520 



NATURE 



[March 30, 1905 



The results of the precise levelling operations for the , especially amongst the Lepidoptera and Orthoptera, to 



vear are published in Appendices Nos. 6 and 7, which 

 submit them in a detail that makes them immediately 

 available for the requirements of surveyors and engineers. 

 These extend the precise level net, as previously published, 

 six hundred miles to the westward, from Red Desert, 

 Wyoming, to Owyhee, in eastern Idaho, and from Holland. 

 Texas, two hundred miles south-west, to Seguin, Texas. 

 An interesting feature is an account of the change in thf 

 manner of support for the levelling rods, with the tim- 

 parative discussion of the old and the new methods, and 

 the consequent confirmation of the importance of the new 

 system. 



The account of operations submitted by the assistant in 

 charge gives the story of the work of the various com- 

 puting, drawing, engraving, and chart divisions of the 

 office in which the results of the field work are discussed 

 or prepared for the publications and charts wherein they 

 are placed at the service of the public. 



A full account of the first recording transit micrometer 

 devised for use in the telegraphic longitude determinations 

 of the Coast and Geodetic Survey is submitted in Appendix 

 No. 8, with an account of the exhaustive tests it wa? 

 subjected to, and a recapitulation of the results of experi- 

 ence with this form of instrument, mainly in Europe, 

 during the last thirteen years. The results of these ex- 

 periments indicate that w'ith the transit micrometer the 

 accuracy of telegraphic longitudes may be considerably 

 increased if desirable, or the present standard of accuracy 

 may be maintained at much less cost than formerly. 



The results of all triangulation in California south of 

 the latitude of Menterey Bay are printed in the con- 

 cluding appendix in full, including descriptions of stations 

 as well as their latitudes and longitudes and the lengths 

 and azimuths of the lines joining them. In compact and 

 convenient form there is given all the information in regard 

 to this triangulation that is needed by an engineer or 

 surveyor who wishes to utilise the results in controlling 

 and checking surveys or in constructing maps or charts. 

 The locations of more than 1300 points are accurately 

 fixed by this triangulation. 



The report, in addition to the details of the foregoing 

 operations and results, contains a record of a wide range 

 of important work for which the aid of the Survev was 

 sought because of the special training of its officers. 



PROTECTIVE RESEMBLANCE. 

 A N interesting paper on " Protective Resemblance in the 

 ■^ Insecta," by Sir. Mark L. Sykes, is published in the 

 Proceedings of the Manchester Field Club (vol. i., part ii). 

 After briefly describing the law of natural selection, as. 

 propounded by Darwin, the evolution of new species 

 through variations, and the elimination of the least fit 

 during long periods of time, reference is made to the 

 colours of insects, to the advantage of conspicuous adorn- 

 ment, and the consequent easy identification of those of 

 them which possess some feature repellent to the insect- 

 eating animals. The absence in young animals of an in- 

 tuitive faculty of discrimination between edible and in- 

 edible material in the selection of food is emphasised, and 

 reference is made to authors who have experimented on the 

 subject. 



Miiller's theory of mutual protection, through similarity 

 of colours and patterns, amongst inedible Lepidoptera, and 

 Bates's explanation of the " mimicry " or simulation of 

 distasteful species by edible species, are described, and the 

 superficial resemblances between entirely different species 

 and genera are attributed to the influence of natural 

 selection and elimination, and the transmission and accumu- 

 lation of variations. The method by which many of these 

 likenesses are produced is shown by a number of camera 

 lucida drawings of the wing scales of many of the butter- 

 flies and moths referred to and illustrated in the article ; 

 and the scale variations, in colour, size, pattern and ar- 

 rangement, which produce a common resemblance in the 

 insects, are described. Another branch of the subject, 

 treated in some detail, is protective resemblance of environ- 

 ment, as seen in the striking similarity of many insects, 



NO. 1848, VOL. 71] 



leaves, twigs, moss, &c. ; and a number of illustrations are 

 given of resemblance to natural surroundings, three of 

 which we select as examples. 



Fig. I. — Em6usa gortgylcdis (Ceylon) at rest on iwi 



.^mong the many curious and interesting insects which 

 are found in Ceylon, Enipnsa gongylodes is one of the most 

 singular. It is a brown insect. The thorax is like a long 



Fic. 2.—Eurjirachis Westlivi'iiii (Ceylon) with th^ wines expanded, and 

 at rest upon a piece of bark. 



thin twig, with a wide leaf-like expansion immediately 

 behind the head. The wings are broad, veined and 

 cruiTipled, like dried leaves, and the long legs, which are 

 spread out in any direction as the animal is at rest, har- 



