HARVARD UNIVERSITY ao = LIBRARY OF THE Museum of Comparative Zoology aa vi Qe ee Aaa Py ah a ys a NG yh i 1) j fi thy tM ‘ wi) Poy THE few eo OG 1h bee INSTITUTED MDCCCXLIV. This volume is issued to the Subscribers to the Ray Society for the Year 1871. LONDON: MDCCCLXXITE. IM ONO Gal A.P Eb ie OF THE COLLEMBOLA AND THYSANURA. BY Sm JOHN LUBBOCK, Bazt., M.P., VICE-PRESIDENT OF THE ROYAL SOCIETY; VICE-PRESIDENT OF THE PRITISH ASSOCIATION; VICE-CHANCELLOR OF THE UNIVERSITY OF LONDON; FELLOW OF THE LINNEAN, GEOLOGICAL, AND OTHER LEARNED SOCIETIES, ii, OND OUN:: PRINTED FOR THE RAY SOCIETY. MDCOCLXXITI. PRINTED BY J, E. ADLARD, BARTHOLOMEW CLOSE. PREFACH. Tue animals which form the subject of this work were first grouped together by Latreille under the name of THysanura: to me, on the contrary, they appear to form two distinct orders, for one of which I have proposed the term Cortnempota. They have hitherto been much neglected by English naturalists. And they from their small size, and the delicacy of their structure, which renders them uninteresting to col- lectors, together with the absence of well-marked meta- morphoses, this is, perhaps, not surprising; yet the two groups are in many respects of singular interest. It is unfortunate that the two naturalists, M. Nicolet and M. Abbé Bourlet, who have of late years contributed most to our knowledge of the CoLtt=mpona, should have published the results of their labours almost simultaneously; and as they worked quite independently of one another, the consequence has been to complicate greatly those difficulties of nomen- clature which, owing to the brevity of early descrip- tions, were already sufficiently embarrassing. Several, for instance, of Linnzeus’ specific characters would apply to more than one species, and even to more than one genus. I have reason, therefore, to be vi PREFACE. very grateful to M. Tullberg, who has been so good as to send me several Swedish species, and has thus enabled me to form in these cases a more decided opinion than could otherwise have been possible. I must also express my thanks to Mr. McIntire for much assist- ance in the collection of English species, as well as for many valuable suggestions. The scales of the THysanura and CoLLemBona have long been a subject of much interest to microscopists. Through the kindness of Mr. J. Beck I am able to give some beautiful plates of scales drawn by his brother, the late Mr. R. Beck. Mr. J. Beck has added a detailed description of these plates, as well as some interesting remarks on the subject, which will be found in an Appendix. I regret that I did not receive these descriptions in time to introduce them under the heads of the several species. In the present work I have confined myself to the existing species, as | have not had the opportunity of studying any extinct representatives either of the CottEMBoLA or TuysaNura. If, however, the views ‘advocated in the third chapter are correct, both types must have had their origin far back in geological time. From the fragility of their structure we can hardly hope that the extinct forms will ever be well known tous. Yet the prospect is not so hopeless as it might at first sight appear. A certain number of fossil species have already been discovered. Koch and Berendt, for instance, in their work ‘‘ Die in Bernstein befindlichen Crus. Myr. Arach. und Apteren der Vorwelt,” published at Berlin in the year 1854, describe species of Smynthurus, Isotoma, Degeeria, Lepisma, and Machilis, and also a form, characterised PREFACE. Vil by swollen antennz, for which they have proposed the name Paidiwm. They likewise refer to the 'THysanuRA two doubtful species, for which they have proposed two new genera, Acreagus and Gilessaria. The latter has been regarded by some as a neuropterous, by others as a coleopterous, larva; while Acreagus has been referred by some to the Heniptera, a view in which I am disposed to concur. Whatever shortcomings may be found in this work, and while no one can be more sensible of them than myself, I believe that the plates must meet with general approval. Of the anatomical drawings, indeed, which were mostly made by myself with the aid of the camera lucida, [ will say no more than that I believe they will be found to be correct; but the representations of the species, and the general execution of the plates, are the work of Mr. Hollick, a gentleman who is unfor- tunately deaf and dumb, but in whom these terrible disadvantages have been overcome by natural genius. I believe this is the first work which has ever been illustrated by a deaf and dumb artist. It will be seen that Mr. Hollick has spared himself no labour or pains. I feel much indebted to him for the conscientiousness with which he has reproduced the minute details of the originals, as well as for the beauty and accuracy of his work. HiegH Eitms, Down, KENT; 13th March, 1872. TABLE OF CONTENTS. PAGE INTRODUCTION. ‘ : : ; ‘ i REVIEW OF PREVIOUS LITERATURE ON THE GROUP . : 3 CHAPTER I. On the classification of the CoLLEMBOLA and THYSANURA w oll CHAPTER II. On the importance of the COLLEMBOLA and THYSANURA in rela- tion to the evolution of the Insecta ; . . AO Relation of the larva to the imago . : : . 42 Developmental and adaptive changes : . 44 The genus Campodea ; ; : : . 45 Different classes of larve . : : ; AD Importance of the mouth-parts , : : . 48 Possibility of changes in the mouth-parts . ‘ 2 oll Nature and origin of the wings ‘ : : . od CHAPTER III. CoLLEMBOLA—general description. : : Lee SO The head : : ‘ : : . 56 The thorax and the abdomen : : : «6% Specific differences : : : : ee Habits. ‘ : : : : Pat Internal anatomy . : ; ; ; ade Embryology ; : : : : . 84 Nervous and muscular systems . : : = 89 Smynthurus . Papirius Orchesella Tomocerus Tritomurus . Templetonia Seira Achorutes Podura . Lipura . Anoura General organization . Campodea lapyx Lepisma Lepismina APPENDIX.—Kssay on the Seales of the Collembola and Thysanura. By Joseph Beck TABLE OF CONTENTS. COLLEMBOLA. Smynthuride. PAGE 100 | Dicyrtoma Papiride. 120 | Degeeriade, 129 | Beckia . 136 Lepidocyrtus 140 Degeeria 142 Isotoma 143 | Poduride. 177 | Xenylla 185 Tipuride. 188 | Anouridea. 197 | THYSANURA. 201 | Internal anatomy . Campodeade 212 | Nicoletia Lapygide 215 | Lepismide. 217 | Machilis 230 PAGE 117 148 150 158 167 187 235 249 INTRODUCTION. Tar CoLLeEMBoLA and Trysanura, which form the sub- ject of the present work, have hitherto been but little studied in this country. Yet if a fallen bough be ex- amined, a heap of moss shaken over a pocket-handker- chief, or any long herbage swept with a hand-net, the naturalist will not fail to find, together with numerous beetles, flies, and other insects, certain delicate, hexa- pod, active little creatures ; the majority of which will endeavour to escape not only running with agility, but also springing with considerable force, by means of a sub-abdominal, forked organ, which, commencing near the posterior end of the body, reaches forward, in most cases, almost as far as the thorax. These constitute the Linnean genus Podura, or Springtail ; subsequently combined by Latreille with Lepisma, and elevated to the rank of an order under the name T'HYSANURA ; but which, for reasons to be given presently, I have again proposed to separate from the Lepismide, and to call Cotnempona, leaving Latreille’s name THysANuRA for the other portion of his group. Both the Tuysanura and the Connemsona frequent dark places; but while the former prefer dry walls, heaps of stones, or warm rooms—in short, warm and dry places—the latter, with few exceptions, can only live in moist situations, and suffer little from cold. Owing to their very general intolerance of heht, we know little as yet with reference to the habits of the 1 2 INTRODUCTION. eroup, though some particulars will be found under the head of the different species. As a general rule, they seem to take little notice of one another; but in the case of Smynthurus luteus, a very common Species in our meadows, the males are very attentive to the females, and caress them lovingly with their antenne. Some species, as, for instance, Smynthurus aquaticus and Poduwra aquatica, live on the surface of ponds; some are found on the sea-shore ; others, as Seira domes- tica, in houses; but the majority of species frequent fungi, decaying leaves, moss, or loose soil: in fact, wherever there is any decaying vegetable matter, - COLLEMBOLA may be found in abundance. Several species of Sinynthurus and Papurius curiously resemble certain small spiders. Thus, the markings ‘and colour of P. ornatus are very like those of certain species of Theridion and Hpewra; while S. fuscus so closely resembles certain small brown spiders that I have myself, when collecting, been more than once deceived. We have here, therefore, I think, a case of that ‘“‘mimicry”’ which has been so well described by Mr. Bates and Mr. Wallace, and I cannot doubt that this similarity to spiders tends to protect Smynthwrus and Papirius from attack. The eggs are laid either singly or in groups, but I know of no species which makes any kind of nest. The young, when first hatched, have the six legs well developed, and present a general resemblance to their parents, differing, however, in proportions, colouring, and, in some genera, in the form of the antennex. We know little as yet with reference to the geogra- phical distribution of the group. It would appear that the same species occur throughout Europe, or, at least, in Sweden, Switzerland, France, and Hngland, where they have been most carefully studied, while some few of them are said to extend to Greenland. As regards other parts of the world, the few species recorded have generally been regarded as distinct, but our infor- INTRODUCTION. mation with reference to extra European species is as yet very meagre. The synonymy of the group is unfortunately much involved. This has arisen partly from the fact that the descriptions given by the earlier writers, excepting always De Geer, are so short that it is in many cases impossible to determine satisfactorily the species, or even the genus; partly from the fact that some species vary very “much in colour, and partly from the accident that Bourlet and Nicolet, who have described a consi- derable number of species, published the results of their labours almost simultaneously, and without being aware of one another’s writings. Under these circumstances I have thought it desirable to give lists of the names used by some of the principal writers on the group, together with those by which I think the species should ‘be known. In some cases, however, the species are unfortunately quite undeterminable from the characters given, and others, probably, are mere varieties of one another. The first memoir on the group to which I think it necessary to refer was published by De Geert under the title ‘‘ Experimenta et Observationes de parvulis insectis, agili saltu corpuscula sua in altum levantibus, quibus Podure nomen est, exhibite.’”’ He describes in detail, and with his usual accuracy, four species, viz. Podura campestris nigra, our Isotoma arborea ; Podura campestris cinerea == Degeeria nigromaculata ; Podura aquatica mgra, still known as P. aquatica ; and Poduwra aquatica cinerea, which is our L[sotoma stagnorum. The memoir is illustrated by four plates. Three years later De Geer published a second memoir,” in which he described and figured the first species of Smynthurus, S. fuscus. He recognised its affinities to the Poduride, and described it as follows :—** Podura fusca, globosa, nitida, antennis longis, articulis pluri- mis,” 1 « Acta Soc. Reg. Sci. Upsaliensis,’ 1740, p. 48. 2 *Kongl. Swenska Wet. Acad. Hand.,’ 1743, p. 296. 4. INTRODUCTION. Linneeus, in the first edition of the ‘ Fauna Suecica,’ described nine species of Podwra, namely, P. viridis, atra, globosa fusca, teres plumbea, nivalis, arborea nigra, aquatica gra, viatica, and terrestris alba. P. viridis seems undoubtedly to be our Sinynthurus viridis. P. atra is more doubtful; his description is, * P. atra, abdomine subgloboso, antennis longitudine corporis ; apice albis.” In the ‘Systema Nature,’ on the contrary, these characters are given under the name of P. polypoda, and P. atra is made synonymous with De Geer’s P. fusca. On the whole, I am disposed to regard the P. atra of the ‘ Faun. Suec.’ (P. polypoda of the ‘ Sys. Nat.’), as our Papirius polypodus. This species occurs in Sweden, whence M. Tullberg has been so kind as to send me some specimens. It has white tips to the antennz; but, on the other hand, in this country it is rather violet than black. P. globosa fusca nitida is, in all probability, our Smynthurus fuscus. P. teres plumbea has been generally regarded as the species which must, I think, now bear the name of Tomocerus plumbeus. It has been so consi- dered by most of those who have written on the group, but the determination seems to me very doubtful. P. nivalis is still known by the same name. P. arborea mgrais probably the Isotoma arborea of subsequent writers. P. aquatica is also still known under that name. It is impossible satisfactorily to identify the species described under the name of I. via- tica, but most writers have denoted a small black species of Jsotoma by that name, and they are probably correct. Lastly, the P. terrestris alba has given rise to great confusion. In the second edition of the ‘ Fauna Suecica,’ and in the ‘Systema Nature,’ this species is described as P. fimetaria. It is clear, however, that the P. fimetaria of the ‘Faun. Suec.’ is not the P. jimetaria of the ‘ Sys. Nat.’ Of the former, Linneus says that “ infinita copia occurrit, et atomorum volitantium instar saltat,”’ and he describes it as “ omnium minima, totaque alba.” INTRODUCTION. +5) It was, probably, a young Isotoma. On the contrary, the P. fimetaria of the ‘Sys. Nat.’ is described simply as P. terrestris alba; but he adds “non salit.” It is probable, therefore, that the P. Jimetare va of the * Sys. Nat.,’ though not that of the ‘Faun. Suec.,’ is the Species now “known as LIipura fimetaria. The following is a list of the species with the names used in the present work: Linn vs, ‘ Fauna Suecica,’ 1746. Tinn. Mihi. Podura viridis = Smynthurus viridis. 5 abre Papirius polypodus ? - elobosa fusca nitida fey » teres plumbea Tomocerus plumbeus ? » nivalis a3 nivalis. » arborea nigra Isotoma arborea. » aquatica nigra Podura aquatica. i ©6O Wdaibica » viatica P » terrestris alba Young Isotoma. In the second edition of the ‘ Fauna Suecica,’ pub- lished in 1761, Linnzus omits the P. viatica, with reference to which even in the first he had expressed a doubt whether it was not identical with P. aquatica. On the other hand, he adds two new species, P. cincta, which is evidently Orchesella cincta; and P. ambulans, which is described as ‘* P.ambulans alba, furca extensa;”’ while the somewhat longer description given in the ‘Syst. Nat.’ is, “ P. alba, cauda bifida extensa obtusa. Corpus cylindricum, reliquis longius, album, molle. Punctum fuscum supra anum. Cauda setis 2 exten- sis, longitudine $ corporis. Non salit.”” This species seems, from the above description, to have been a Campodea. On the other hand, De Geer’s P. ambulans does not answer to either of the above descriptions, but appears to be our Lipura ambulans. It does not seem to have been noticed by any writer that Lipura ambulans is mentioned in the first edition of the ‘ Faun. Suec., though not among the Podure, bemg described as a Pediculus, although Linneeus adds ‘ facies omnino Podure.” 6 INTRODUCTION. Geoffroy,' in 1762, placed Podura and Forbicina (Lepisma) between Pediculus (the Louse) and Pulex (the Flea). He divided the Podure into—I1st, Globulose; and 2nd, Longe. Of the first group he described three species under the names P. atra, P. viridis, and P. polypoda. His P. viridis is evidently the Simynthurus viridis of subsequent authors, but P. atra and polypoda are more difficult to identify. I have sometimes been disposed to think that they were both founded on the common brown Smynthurus, but it 1s possible that P. polypoda may be my Papirius fuscus. Of the “* Podures allongées” Geoffroy describes seven species, namely, P. villosa, which is evidently an Orchesella, and probably O. villosa; P. livido-lutea, which is probably Degeeria nivalis, or perhaps, as Geoffroy himself suggests, a young specimen of P. villosa; P. annulata, which appears to be Orchesella cincta; P. viatica; P. aqua- tica; P. plumbea; and P. violacea, which may be a Lepidocyrtus, or, as Geoffroy himself suggests, a young specimen of P. plumbea. Lepidocyrtus is, however, so common that I incline to the first hypothesis. Of Forbicina Geoffroy described two species, F. plana, and F’. cylindrica. He characterised the genus Podwra as follows :— “Pedes sex. Oculi duo. Antenne filiformes. Ab- dominis cauda bifurca inflexa saltatrix. Corpus squa- mis tectum.” The first three characters are common to many other groups, and the last two are not general in this. Of Forbicina he gave the following description :— ‘“* Pedes sex, origine lata et squamosa. QOculiduo. Os tentaculis duobus mobilibus. Antenne filiformes. Abdominis cauda tripilis. Corpus squamis tectum.” The following is a list of Geoffroy’s species : Podura fusconigra = Smynthurus fuscus. » viridis a viridis. 1 « Histoire des Insectes qui se trouvent aux environs de Paris,’ INTRODUCTION. 7 Podura fusca = Papirius fuscus. » villosa Orchesella villosa. » livido-lutea Degeeria nivalis, or an =) era Orchesella cincta. Sevaatica, Isotoma, viatica. » aquatica Podura aquatica. » plumbea Tomocerus plumbeus. » violacea 3 » P Linneus, in the twelfth edition of the ‘Systema Nature’ (1767), placed Lepisma and Podura at the head of the Aptera, followed by Termes and Pediculus. Lepisma he characterised as follows :—‘‘ Pedes VI cursorii. Os palpis 2 setaceis et 2 capitatis. Cauda setosa: setis extensis. Corpus squamis imbricatum.” Of Podura he gave the following description :— “Pedes VI cursorii. Oculi 2 compositi ex octonis. Cauda bifurca, saltatrix, inflexa. Antenne setaceze elongate.” Of Lepisma he described three species, LD. saccharina, L. polypoda, and L. terrestris. Of Podwra he was acquainted with fourteen, namely, P. viridis, polypoda, atra, plumbea, minuta, nivalis, vaga, arborea, villosa, cincta, pusilla, aquatica, fimetaria, and ambulans. Linnavs, ‘Sys. Nature,’ ed. xu. Podura viridis = Smyntburus viridis. 5 polypoda op atra 5, plumbea muna x nivalis » vaga > arborea 5, villosa ee eimeta, » pusilla » aquatica >» fimetaria » ambulans Papizius polypodus. Smynthurus fuscus. Tomocerus plumbeus. ? Degeeria nivalis ? Orchesella cincta. Isotoma arborea. Orchesella villosa. s cincta. Lepidocyrtus pusillus. Podura aquatica. Lipura fimetaria. Campodea staphylinus ? Fabricius, in his ‘Systema Entomologiz,” places Lepisma and Podura among his Synistata, between Oniscus and Ephemera. He describes five species of Lepisma, and sixteen of Podura, the latter bemg the 1 «Systema Entomologiez,’ 1775, 8 INTRODUCTION. same as those of Linneus, with the addition of P. annulata and P. lignorwm. Miiller, in 1776,’ described four species of Lepisma and seven of Poduwra. His descriptions are very short, and, though characteristic as far as they go, sometimes leave even the genus doubtful. In several cases I can- not even guess at the species which is intended. Some of his descriptions appear to have been taken from injured specimens. ‘Thus, Lepisma terrestris 1s de- scribed simply as ‘‘ nuda, cauda triplici.” But unfortu- nately, all the Lepismide have scales and three caudal appendages. The first portion of the description, therefore, applies to no Lepisma; the rest to them all. Possibly he may have had a Nicoletia before him, but that genus has not yet been recognised in Denmark. Again, Podura motitans, P. nemoralis, P. argenteo- aurata, and P. cerulea are so shortly and insufficiently described that I cannot even guess to what genus they belong. Miller. Mihi. Lepisma saccharina = Lepisma saccharina. Ms terrestris — i polypoda Machilis polypoda. 5 minuta Lepismina minuta. Podura viridis Isotoma viridis. xy ER Smynthurus fuscus. .» plumbea Tomocerus plumbeus. a mivalis Degeeria nivalis. » aquatica Podura aquatica. AF arborea Isotoma arborea. , fimetaria Lipura fimetaria. » ambulans Campodea P » motitans P » sylvatica Orchesella villosa. - nemoralis — » aquatilis Tsotoma aquatilis. » crystallina Templetonia crystallina. » longicornis Tomocerus longicornis. » palustris Isotoma palustris. » argenteo-aurata 3 cerulea 1 * Zoologie Daniz Prodromus, seu animalium Danie et Norvegize indigenarum characteres, nomina, et synonima imprimis popularium.’ Hafniz, 1776. INTRODUCTION. 9 Schrank,’ in 1781, recorded the following nine species, viz. Podura alba, viridis, nivalis, arborea, plumbea, villosa, aquatica, fimetaria, and monura. He places them all under the genus Podura, and his descriptions of the first eight are word for word the same as those of Linnzeus. P. monura is described as occurring with and much resembling O. fimetaria. It is, however, rarer, greyer, and slightly smaller; the antenne are four-jointed, the eyes black; the insect is covered with hairs, those on the body being the longest. The chief peculiarity, how- ever, lies in the tail, which is three-jointed, but not double. Moreover, the third segment is described as retractile within the second. The animal jumps, but not very actively. Subsequent writers do not appear to have met with any species answering to this de- scription. I am disposed to think that Schrank must have had before him a specimen with an accidentally mutilated tail. De Geer, in the seventh vol. of the edition of his great work published in 1782,’ treats of Lepisma and Podura between the flea and the white ant. Of Lepisma, or, as he calls the genus, Forbicina, he mentions only one species, the common JL. saccharina. Podura he divides, like Geoffroy, into two families, one containing Podwra and the other long species, the second corresponding to the Siynthuride. Of the Poduride he describes P. arborea, nivalis, aquatica, aquatica grisea, plumbea, and ambulans. Of the Snvynthuride he only knew the S. ater, which, how- ever, he describes with his usual accuracy. Of these the P. aquatica grisea is the only one not in the ‘Systema Nature.’ As already mentioned, however, his P. ambulans is not the P. ambulans of Linneeus. De Geer’s figures enable us to determine several of Linnzeus’s species which it would be otherwise impos- 1 «Enumeratio insectorum Austrie indigenorum.’ * «Geschichte der Insecten,’ vol. vii, p. 8. 10 INTRODUCTION. sible to fix satisfactorily, as the descriptions given by Linnzeus are quite insufficient for the purpose. De Geer, ‘ Gesch. Ins.,’ vol. vi. Podura arborea nigra = Isotoma arborea. Fe » grisea Degeeria annulata. » aquatica nigra Podura aquatica. A . grisea Isotoma stagnorum. » plumbea Tomocerus plumbeus. » ambulans Lipura ambulans. » globosa fusca Smynthurus fuscus. In 1783 O. Fabricius published’ a memoir on the group, in which he describes seven species—P. hum- cola, P. hypnorum, P. cincta, P. gigas, P. longicornis, P. crystallina, and P. minuta, the latter being, I think, Papirius wigromaculatus. Fabricius, in 17938,” places the genus Podura (with Lepisma) at the head of the Syyistara, and immediately before Ephemera, following Gryllus, with which he closes the Ulonata. He records seventeen species, which are the same as the first sixteen in Gmelin’s ed. of the ‘Sys. Nat.’ (with the addition of P. signata), and are described in the same words; adding, how- ever, the P. annulata and P. lignorum, which he describes as “‘ plumbea capite thorace pedibus furcaque pallidis.” This species, I think, it is impossible to identify with any certainty. He describes the mouth of Podura as containing four subclavate palpi, which is certainly not the case. Of Lepisma he describes five species, L. saccharina, polypoda, lineata, villosa, and collaris, the two latter being respectively inhabitants of China and the American islands. In the year 1796 Latreille mstituted the order THysaNurA, Which he united with the ‘ Parasrv,” and placed after the Mites, at the end of the Aptero- dicera, commencing the winged groups with the Coleoptera. 1 «Kong. Danske Vid. Sels. Skr.,’ 1783. 2 « Entomologia Systematica.’ INTRODUCTION. i | He characterises the Tuysanura as possessing * Os mandibulis, palpis, labro et labio, corpus seepius squa- mosum aut hirsutum, errans, ano setoso caudave furcata. Insecta cursu veloci, vel saltatorii.” He divides the THysanura into two families 2! Ordo Primus. Thysanoura. Thysanoures. Palpi exserti, elongati: anten-) Familia prima. ne a basi ad apicem multiarticu- — late, articulis innumeris, brevissi- Lepismene. mis; cauda setis tribus exsertis. Lépisménes. A R : : : oye TEYSANOURA Palpi nec exserti, nec facile con- |) Familia secunda. spicui: antenne articulis paucis, | — aut apice tantum multiarticulate ; Podurelle. ; cauda furcata, sub abdomine in- Podurelles. flexa. Subsequently in 1810" heplaced the Tuysanura between the Myriapopa and Parasita, as the third order of the Aracunipa. He distinguished two genera of Lepismide, Lepisma and Machilis, and two of Poduride, separating the globular species under the name of Simynthurus, which has since been generally adopted. Lamarck, in his ‘ Animaux sans Vertébres,’ adopts the group Taysanura, of which, however, he only mentions six species, namely, Simynthurus fuscus, S. viridis, and S. signatus, Podura aquatica, P. villosa, and P. plumbea. The ‘Journal of the Academy of Philadelphia’ for 1820+ contains a short paper by Mr. Say on the Trysanura of the United States. Besides a species of Machilis, he describes three species of Podwra and one of Smynthurus. He gives, unfortunately, so few par- ticulars that it will probably not be very easy for American naturalists to identify them, nor is it, I think, possible even to conjecture how far they are distinct from our European species. His P. wricolor is 1 «Genera Crustaceorum et Insectorum.’ 2 « Considérations générales sur Vordre naturel des Crustacés, des Arachnides et des Insectes.’ 12 INTRODUCTION. probably a Lepidocyrtus ; P. fasciata, a Degeeria; and P. bicolor, perhaps, an Isotoma. In 1831 M. Dufour described,! in the ‘ Ann. des Sci. Nat.,’ two new species of Lepisiude. Latreille’s memoir on the “ Organisation extérieure et comparée des Insectes de l’ordre des T'hysanoures,” nm the ‘ Nouvelles Annales du Muséum @histoire naturelle,’ 1832, is principally occupied with a description of the external anatomy of the Lepismide. As regards the Poduride, he very justly questions the accuracy of the description of their manducatory organs given by Fabri- cius, which, indeed, he does not hesitate to characterise as ‘‘absolument fictive.” He is, however, himself in error when he considers the gastric tube as the ex- ternal generative organ. Boisduval and Lacordaire, in their ‘ Faun. Ent. des Eny.de Paris,” adopted Latreille’s group of Thysanoures, and repeat the specific descriptions given by previous writers. The first volume of the ‘ Transactions of the Ento- mological Society of London’ contains a very valuable memoir’ on Irish Tuysanura by Mr. Templeton. This paper is accompanied by two excellent plates. He founded two new genera, Orchesella and Achorutes, both of which have been adopted by succeeding writers. Orchesella : Antenne 6- or 7-jointed, nearly as long as the body, filiform; fork developed. And Achorutes : Antenne 4-jointed, shorter than the head; fork obsolete. He described briefly the following species : Orchesella filicornis = Orchesella cincta. 9 cincta ” 9 1 «Ann. des Sci. Nat.,’ 1831, p. 419. * «Faun. Ent. des Env, de Paris,’ 1835, # «Trans. Ent, Soc. London,’ 1834, p. 92. INTRODUCTION. 115; Podura plumbea = Tomocerus plumbeus. » nitida Templetonia crystallina. » migromaculata Degeeria annulata. » albocincta i albocincta ? » cingula Orchesella cincta. » fuliginosa Isotoma arborea. stagnor um . palustris. Achor utes dubius Achorutes dubius. . muscorum Anoura muscorum. Smynthurus viridis Papirius Saundersu. 5 atra Smynthurus fuscus. ss signata Papirius nigromaculatus. His P. cingula is, I think, founded on a young speci- men of O. cincta. His WN. viridis is not the species so named by Fabricius and other authors, but Papirius ornatus. So also his 8. signata is not the 8. signatau of old authors, but my Papirius nigromaculatus. Mr. Westwood has prefaced Mr. T'empleton’s paper by some valuable introductory remarks. He points out the interesting character of the group, both from its structural peculiarities and also “ from the rank which they hold amongst annulose beings, being one of those questiones vewate which it is most desirable should be set at rest.” Burmeister,' in 1835, placed the T'Hysanura between the Liotheide and Blattide. He gives for the Poduride the following characters :—‘‘ Antenne corpore breviores, filiformes ; oculi compositi nulli; partes oris abscon- dite, palpi 4 brevissimi, inarticulati, dentati, setigeri ; tarsi 1—2 articulati.” He adopted the genera Achorutes, Poduwra, Orchesella, and Sim ynther us, adding, as already mentioned, a fifth, “ Lipura,’ for the species without a spring tail. This was a decided improvement. He also proposed the name Choreutes for the species of Podwra with Jong antenne, at the head of which he placed Linnus’s P. plumbea. This name has not been adopted by subse- quent writers, having been already used for a genus of insects. In the ‘Comptes Rendus’ for 1836” M. Guérin 1 «Handbuch der Entomologie? 2 ‘Comptes Rendus de V’Acad. des Sciences,’ 1836, vol. ii, p. 595. 14, INTRODUCTION. published a short notice on the abdominal appendages of Machilis polypoda, which he compares with the branchiw of Crustacea, a comparison which, he says, “me semble d’autant plus probable, que Latreille n’a pas trouve de traces de stigmates sur les nombreux individus quw’il a eu occasion d’observer.” In the year 1839 M. Abbé Bourlet published his “Mémoire sur les Podures.”’ He described shortly but with much accuracy their antennee, eyes, and other external characteristics. He divided the Linnean genus Podwra mto five groups, characterised as follows : PODURES. € Antennes longues de trois | articles, le dernier beaucoup Couvertes J plus long que les autres, yeux d@ écailles. formés de six ocelles ; . ler genre, Macrotome. Antennes courtes, de quatre Larticles, huit ocelles : . 2e genre, Lépidocyrte. Antennes de Jongueur mo- yenne, variant de deux a cing articles inégaux, six ocelles . 3e genre, Hetérotome. Antennes courtes, constam- ment de quatre articles A peu Sans pres égaux entre eux, dix ou écailles. huit ocelles. : . 4e genre, Isotome. Antennes trés-courtes, de quatre articles, corps noir, fort petit, organ du saut attaché sous le ventre, et non & son extrémité, huit ocelles . . de genre, Hypogastrure. His genus J/acrofoma contains the old species P. plumbea, and agrees with Burmeister’s Choreutes and Nicolet’s Yomocerus. M. Bourlet was mistaken in supposing that the species forming this genus have only three segments to the antenne. There are normally four, but one is very often wanting, these organs being extremely hable to injury, and the terminal segment, if once removed, being never replaced. This lability to injury on the part of the antenne has led him into another curious error. The genus Hetero- 1 «Mémoires de la Société Royale des Sciences, de ’ Agriculture et des Arts, de Lille.’ INTRODUCTION. 15 toma offers, he says, “‘ une anomalie remarquable. Bien- que leurs antennes soient evidemment conformées sur un méme type, non seulement le nombre de leurs arti- cles est souvent variable, mais ce nombre n’est pas toujours égal dans le méme individu.” ‘This difference between the two antenne, even of the same specimen, ought to have prevented him from characterismg a genus on such merely accidental characters. His last genus, Hypogastrura, is founded on the Podwra aquatica, for which species it seems better to retain the old genericname. M. Bourlet also describes a number of new species, and concludes with some general remarks on the habits of the group, which he describes with considerable accuracy, though he is in- clined to regard them as viviparous, which is a mistake. His other two proposed genera, Lepidocyrtus and Isotoma, have been generally adopted. The following is a list of his species : Macrotoma plumbea == Tomocerus plumbeus. a nigra is nigra. ss longicornis - longicornis. A ferruginosa : a nigra. Lepidocyrtus curvicollis Lepidocyrtus curvicollis. Heterotoma flavescens Orchesella rufescens. Fe villosissima 3 villosa. e livida P 3 crystallina Templetonia crystallina. Fe grisea Orchesella villosa. as pulchricornis cincta. 9 musci 9 ” FY vaga és : ‘s septempunctata 5 6 ie quadripunctata os ” cincta ” ” Tsotoma villosa - villosa. i viridis Isotoma viridis. a cerulea is 5 - bifasciata i aquatilis. ‘a trifasciata ” ” 4 arborea 45 arborea. . nivalis Degeeria nivalis. a rubricauda Tsotoma arborea. 3 cursitans Degeeria nivalis. S feenestrarum , tenestrarum. . fusiformis Degeeria nigromaculata. _ violacea Lepidocyrtus violaceus. Hypogastrura aquatica Podura aquatica. 16 INTRODUCTION. I will now proceed, though somewhat out of chrono- logical order, to M. Bourlet’s second memoir, ‘Sur les Podurelles.’! A great part of this memoir is merely a reprint of the preceding. The species described are as follows: BovurteEt, ‘ Mém. Soc. Roy. Douai.’ Macrotoma plumbea os spiricornis Lepidocyrtus curvicollis 5 argentatus $3 rivularis ZKitheocerus rufescens a8 crystallinus se griseus e pulchricornis a cinctus i rubrofasciatus ye quinquefasciatus 5 dimidiatus aquaticus 39 Podura villosa . viridis 3 bifasciata - trifasciata rs arborea i nivalis 4A annulata . palustris . cursitans 4 argenteo-cincta violacea Hypogastrura murorum aquatica is agaricina - fusco-viridis Adicranus fimetarius = corticina Sminthurus viridis . fuscus i bilineatus - aquaticus 50 lupulinze _ pallipes Dicyrtoma atropurpurea a dorsi-maculata Tomocerus plumbeus. » longicornis. Lepidocyrtus curvicollis. 1 lignorum. geneus ? Orchesella rufescens. Templetonia crystallina. Orchesella villosa (young). = cincta. 393 99 3 rufescens. 99 39 9 39 Isotoma palustris. Orchesella villosa. Isotoma viridis. = aquatilis. EBD 99 ap arborea. Degeeria nivalis. i, annulata. Isotoma palustris. Degeeria nivalis. Seira platani. Lepidocyrtus violaceus ? Achorutes murorum. Podura aquatica. Achorutes cyanocephalus ? x sunilatus P Lipura fimetaria. 39 2 Smynthurus viridis. “ fuscus. - oblongus ee aquaticus. lupuline. _ pallipes. — The table of genera differs, however, considerably from that in the previous memoir; it is as follows: ‘Mémoires de la Société Royale de Douai’ for 1843. INTRODUCTION. 17 PODURIDES. ( Antennes longues, de trois Couvertes __| articles, le dernier beaucoup PAeailles plus long que les autres ler genre, Macrotoma. Antennes courtes, de quatre articles . : : : . 2e genre, Lepidocyrtus. ( ( Antennes de longueur moy- enne, variant de deux a cinq arti- cles inegaux . 3e genre, Aitheocerus. Antennes cour- tes, constam- Sans Un organe ate de quatre écailes, 1 saltatoire . 2tticles & peu prés égaux . de genre, Podura. Antennes trés courtes, de qua- tre articles, or- | gane_ saltatoire attaché sous le ventre, et non a (son extrémité . 5e genre, Hypogastrura. Point d’organe saltatoire . 6e genre, Adicranus. Here he has substituted the term Atheocerus for Heterotoma, repeating, without the least misgiving, his curious error about the antenne; he abandons the term Isotoma, replacing it by the old generic name Podura; and he proposes a new generic term, Adi- cranus, Which, however, is synonymous with Burmeis- ter’s Lipura. The Siynthuride he divides into two genera, charac- terised as follows : Smynthurus.—Antenne four-joited; no dorsal tu- bercles. Dicyrtoma.—Antenne eight-jointed; two dorsal tu- bercles. Of the former, he describes six species, four being new ; of the latter, two species, both new. I have sometimes been disposed to regard Dicyrtoma as sy- nonymous with my genus Papirius. In this case, however, M. Bourlet is mistaken in regarding the antenne as eight-jointed. 2 18 INTRODUCTION. In both his memoirs M. Bourlet gives many details concerning the external organisation and habits of the Collembola, but it is much to be regretted that he was not more conversant with the literature of the subject. Lucas' places the THysanura between the Myriapopa and the Anoprtura, adopts Templeton’s genera Or- chesella and Achorutes, and describes the following species :—Orch. filicornis, Tem. ; O. cincta, Tem.; Or. succincta, Guérin (which appears to consist of the very dark specimens) ; Podwra arborea, li. ; viatica, L.; plumbea, L.; villosa, L.; annulata, Fab.; aquatica, L.; nivalis, L.; cincta, L.; lignorwm, Fab.; pusilla, L.; vaga, L.; ambulans, L.; monwra, Schrank ; fime- taria, Li.; nitida, Tem.; mgromaculata, Tem.; albo- cinete, Tem.; cingula, Tem.; fuliginosa, Tem.; fas- ciata, Say; bicolor, Say; iricolor,- Say; Aver utes dubius, Tem.; muscorwm, Tem.; maritimus, Guér. ; Smynthurus signatus, Fab. ; viridis, Geof.; polypodus, L.; ater, L.; fuscus, Lacord. and Boisd.; gutiatus, Say. bf the Lepisnvide he recognises three genera, Machilis with three species, Petrobius with one (our M. mariti- nus), and Lepisma with eleven. In the ‘Annales de la Société Entomologique de France’ for 1842, M. Waga described * a new Achorutes under the name of A. bielanensis. This species does not appear to have been as yet met with in Western Kurope. The ‘Transactions’ of the same society for the following year contain a memoir by Mr. H. Lucas, ‘Sur les travaux qui depuis Latreille ont été publiés sur ’ordre des Thysanures, et particuliérement sur la famille des Podurelles.”* It does not contain any ' «Hist. Nat. des Crustacés, des Arachnides et des Myriapodes,’ 1842. 2 “Description d’un insecte aptére qui se trouve en quantité aux environs de Varsovie.” Par M. Waga. ‘Ann. Soc. Ent. France,’ 1842, p. 264. 3 «Ann. Soc. Ent. France,’ 1843, p. 269, INTRODUCTION. 19 original observations, but is carefully executed, and fully answers to the title. Mr. Templeton’s memoir’ on the genus Cermatia, and some other exotic Annulosa, contains a description of a new species of Lepisma, for which he proposes the name L. niveofasciata ; some observations on Linneeus’ LL. polypoda, which he considers may perhaps prove to be the species now known as Machilis maritimus ; and some remarks on the relations of Lepisma to Podura. _ In the same year M. Nicolet published his ‘ Recherches pour servir a l’histoire des Podurelles,’ one of the most important contributions to our knowledge of the eroup which has yet appeared. In this excellent memoir M. Nicolet gives a full account of the external and internal anatomy of the group, and describes each species in detail. The plates, which are nine in number, are well executed, and many of the species are carefully coloured. Unfortunately MM. Nicolet and Bourlet were ignorant of one another’s labours, and in many cases the same species is described by them both under different names. M. Nicolet gives (p. 6) the following table of the genera :— 1 «Trans. Ent. Soc. London,’ 1842, p. 304. 2 ‘Nouveaux Mémoires de la Société Helvétique des Sciences Natu- relles,’ 1842. eee eee on ssaunyquhug say ‘Teraqryt odnoas *sa]JaSayolQ ST + awd xnet 9 a ee *Teaaqey odnows sawwaabhaq aT { Sait SO ‘Teroqvy odnor3 "salan0uUloy, Sa ‘ iL Th wed xnof J ‘Te1oqvy odnoas ‘samapoydhg sa'T { avd xnef g *‘saiuosarqy 8a ‘Teraqey odnois *[eraqyey odnors ‘saunpod 8a'T ie xnak g “OTVIIVA 9.1q ‘sasoydouup sat { -wou ua xnex 4 ‘Ter94e, odnoas ‘SAINLOYIP SIT { aed anek op | op wee eee “WOPT “Wa pT “wWepyT “mopy “aopy “WlapT ‘sama Xorq $04 | -dasul £saatoyo | “wut saqT *saMaoNs $940aS “UI § SaqIOYORUL ymog J eee . 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The genus Achorutes of Templeton was founded for species in which the spring is present, though small, and must, of course, be retained for these, as M. Nicolet himself subsequently admitted. Nicolet’s name PoDURIDES Achorutes ‘ >, 2 Tomocerus : uzekS Cyphoderus. kd Anurophorus . ee) Anoura. 5 Se sh) 176 131 I think, however, that the consolidation of species might with advantage have been carried even further. He also presents the following table of the genera : ro oO i 4 | | : (Des filets sétiformes 4 l’extrémité postérieure de abdomen. Les Lépismides . 4 Point de filets sétiformes, mais souvent une L { queue fourchue repliée sous le ventre et servant au saut. Les Podurides Corps pourvu Wécailles . Corps dépourvu d’écailles Filets terminaux inigre corps subcylin- drique A Filets darmitiate égaux, corps “déprimé ; Trois filets terminaux : Deux filets terminaux . : 3 (Un appendice saltatoire en dessous de l’ex- tremité postérieure de Pabdomen et com- posé d’une tige plus ou moins longue ter- minée par deux filets quelquefois : arqués, le plus souvent droits Point d’appendice saltatoire en dessous de . 14 Vabdomen. Les Inpurelles Corps subglobuleux sans segments apparents. Les Smynthurelles Corps subcylindrique a segments apparents. Les Podurelles . s 3 C Antennes coudées de quatre articles, point de tubercules sur le dos de l’abdomen . Antennes coudées de huit articles, deux tuber- cules sur le dos de labdomen GENRES. Machilis. Lepisma. Nicoletia. Campodea. Smynthurus. Dicyrtoma. INTRODUCTION. _ 27 GENRES. Corps composé de neuf segments apparents . 9 Corps composé de huit segments apparents . 10 oo ( Appendice saltatoire trés court, a filets larges | et légerement arqués, sommet ar rticulé ; Achorutes, 9. 4 Appendice saltatoire un peu allongé 4 filets L étroits cylindriques, fortement arqués et biarticulés : : 5 : : : Podura. Tétedirecte, ou insérée a Vextrémité antérieure 10 du thorax . ; = dtl * ) Téte inclinée ou insérée en dessous de Vextré é- mité antérieure du thorax ; ‘ . 13 Al Antennes de quatre articles . ; : ~ £2 * ? Antennes coudées de six articles . , : Orchesella. Appendice saltatoire & base plus courte que 12 les filets . ; . TIsotoma. Appendice saltatoire a base égale en longneus aux filets . 3 : : . Degeeria. 13. longue que les filets . ; : Cyphoderus. Appendice saltatoire biarticulé 4 base plus Appendice saltatoire trés long et triarticulé | Tomocerus. ( Des machoires, corps non tuberculé, peu ou | point velu, yeux variant en nombre dans ; chaque espéce . : Anurophorus. Pas de machoires, un siphon, cor ps “tuber culé, | non écailleux peu velu, a ie par L groupe latéral . " : Anoura. 14, In 1849 M. Lucas published his ‘ Exploration Scientifique de l’Algerie.’ He described six species of CottemBora, all of which he regarded as new, although three at least seem to be identical with Huropean forms. M. G. Frauenfeld’ in 1854 proposed a new genus, Tritomurus, for a blind species found in the cave of Treffen. It is most nearly allied to Tomocerus, but, in addition to the absence of eyes, differs in the constitution of the spring, which possesses an additional segment. M. Kolenati” has described a second series of Tvito- murus, under the name of Tritomurus macrocephalus. 1 ¢ Verh. d. Zool. Bot. Vereins in Wien,’ 1854. 2 «Sitz. des k. Ak. d. Wiss. Wien,’ 1858. 28 INTRODUCTION. This species, however, differs greatly from the generic description given by Frauenfeld, particularly in the appendages of the head, the true nature of which I cannot understand. In 1854 M. H. L. Elditt’ published an “ Hinleitung zur Monographie der Thysanuren,’ being an analysis of the memoirs by Nicolet and Bourlet. In the followmg year M. Brauer* mentions the presence on snow of a Podwra which he refers to the Isotoma saltans of Agassiz. I have been unable to see M. Papon’s note, “* Ueber eineim Februar, 1855, bei Chur beobachtete Desoria.’” In 1858 M. J. A. Herklots* proposed the name of Degeeria pi for the Podura arborea grisea of De Geer, which, he observes, is quite distinct from the D. n- valis. His observations on the subject seem to me perfectly correct, but both his name and also that of P. nigromaculata, proposed for the same species by Templeton, must give way to the far earlier one of D, annulata. In the same year M. Low’ published a note on a Podura found in considerable numbers on the surface of snow. He refers it to the Achorutes murorum of Gervais, which I consider to be identical with the A, dubius of Templeton. He observes that out of 104 European Poduride, 24 have been observed on the surface of snow. M. Kolenati® gave, also in 1858, an abstract of Nicolet’s classification of the group, and a list of the species. In this country the study of the CottemBo1a has been singularly neglected. Infact Mr. Templeton’s was the only memoir on the British species which had appeared 1 « Bntomologische Zeitung,’ 1854. 2 ‘ Verhandlungen des Zoolog. Botanis. Vereins. Wien,’ 1855. 3X « Jahr. d. Nat. Ges. Graubundens,’ 1856. 4 «Mémoires d’Entomologie de la Soci¢té Entomologique des Pays Bas’ for 1858. 5 * Verh. der k. k. Zool. Bot. Gesellschaft ’ of Vienna, 1858. 6 «Wien. Entomol. Monat.,’ Bd. 2, No. 5. INTRODUCTION. 29 until the year 1863; while, as regards England, I have only met with the casual mention of two species, Podura plumbea and Smynthurus fuscus, in Samouelle’s ‘ Ento- mologist’s Useful Compendium.’ In the above-mentioned year I published my first memoir on the CoLtemsona, which was followed by a second in the year following, a third in 1867, and a fourth in 1869. In these memoirs I have recorded about sixty Hnglish species, and have given some account of their habits and anatomy. As regards the latter, I differed in many important points from Nicolet, to whom we were indebted for the first account of their internal organisation. For imstance, as regards the digestive organs, | found myself compelled to question the presence of Malpighian vessels. Again, with the exception of Simynthurus, | found to my surprise that the Contemsona had no trachez, while Nicolet figured a complete system of them in Podura, and apparently considered that a similar arrangement prevailed throughout the group. These questions, however, are more fully considered in the chapter devoted to anatomy. M. de Olfers, in his ‘ Annotationes ad anatomiam Po- durarum, Dissertatio inauguralis,’ adopted, for the most part, the views of Nicolet. He was not, however, acquainted with my memoirs. In 1865 Dr. F. Meinert,' of Copenhagen, published an excellent memoir on the Campodew, which has been translated in the ‘ Annals and Magazine of Natural History’ for November, 1867. Dr. Meinert incidentally mentions that he agrees with me as to the respiratory organs of the CoLLEMBoLa, but the principal part of the paper is devoted to the consideration of the mouth parts. He points out that the mouth of the Contempona differs from both of the principal types found amongst insects. T’he mandibles and maxillz do not articulate with the skull by means of a hinge-joint, as in all other mandibulate insects, 1 « Naturhis, Tids.,” 1865. ‘Ann. Mag. of Nat. His.,’ 1867. 30 INTRODUCTION. but ‘are retracted within the cavity of the skull, so that only their apices are visible outside the mouth ; but nevertheless they are calculated for biting, capable of being moved laterally against each other,” and differ, therefore, essentially from those of the suctorial eroups. ‘This intermediate type is amongst insects only found in the THysanura, and affords one of the two principal characters of this order or suborder, the other being this, that they remain in the larval stage without undergoing any metamorphosis at all.” He excludes the Lepismide, therefore, from the THysanura, although the articulation of the mandibles approximates to that of Podura. Lastly, in 1869, M. Tullberge published a valuable monograph of the Lipuride, in which family he includes Achorutes. For reasons which will be given presently, I am unable to agree with him in this. Having thus very briefly referred to the principal memoirs which have appeared on the Thysanuwra and Collembola, I will now proceed to consider the arrange- ment and position of these two groups. CHAPTER I. ON THE CLASSIFICATION OF THE COLLEMBOLA AND THYSANURA. Linnzvs placed his genera Lepisma and Podwira immediately after the Diptera, and at the head of the Aptera, followed by Termes, Pediculus, Pulex, Acarus, Phalangium, Aranea, Scorpio, Cancer, Monoculus, Onis- cus, Scolopendra, and Julus, in the above order. The system adopted by Geoffroy was very similar. He classed Podura and Lepisma, however, between Pediculus and Acarus. Fabricius, on the contrary, on account of the struc- ture of their mouths, united them with the Neuroptera, in his order Synistata ; and in-this view he was followed by Blainville. The order T'ysanura was established in 1796 by Latreille, who placed it between Pulex and the Para- sira. In the ‘Considérations Générales’ (1810), he arranged it with the Myrrapopa and Parastta among the AracunipA. In 1829, however, he regarded it as the second order of Insects, placing it between the Myrtaropa and the Parasira. Lamarck, in his ‘ Animaux sans Vertébres,’ adopted the group Tuysanura, which he united with the Myria- ods to form his Arachnides Crustacéennes, constituting the first section of his Arachnides antennées-trachéales. He even regarded the 'T'HysaNuRA as more nearly allied to the Crustacea than to the Insecta; they are, he said, ‘“‘ assurément point des Crustacés et encore moins des Insectes.” In separating them thus widely from the ae CLASSIFICATION. other Hexapods, he seems to have been mainly in- fluenced by the absence of metamorphoses. Cuvier, on the contrary, regarded them as true insects, and arranged them as the second order, pre- ceded by Myrraropa, and followed by the Parasira. Von Siebold does not adopt the order THysanura, but considers that the two families of Lepismide and Poduride, together with the Pediculide and Nirmde, form the order Aprrra, which he regards as the first among the true Insects, the Myriaropa forming, in his system, part of the Crustacga. Burmeister, in his ‘Handbuch der Entomologie,’ treated the THysanurA as a separate tribus, which he placed between the Mallophaga and Orthoptera. According to Bourlet, the Tuysanura follow the Myriapods, “and constitute the first order of insects. Macleay classed them with the Myriapods, and Lice among his Ametabola. Lucas adopted Laporte’s name of ‘* Monomorphes” for the Tuysanura, and placed them between the Myriapods and the Anoplura. M. Gervais, in the ‘ Histoire Naturelle des Insectes Aptéres,’ points out the great diversity which exists between the Lepismide and the Poduride. Referring to the classification of Fabricius and Blainville, who placed the ‘T'uysanura amongst the Neuroptera, he says, ‘‘ Les Thysanoures ainsi envisagées sont done des Névroptéres frappés d’un arret de développement. C’est ce que nous admettons parfaitement pour les Lepismes et genres voisins, mais il nous parait impossible d’en dire autant, ou du moins dans le méme sens, pour les Podures. Le petit nombre des anneaux du corps des Podurelles les rapproche des Insectes épizoiques, et le reste de leur organisation difftre completement de celle des Lépismes. I] serait donc plus convenable de créer a leur intention un ordre particulier parmi les Insectes hexapodes, dont le corps n’a pas le nombre nermal danneaux. Nous laisserons a cet ordre des Podures et des Smynthures le nom de Podurelles, c’est a dire qui ——— CLASSIFICATION. oO saute avec sa queue, puisque cest la un de leurs earacteres les plus généraux. Gerstiicker, in the ‘Handbuch der Zoologie,’ places the Counemsona amongst the Orthoptera, on ‘account of the absence of metamorphoses, and the mandibulated mouth. Latreille, in his ‘‘ Essay on the THysanura” in the ‘Annales du Muséum,’ vol. i, p. 161, says—* Par la masse de leurs caractéres, les Thysanoures appartien- nent a la classe des Insectes. © La composition du thorax, des organes de la locomotion, et de la bouche, Vindiquent suffsamment. A légard meme de ces dernicres parties ; et surtout de ’oviducte extérieur du plus grand nombre de femelles, les Thysanoures ont la plus grande affinité avec divers Orthopteres. Mais sous d’autres considérations, comme l’absence de méta- morphoses, les organes de la vision, les appendices abdominaux et les habitudes, ils se rapprochent aussi des Myriapodes et des Arachnides. D’aprés un tel mélange de rapports, il est naturel de conclure que ces animaux font la transition des Myriapodes aux Insectes, et que vu leur plus grande ressemblance avec ceux-cl, ils doivent ¢tre placés a leur téte. Point de transfor- mations, abdomen terminé par des soies, tel est, suivant le docteur Leach, le caractére essentiel de ordre des Thysanoures ; mais 11 nous semble, par son extréme concision un peu trop vague; et aussi d’écarter tout embarras, nous le sionalerons ainsi; point de méta- morphoses, ni de stismates apparents ; corps générale- ment recouvert de petites eécailles, avec Vabdomen terminé par trois filets ou par une queue fourchue servant a sauter.”’ These do not, however, appear to me to be the real characteristics of the group. ‘The absence of meta- morphoses must be taken for what it is worth. Spira- cles are present in the Lepismide and in Smynthurus, but are wanting in the majority, if not the whole, of the Papiriide, Poduride, and Lipwride. Scales do not occur either in the Siynthuride, Papiride, or Lipuride, od CLASSIFICATION. and are wanting in several genera of Poduride. Lastly, the saltatorial appendage is absent in the Lipuride, and though present in all the Smynthwride, Papirtide, and Poduride, we must remember that the saltatorial appendage of Poduwra and Achorutes 1s not, in fact, homologous with that of the other genera, an important point, the significance of which has been overlooked by previous authors. Again, the mouth-parts of the Lepismide and Po- duride are constructed on a totally different plan. Dana!’ regards the Tuysanura and CoLLeMBona as true insects, but as forming one of three great groups mto which that class may be divided, namely— Ptero-prosthenics, or Chenopters, including the Hy- menoptera, Diptera, Aphaniptera, Lepidoptera, Homoptera, Trichoptera, and Neuroptera ; Ptero-metasthenics, or Elytropters, comprising the Coleoptera, Hemiptera, and Orthoptera; and thirdly, The Thysanura. It appears to me that the two former groups are more nearly allied to one another than they are to the third; or, at least, to that portion of the third group for which I have proposed the name “‘ ConLEMBona.” As regards other Apterous groups of insects, Dana himself observes’ that ‘the apterous Pediculi, as Nitasch long since observed, have no characteristics that would separate them from Hemipters, and the Nirmids none that would remove them from the Orthopters. They are simply inferior wingless species of those types, as much as the Coccids are of Homopters, and they have nothing of the agility of the Lepismids. There are no points of structure indicating an affinity to any two or more of the higher subdivisions of insects, or to the inferior Myriapods; they are not wrosthenic, bemg in no way essentially different, as regards their legs, from the types to which they are referred.” ' « American Journal of Science,’ January, 1864, 2 ‘Loe. cit., p. 26. CLASSIFICATION. 30 The points which we have principally to consider in relation to the classification and position of the Trysa- NuRA and ContemBoLa are—the absence of metamor- phoses ; the absence of wings; the presence or absence of trachee ; the structure of the mouth; the saltatory appendage; and the ventral tube. The last-mentioned organ, though observed by most of the preceding writers, has not, I think, attracted the attention it deserves. It 1s, in fact, the true charac- teristic of the group. The absence of wings and of metamorphoses is not peculiar to the CoLLEMBoLA; in fact the presence of metamorphoses is closely connected with that of wings. To the tracheze we must not attach too much importance ; for though absent in the great majority of the group, they occur in Smynthurus. The pecuhar mouth-parts of the mandibulate genera are entirely absent in Anwra ; and the caudal appendage is wanting in the Inpuride. Thus, then, the ventral tube is characteristic as being general to the species belonging to the Linnean genus Podura, and still more so, as being peculiar to them ; at least, I know of no similar organ in any other group of Articulata. The presence of trachezx, the structure of the mouth, and the saltatory appendage, all indicate a wide distinction between the Lepismide and the Podwiw, and, when considered in conjunction with the fact that the ventral tube 1s absent among the former, force us to the conclusion that the two groups are much less closely allied than has hitherto been supposed. This was, indeed, fully recognised by M. Gervais,’ whose remarks on the subject I have already quoted (ante, p. 32). Mr. Templeton has also expressed the same opinion. He observes that? * the Lepismide should be separated most markedly from the other division of _ the T'aysanura with which they are usually associated ; the antennz, caudal apparatus, and more especially the 1 ©Loe. cit., vol. 11, p. 378. 2 «Trans, Ent. Soc. London,’ 1842, p. 305. 36 CLASSIFICATION. mouth (and the habits of the animals), having nothing in common.” We must, indeed, in my opinion, separate them entirely from one another; and I have proposed for the group comprised in the old genus Podwra the term CoLLEMBOLA, as indicating the existence of a projection or mammilla enabling the creature to attach or glue itself to the body on which it stands. We now come to consider whether this group should be classed among the Insecta, or whether Lamarck was right in separating it from that great class. Taking each of the characteristic points separately, we begin with the absence of metamorphoses. ‘To this we must not attribute too much importance. ‘There are species of Orthoptera and of Neuroptera which are almost in a similar position. So, again, as regards the absence of wings, the same argument holds good: in all orders of insects there are wingless species. Moreover, although it may seem paradoxical to say so, the character of an organ is of greater classificatory value than the absence of it. Thus, for instance, we have cattle and deer without horns, but no cows have deer’s horns or vice versd. So the presence of four wings is absolutely peculiar to the Insecta; but some insects have only two wings, and in all the large orders there are species without any wings at all. The absence of wings is therefore no conclusive evidence against classing the Cornnempota amongst the Insecta. The absence of tracheze is more significant. That of wings involves only inability to fly, but that of trachez implies that respiration is carried on in a different manner. ‘The importance, however, of the difference is reduced to a minimum, because there are no other special organs for respiration, and the process seems to be carried on through the skin. Moreover, while Papirius, like most of its allies, has no trachee, Smynthurus has a well-developed system. I know hardly any other case of species, so closely resembling one another in other respects, differing so entirely as OLASSIFICATION. 37 to one of the most important parts of their internal anatomy. The structure of the mouth, as far as it goes, is unfavorable to the view of those who regard the CoLLEMBOLA as true insects. I quite agree with Dr. Meinert that the mouth differs essentially from both the principal types found among insects, without, how- ever, making any near approach to that of the Myria- poda or the Arachnida.' The presence of a saltatory caudal appendage must be taken into consideration. It is very remarkable that no similar apparatus 1s possessed by any one of the almost innumerable insects, many of which, how- ever, possess the power of leaping in a high degree. Nor, on the other hand, do any of the CoLLemBota jump hke Gryllus, Haltica, or Pulex, by means of their hind legs. The true value of such a character as this, how- _ ever, is as difficult to estimate as it is easy to apply. The same observations apply to the ventral tube, which, as I have already observed, is even more charac- teristic of the CoLLempona than the caudal appendage. As the upshot of all this, then, while the CottnmBona are clearly more nearly allied to the Insecta than to the Crustacea or Arachnida, we cannot, I think, regard them as Orthoptera or Neuroptera, or even, in the strictest sense, as true insects. That is to say, the Coleoptera, Orthoptera, Neuroptera, Lepidoptera, &c., are, In my opinion, more nearly allied to one another than they are to the Poduride or Smynthuride. On the other hand, we certainly cannot regard the CoLLuMBona as a group equivalent in value to the Insecta. If, then, we attempt to map out the Articulata, we must, I 1 Tsay any “near” approach, because, as Mr. Humbert has pointed out to me, the mouth-parts of Scolopendrella in some points approach those of the COLLEMBOLA. This genus, indeed, appears to be more interesting and peculiar than either Gervais or Newport supposed. For instance, it has on the underside of each segment a pair of appendages closely resembling those of the Lepismide—a fact which suggests doubts whether the subabdominal appendages of that group really represent the legs of Myriapoda. : 88 ' CLASSIFICATION. think, regard the Crustacea and Insecta as continents, importance, but and CoLLemBona as islands—of less the Myriapoda still detached. Or if we represent the divisions of the Articulata like the branching of a tree, we must picture the CoLLEm- BOoLA and T'HYSANURA as separate branches, though small ones, and much more closely connected with the Insecta than with the Crustacea or the Arachnida. From the poit of view which we occupy the extre- mities alone of such branches are visible, and, con- sidering the delicacy of the Contempona, and the consequent improbability that we shall ever acquire any satisfactory knowledge of the extinct forms, it is not likely that the connecting stems will ever be fully known to us. The classification of the Contempoia adopted in the present work is shown in the following table. As a matter of convenience, no doubt, several of the proposed families might be consolidated. The charac- ters, however, by which they differ from one another are of considerable importance, and the great object in all classification should be to attain to the most natural system. Moreover, as far as the paucity of species is concerned, we must remember that the number will doubtless ere long be considerably increased. EV Ree ‘puausidaT ‘pusidaT Ee OUUNG ‘papodupy -ahdvp “‘DUnour “mindy “DUNpoge *saynLoyopr *DUWLOJOST prsaabay ssnguhoopriday { “DAVY “pryoagr *pruoja)duaT, “SNMNUW OPN T, “SNLIIOWOT, { “01 aSAY INO “snunyquhugy “purogwhougy sniudng Ren i no [BL10}VIVG eee ert eee eweresone qaoys ee ee meee , eprusidey *e Aywag see pmscocecenveesness Suot soSupneddey [epneg \ [BL10}84[BS- WO BOD GBB SUCGOO TEE Ga sGuCC-B US QORuOL Yio a PBC OOOOUUUOCONs iy) “cc “ec Ge od ep ee ae eh ee ; ‘ ; eres aeeseeeeeeeescteceeettaeentoneereccereresraes Ona (SaTLOUURLY ae epvopodurg *g Apu | | *VHONVSAHY, BESIAICROOOIOGOOIOOIOOCIUCUICIOOIOOOIOIOOIOCOICUIOIOCIOOUIOIOCIOO OOO OICOOIOOOOOCICOOIOOOCIOOOOCOO OOO COOCOM CIO UOOCCICIOOIOCOIOOT ORCS O OCIS COO ei ci icin apisider orf Ayvugr } ee eeeeneesneeereeeereneerieaeereeesrereereereersess QaMMGIpUBUL YIMOPL TT TRMOWNATES-MON “* aprandyy *¢ Apeunyg Oe eee eee ee Serer errr eee eee eee ere eee eee eee ee ee ee eee meee twee MO ONO IIA Joaq |... ceseeeceseeescvasssasssceseseessetensesenscissreensesasaetecteceoaeereceneetereeeetg a Bry OA UAL 4907 aplinpog "Pp Apeuwngy vroereeeeeee enbaqns teers ga TgUt fe q closes: a oe [eurmopqy Bo[mos:snoHatAAy) “* xB1oyy Jopun payeao 7 | -09 sso] 1O o1ouL proxy | t vases = NasOdxo) PRATT oydunts autey >) i soko UGTA ae jo quout Sa Gem NeA RD Sonchd. iitchte | settee eeeeeeteeeeeeeeres Gag on J -Sas [vuluty, | £r0qRq Tes so ord utis qUaULses PaAIyLy, | B OJuL podoT | soqvos wad r-oAep quem f+ epritoeseq ‘g Apu | -Sos [evurut | | eeeeeetonaeaeceeeerersrrrssecssseersasecsseevesereeereres THTTOIONS YANO oT [RILOYVITes-UONT *** 2pranouy *9 He, | | “+ pazutof-g | c ‘VIOdNATION) uasqe sof’ creat @ [ +++" paSuta posuts euuey dnoas yove spioutses | -ue jo quour -opqe paryy ur 2 sody) [eurmi, omy, ) -Sos [eurutey, jo esupueddy ) soanesnonnocnecccn hon oan sisats sacs sedei dvdr Uvenmenectaas numuanaace™<' nan CTO IG xuuoquy J Pe eee eee e eee e rere tte ee tetas eee t steer ees rss eee ens tee eessesees eee meee tenet eee eet e ee eee eee essere seneeeeeesiseee epinyqutug a4 hyn Misioieleteiciniciaie eteieistnclereieionstaaiere(ern cis aaveteistatoroli's sits stotelcteveretertorsVaieleeteraleietelele(eralsvetarevehiiere (cir sisferatoteleleroletse poqurol-g « Pr EeN ses | Feo cae e cS ace 115 SERRE PURE cron or adcoerg @OiOic ance ULC ona MMO ACAI NETITIG Ife me des eh MATE MEAN) CHAPTER III. ON THE IMPORTANCE OF THE COLLEMBOLA AND THYSANURA IN RELATION TO THE EVOLUTION OF THE INSECTA. Tue Trysanura and CoLLeMBoLa possess a peculiar interest from the position which they appear to occupy in the evolution of insects. ‘ It has always seemed to me that the metamorphoses of insects are among the principal difficulties of the Darwinian theory. ‘Take, for instance, the life-history of a butterfly. It commences as a caterpillar, with powerful jaws adapted for cutting and masticatmg leaves, then passes through a period of fasting, and in its perfect condition has a very complex suctorial mouth. I omit for the present the consideration of the development of wings and the changes in the in- ternal organs. Now, how can such a case have arisen P It is obviously not an instance of continuous evolu- tion, because a mature Arthropod can never have re- sembled the mouthless, motionless, imbecile Pupa. I have often wondered that the opponents of Mr. Darwin’s views have not dwelt on these facts, which prima facie appear to present a strong argument against the theory of evolution. On this interesting problem the Contempona and the TrHysANURA seem to me to throw much lght. I have already discussed it briefly in my memoir on the development of Chloeon,' and it has also been handled by F. Miiller, Haeckel, Brauer, and by Mr. Darwin himself. : 1 «Zinn. Trans.,’ 1863 and 1865. THE EVOLUTION OF THE INSECTA. Ad Fritz Miller is of opinion’ “that the most ancient insects approached more nearly to the existing Orthop- tera, and, perhaps, to the wingless Blattide, than to any other order, and that the complete metamorphosis of the Beetles, Lepidoptera, &c., is of later origin.” There were, he adds, ‘‘ perfect insects before larvae and pupe.’ The following passage gives his views so clearly, and 18 so interesting, that I need no apology for quoting it entire: ‘The order Orthoptera, including the Pseudo-neu- roptera (Hphemera, Libellula, &c.), appears to approach nearest to the primitive form of insects. In favour of this view we have— ‘1. The structure of their buccal organs, especially the formation of the labium, ‘ which retains, either perfectly or approximately, the original form of a second pair of maxille ’ (Gerstiicker). “2. The segmentation of the abdomen. «3. That, asin the Crustacea, the sexual orifice ‘and anus are placed upon different segments ; ‘ whilst the former is situate in the ninth segment, the latter occurs in the eleventh’ (Gerstiicker). ‘4, Their paleontological occurrence; ima fossil state the Orthoptera make their appearance the earliest of all insects, namely, as early as the Carboniferous formation, in which they exceed all others in number (Gerstiicker). *°5. The absence of uniformity of habit at the present day im an order so small when compared with the Coleoptera, Hymenoptera, &c. For this also is usually a phenomenon characteristic of very ancient groups of forms which have already overstepped the climax of their Cen and is explicable by ex- tinctionin mass. . ** If from all this it seems right to regard the Orthop- tera as the order of insects approaching most nearly 1 «Facts for Darwin,’ p. 118. 42 RELATION OF THE LARVA TO THE IMAGO. to the common primitive form, we must also expect that their mode of development will agree better with that of the primitive form than, for example, that of the Lepidoptera, in the same way that some of the prawns (Penéus), approaching most closely the primi- tive form of the Decapoda, have most truly preserved their original mode of development. Now, the majority of the Orthoptera quit the egg in a form which is distinguished from that of the adult imsect almost solely by the want of wings; these larve then soon acquire rudiments of wings, which appear more strongly developed after every moult. Even this perfectly eradual transition from the youngest larva to the sexually mature insect preserves in a far higher de- eree the picture of an original mode of development, than does the so-called complete metamorphosis of the Coleoptera, Lepidoptera, or Diptera, with its abruptly separated larva-, pupa-, and imago-states. “ ‘Origin of Species,’ 4th ed., pp. 14 and 97. CHAPTER IV. COLLEMBOLA. General Description. In the CoLLEmpBona, as in true insects, the body is divided into three distinct sections—the head, thorax, and abdomen. The head bears the antennz, the eyes, and the mouth-organs ; to the thorax are attached the three pairs of legs; to the abdomen, the sucker, the catch, and the saltatorial appendage, or spring. The skin is clothed with hairs, and in several genera with scales. In addition to the ordinary hairs, which are of various lengths, some genera bear others of peculiar forms ; for instance, Degeeria has club-shaped hairs (Pl. LXV, fig. 8), and others which more or less resemble a bow (Pl. LXV, fig. 7), not only in the general form, but in having a notch at the end, closely imitating that by means of which the bowstring is attached. Several species also have on their feet, and in some cases, as in Smynthwrus fuscus, on the salta- torial appendage, one or more tenent hairs, that 1s to say, hairs which are swollen at their extremity, and which assist the animal to retain its hold on slippery surfaces. The scales are of very various forms and sizes, even in the same species ; they are generally colourless, but in some species, especially in the genus Lepidocyrtus, are beautifully iridescent. While, however, the scales do not generally offer specific characters either in their form or magnitude, the structure of the scale is often very characteristic. I will not, however, enlarge on this subject, as I shall hope to append a special 56 THE HEAD. chapter on the scales, by my friend Mr. Beck, who has studied them carefully, and than whom no one is more competent to speak on the subject. The head. The head does not generally show any traces of segmentation. In most cases it is somewhat com- pressed from above and below; in others, on the other hand, as in Smynthurus, from in front and behind, thus being, like the rest of the body, mcreased in height at the expense of the length. In Lepidocyrtus the head is attached to the body at an angle, and in some species of that genus the thorax projects so much forwards that when the animal is seen from above the head is completely hidden. The hairs or scales, as the case may be, on the head, resemble those on the general surface of the body. Laboulbéne has called attention’ to a curious organ, which he observed in Lipwra maritima, and wince from its position on the surface of the head—imme- diately in front of the eyes—he proposed to call ‘organ prostemmatique ou ante-oculaire.” Inasmuch, how- ever, as a corresponding organ occurs in some species where the eyes are wanting, Tullberg has suggested,” and I think with reason, that the term “ post- -antennal ” is, on the whole, more convenient. Laboulbéne thus describes this organin Lipura mari- tima (Pl. LXV, fig. 15). It is formed, he says, “‘ par des espaces colorés tels que les représente la figure 7; leur couleur est tres-noire. Le nombre des cercles rapprochés varie de 7 a 8, le plus ordinairement il y en a 7, mais je dois noter que j’en ai trouvé parfois 8 @un céteé et 7 de lautre. Sur les jeunes individus, la disposition est trés curieuse, la figure 9 en donne une idée; il existe alors 22 a 24 espaces comprimés et serrés les uns contre les autres, avec un espace central libre; le tout rappelle la forme du fruit chez les plantes 1 «Ann. Soc. Ent. de France,’ 1864, p. 711. 2 “Om Skandinavisken Podurider,’ Upsala, 1869, p. 14. POST-ANTENNAL ORGAN. Oo” malvacées indigénes, entre autres les Malva et les Althea. Quelque soin que j’aie mis a chercher si du point central il naissait un poil allongé ou toute autre production dermique, je dois dire que je n’en ai point trouvé.” Tullbere suggests, though with some doubt, that the so-called eyes of L. fimetaria are in reality homo- logous, not with the eyes of other ContempBona, but with the post-antennal organs of L. maritima, which they more nearly resemble both in position and in structure. The so-called “ eye” of L. fimetaria consists of minute, circular, colourless, elevations (Pl. LVI, fie. 26), arranged in two almost contiguous rows, and which are only visible under a high power and with a good illumination. Simi- lar organs occur in other species of the same genus, as, for instance, in L. Burmeisteri (Pl. XLV, fig. 16). In- deed, they will probably be found in all the true Lipure. I have always felt a difficulty in regarding this curious structure as an organ of vision, and am disposed to adopt Tullberg’s suggestion. The eyes are situated behind the antennx, on the upper surface of the head. They consist of distinct ocelli, collected together, however, in two groups, one on each side of the head, and generally situated on a dark patch. The number and arrangement of the ocelli afford good specific and generic characters, though in many cases, from their minute size, the curvature and delicacy of the surface on which they are placed, and the hairs or scales by which they are surrounded, they are not very easy to determine. In most cases the ocelli are approximately equal in size, but in some genera one or more are much smaller than the rest. The number and arrangement of the ocelli in the different genera are shown in Pls. LV and LVI. Templetonia has a single ocellus on each side; Orche- sella has six, arranged in the form of an §; Tomocerus and Isotoma have seven; Degeeria, Lepidocyrtus, Simyn- thurus, and Papirius, eight. 58 EYES. The number is noty however, always the same im all the species of a genus. Thus, Lipwra maritima has five ocelli on each side, while L. laricis, according to Nicolet, has eight. Lastly, Beckia and Tritomurus have no eyes. The antennz are situated on the upper surface of the head in front of the eyes. They vary considerably, and offer useful generic, as well as specific, characters. We may consider the normal antenna as consisting of four equal segments. They are generally situated on a more or less salient tubercle, which, in some cases, might be regarded as an additional segment. In Sinynthurus (Pl. LV, fig. 1) the basal segment of the antenna is short, the other three successively increasing in length, each being nearly double as long as its prede- cessor. The terminal seement is divided into more or less numerous subsegments. In Papirivs, on the contrary (Pl. LV, fig. 5), the apical segment, though similarly subdivided, is httle longer than the basal. In Dicyrtoma the antenne are described as 8-jointed.* The genus Orchesella (Pl. LV, fig. 9) has long, 6-jointed antennz ; the basal and third segments are short; the second and fourth, always counting from the base, are longer; the two apical, again, about equal to one another, and together almost as long as the four basal segments. All the other genera of Popuripm have the antenne 4-jomted. In Tomocerus the two basal segments are short, the third is elongated, in some cases very much so, and, as is also the short terminal segment, 1s divided into a great number of subsegments. 1. dongicornis often rolls up its antenne spirally. It is remarkable that in full- erown specimens of this species the terminal segment is very generally wanting. M. Bourlet, indeed, describes it as having only three segments to the antenne, and though [ have met with perfect speci- mens, still, since this work has been in preparation, though I have examined hundreds of specimens, 1 Bourlet, ‘Mém. Soc. Douai,’ 1842, p. 56. ANTENNA. 59 I have been unable to find one which was _ perfect in this respect. In Templetonia the apical segment is the longest and is ringed, while the third, on the contrary, is simple. The genera Achorutes and Podura, as well as the species belonging to the two small families Lipurtip# and Awnovuripé, all have the antennz quite short, simple, and 4-jointed. In ‘his original description of Jsotoma stagnorwm (Podura aquatica cinerea) De Geer’ remarked with surprise that the antennz were not always symmetrical, but that, while four was the normal number of seg- ments, many specimens had one antenna with four, as usual, the other with only three. The individual which he figured was in this condition. Latreille, also, in his ‘Organisation extérieure et comparée des Insectes de ?Ordre des Thysanoures,”’ observes that the antenne of the Poduride “sont sujets a des monstruosités, puisque je possede un individu ot l’une des antennes a trois articles, et Pautre deux. Je les al examinées, l’animal étant vivant, et je n’al apergu aucune trace de mutilation. Les variations ainsi que les anomalies relatives au nombre des yeux lisses semblent indiquer que la nature tatonne ici, en quelque sorte, et qwil ne faut pas dés-lors attacher une grande importance a ces caractéres numériques.”’ M. l Abbé Bourlet gave as a character of his genus Heterotoma (a name which he subsequently changed for Aitheocerus), which is composed principally, but not entirely, of the species forming Templeton’s genus Orchesella, that the segments of the antennze varied from 2 to 5, those even of the same individual being often dissimilar in the number of their segments. He was aware that M. Macquart regarded these differ- ences as either abnormal or accidental; but he rejected this explanation because—“ 1°. Dans le cas ou les antennes sont inégales, le dernier article de la 1 « Act. Soc. Reg. Sci. Upsal.,’ 1740, p. 64. 2 “Nouv. Ann. du Museum,’ v. i, p. 186. 60 ANTENNA. plus courte, quel que soit son rang numérique, n’est jamais conforme a l’article correspondant de Vautre antenne; 2°. il affecte constamment une forme ana- logue a celle de larticle terminal, ou le cinquiéme ; 3°. ilen est de méme pour les antennes égales, mais ayant moins de cinq articles; dans ce cas, le dernier est toujours plus gros et plus long que le terminal de Vantenne normale, quoique ayant une forme analogue et la méme couleur; 4°. on n’apercoit a l’extrémité de Varticle aucune trace de fracture ; 5°. plusieurs jeunes Podurides et un grand nombre d’adultes ont été trouvées ainsi conformées; le nombre de celles-ci était, a Pegard des