506 



SCIENCE 



[N. S. Vol. XXIX. No. 743 



family Cassididse.* Many larvae of these 

 beetles have peculiar lateral expansions of the 

 body, and a long spiny or bristly tail, which 

 accumulates excrement and cast-skins, and is 

 recurved over the body. When disturbed the 

 lai-vse erect and wave these tails. He con- 

 cludes that these structures are used princi- 

 pally as a protection against parasitic enemies. 

 The eggs are enclosed in a case, frequently 

 one in each case, and these cases are often 

 covered with excrement. 



Mr. H. S. Smith has published a most use- 

 ful work on the Hymenoptera of Nebraska," 

 a synoptic and descriptive catalogue of the 

 Sphegoidea of that state. There are tables to 

 the genera and species, and descriptions of 

 fifteen new forms; altogether over 200 species 

 are recorded from the state. It is hoped that 

 some eastern hymenopterists will follow the 

 example. 



Professor E. B. Poulton has published a 

 detailed museum study of our butterflies of 

 the genus Limenitis" tending to show the in- 

 fluence of Anosia plexippiis and Danaida 

 herenice upon L. archippus, and its varieties. 

 He also considers that L. calif ornica is the 

 model of L. lorquini. Although he brings out 

 many interesting points about coloration and 

 pattern, one can not fail to notice the paucity 

 of field observations which alone are of de- 

 termining importance in these matters. The 

 author considers that Papilio pTiilenor is 

 mimicked by three other species of the genus 

 — P. iroiluSj P. asteriiis (female) and P. 

 glaucus (female), which would hardly be sus- 

 pected by any one familiar with these butter- 

 flies in the field. 



Mr. W. Lundbeck has published the second 

 part of his book on Danish diptera.' As with 



* " Life Histories of some Philippine Cassididse," 

 Phil. Journ. Soi., III., pp. 261-271, 6 pis. 1908. 



" " The Sphegoidea of Nebraska," Vniv. Studies, 

 Vol. VIII., No. 4, October, 1908, pp. 88, I plate. 



" " Mimetic North American Species of the 

 Gfenus Limenitis and their Models," Trans. Ent. 

 Soc. Land., 1908, pp. 447-488, 1 plate. 



' " Diptera Danica ; Genera and Species of Flies 

 Hitherto Found in Denmark." Part II., Asilidae, 

 Bombylidse, Therevidse, Scenopinidse. Copenhagen, 

 1908, pp. 1G2, 48 figs. 



the preceding part, this is a most excellent 

 treatment of the subject. The structural 

 characters are given in great detail; there is 

 a good account of habits and life-history; 

 and under the Asilidae are numerous records 

 of their prey, showing that there is no mim- 

 icry of their prey by these ferocious flies. Al- 

 though the species known from Denmark are 

 very few, the author's treatment of the genera 

 and families is so full as to make the work a 

 most useful one to the American dipterist. 



Attention should also be called to the 

 recent catalogue of Argentine Diptera by Dr. 

 J. Brethes.' He lists the flies of Argentina, 

 Patagonia, Uruguay and Paraguay, 650^^ 

 species in all; mostly in the Asilidae and Syr- 

 phidse. There are 23 species of mosquitoes. 



Nathan Banks 



SPECIAL ARTICLES 



CONCERNING THE EXISTENCE OF NON-NITEIFYING 



SOILS 



It is believed by agricultural specialists as 

 well as by bacteriologists that soils generally 

 have the power to convert organic or am- 

 moniacal nitrogen into nitrate nitrogen, i. e., 

 to nitrify. Nitrifying organisms are sup- 

 posed to abound to such an extent that any 

 stratum not possessing them would soon be- 

 come inoculated with them by air, soil^ 

 manure, water or other means.' 



Filter beds, originally non-nitrifying, soon 

 become vigorous nitrifiers without inoculation ; 

 sewage nitrifies freely in running streams; 

 nitrate as saltpeter is of almost universal 

 natural occurrence. A surface soil which can 

 not nitrify would be regarded as a rare 

 anomaly, therefore, and that many such non- 

 nitrifying soils exist, could not be expected 

 from the generally assumed conditions. 



During our work of the past few years, we 

 have, however, been repeatedly confronted with 

 the fact that many of our soils do not nitrify. 

 The first evidence of the existence of non- 



' " Catalogo de los Dipteros de las Republicas 

 del Plata," Anales Mus. Nao. Buenos Aires (3), 

 IX., pp. 277-305, 1908. 



^ Le Far, " Handbuch der Technischen Mykol- 

 ogie," III., 147. 



