apparent worms, which is inserted in the body of the host, emits roots like those 

 of plants — hollow tubes, which, being much ramified, cling round its intestines, and 

 their brood holds a middle place between that of the Lerneoe and the Cirripedes." 

 The parasite of the Porcellana he calls Lemajodiscus Poreellanae, and that of the 

 hermit crab Sacculina purpurea. Further details will be found in ' Wiegmanu's 



