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CHALLENGER DATOS NGG 2 a HOES YaRPAURSS 31/87/3576 UNDER THE COMMAND OF Cserain) GEORGES NAR ES RIN. bakes: Captain FRANK TOURLE THOMSON, R.N. PREPARED UNDER THE SUPERINTENDENCE OF THE LATE Sallie ie Vel LaLsE OU S OiNge Kens, PARAS. ee cuce REGIUS PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF EDINBURGH DIRECTOR OF THE CIVILIAN SCIENTIFIC STAFF ON BOARD AND NOW OF IPOMEIINGY MEU RORCACY ait RU SSE: ONE OF THE NATURALISTS OF THE EXPEDITION ZOOLOGY IW Oe Vi PART XIX.—REPORT ON THE PELAGIC HEMIPTERA., Published by Order of Wer Majestp’s Government tian PRINTED FOR HER MAJESTY’S STATIONERY OFFICE AND SOLD BY LONDON :—LONGMANS & CO.; JOHN MURRAY; MACMILLAN & CO.; SIMPKIN, MARSHALL & CO, TRUBNER & CO.; E. STANFORD; J. D. POTTER; anD KEGAN PAUL, TRENCH, & CO. EDINBURGH :—ADAM & CHARLES BLACK anp DOUGLAS & FOULIS. DUBLIN :—A. THOM & CO. anpD HODGES, FIGGIS, & CO. 1883 Price Three Shillings and Sixpence. PRINTED BY NEILL AND COMPANY, EDINBURGH, FOR HER MAJESTY’S STATIONERY OFFICE. \ ar ih Nahe IN ORS Tue special work of the Challenger Expedition was the examination of the Physical and Biological conditions of the great Ocean Basins, and the detailed Official Reports ov the Scientific Results of the Expedition will—with few exceptions—be limited to those departments of research referring more or less directly to the Ocean. The large collections of Insects, Land Shells, Spiders. Amphibians, Reptiles, and Mammals, made by the Naturalists on land at the various ports and islands touched at throughout the cruise, being regarded as “Incidental Collections,” have been deposited in the British Museum, to be examined by the officers in charge of the national collections. These “Incidental Collections” will be referred to in the Volumes devoted to the Narrative of the cruise, but it is not proposed to publish any detailed Reports concerning them. The only Insects having a truly oceanic habitat belong to the genus Halobates and one or two allied genera, and consequently this Memoir, by Dr. F. Buchanan White, on those Pelagic Hemiptera, is the only one relating to the class Insecta which will appear in the series of Challenger Reports. The Memoir was received on the 6th February 1883, and forms Part. XIX. of the Zoological Series of Reports on the Scientific Results of the Expedition. Joun Murray. CHALLENGER OFFICE, EpinpurcH, 20th July 1883. iso “ a £ yh es ge -t ace oda el a) poly > caf grt THE VOYAGE OF H.M.S.. CHALLENGER. ZOOLOGY. REPORT on the Peracic Hemirera procured during the Voyage of H.MLS. Challenger, in the years 1873-1876 By Fi Bucuanan Wuire, M.D., F.LS. | I. HISTORY AND BIBLIOGRAPHY. THE only Pelagic Hemiptera, and indeed the only truly pelagic insects, belong to the venus Halobates and one or two allied genera. Halobates was founded in 1822 by Pro- fessor J. Friedrich Eschscholtz, of the University of Dorpat, for the reception of three species taken during von Kotzebue’s voyage round the world in the ship “ Rurick.” Since that time a few other species have been described, but specimens are still rare in collections, and consequently little has been added to our knowledge of the genus. A special interest is attached to these animals, as being the only pelagic representa- tives of their class. It is true that a few other insects are marine,’ but they are all found in close proximity to the shore, whereas the species of HZalobates usually, and in some cases only, occur at a considerable distance from any land. Moreover, their struc- ture would seem to indicate that they are archaic forms of very great antiquity, and hence all that can be learned with regard to them is of very great importance. Abundantly as they seem to be distributed in the tropical seas, specimens are very rare in collections, and, when named at all, are in most cases wrongly determined. For these reasons it has been deemed advisable to attempt a monograph of the genus, though it is probable that many species yet remain to be discovered by those who have the opportunity and the will to turn their attention in this direction. The literature of the genus is not extensive, but, as it is much scattered, it has been 1 Amongst these may be noticed species of Aépus, Hesperophilus, Micralymna, &c., belonging to the Coleoptera; Aépophilus amongst the Hemiptera; two Caddis-flies (Philanisus plebejus and Molanna, sp.) amongst the Neuroptera; and a few Diptera (such as Chironomus oceanicus); which either in the perfect or in the larval condition habitually live below high-water mark. In addition to these some other species are to be found occasionally in salt or brackish water. (ZOOL. CHALL. EXP.—PART XIx.—1883.) dt al 2; THE VOYAGE OF H.M.S. CHALLENGER. thought desirable to reproduce in this monograph the more important parts of it, in order that those who wish to study the species in their native localities may have every facility for so doing. Moreover, since the types of several of the described species have apparently disappeared, it is desirable that the student should have, in an easily accessible form, the exact words of those who have written on the subject. We will therefore begin by reproducing, in chronological order, the more important writings on the subject. l.—J. Frrepricn EscuscHourz. Entomographien. Erste Lieferung, 1822, p. 106, Taf. il. figs. 3, 4, and 5. Also Naturwissen- schaftlich. Abhandl. aus Dorpat, 1823, p. 163, Taf. ii. figs. 3, 4, and 5. “78a. Halobates. “Diese neue Wanzengattung aus der Familie Cimicides Ploteres Latr. ist mit Velia und Gerris Latr. sehr nahe verwandt und hat sich den Ocean zum Jagdrevler erwithlt ; man kann sie so bezeichnen : “ Antennee articulo basali elongato. Rostrum breve, conicum, vagina triarticulata. Collare annuliforme. Thorax maximus, apterus. ‘Tarsi antici triarticulati : articulo secundo ultra tertium unguiculatum protenso ; posteriores biarti- culati, exunguiculati. “ Der Kopf ist vorgestreckt, breit. Augen gross; Nebenaugen fehlen. Kopfschild vorgestreckt, gewolbt. Oberlippe eiformig, gekriimmt, spitz. Riisselscheide dreighedrig ; das erste Glied kurz breit, das zweite das liingste, und das Endglied gekriimmt und spitz. Borsten drei. Fiihler vor den Augen auf einer starken Erhéhung des Kopfs sitzend, vierghedrig, fadenformig ; das erste Glied das liingste. “ Halsschild sehr kurz, ringformig. Mittelleib sehr gross, ungefliigelt. Hinterleib sehr kurz. Afterdecke des Miinnchens spitz; des Weibchens gross breit rautenformig. Vorderbeine kurz mit dicken Schenkeln ; Schienen von gleicher Liinge mit letztern, walzenformig, am Ende mit einem nach innen vorspringenden hakenférmigen Fortsatze, der in eine Furche zwischen Beinwurzel und Schenkel passt ; die Fiisse dieser Beine scheinen, von oben betrachtet, nur aus zwei ziemlich langen dicken Gliedern zu bestehen ; aber an der Unterseite des zweiten liingern Gliedes bemerkt man noch ein drittes sehr kurzes abstehendes Glied, das am Ende mit zwei gekritimmten Haken bewaftnet ist. “Mittlere Beine zwei bis dreimal linger als der Kérper, dem Mittelleibe an seinem untern und hintersten Theile angefiiet ; Hiiftelied sehr dick, kurz; Gelenkkopf lang und mit seinem zugespitzten Ende dem Schenkel von der Seite angeheftet ; Schenkel sehr lang, walzenformig ; Schienen diinner und um mehr als die Hiilfte kiirzen. Fiisse zweighedrig ; das erste wenig kitrzer, als die Schienen und gewoéhnlich gekriimmt ; das Endghed kurz, fein und am Ende mit einigen langen Haaren bewaffnet. REPORT ON THE PELAGIC HEMIPTERA. 3 “ Hinterbeine tiber den mittlern eingefiigte, um ein Drittheil kiirzer als diese, mit lingern Hiiftgliedern, feinern Schienen und Fussgliedern, von welchen letztern das erste Glied kaum linger als das zweite zugespitzte und langebehaart ist. “Der K6rper ist mit sehr feinen silberfarbenen Schuppen bedeckt, die Beine gewohnlich schwarz. Die Thierchen springen auf der Oberfliiche des Meeres herum, und kommen nur in den Tropen oder in der Niihe derselben vor. Drei mir bekannt gewordene Arten unterscheiden sich folgendermassen : “78. b. Halobates micans (Taf. ii. fig. 3). “H. corpore conico, subtus argenteo, supra cinereo eneo micante ; oculis atris. ‘Tm siidlichen stillen Meere und im siidlichen atlantischen Meere. “Linge 15 Linien, grésste Breite eme Linie. Kopf breiter wie lang, gewolbt, der ordsste Theil erau, der vordere Rand silberweiss. Augen zur Seite des Kopfs hervorstehend, gross, schwarz. Fiihler etwas liinger als der halbe Korper, am Ende etwas verdickt, Glieder walzenformig, schwarz, matt; das erste so lang, als die tibrigen zusammengenommen, die beiden folgenden gleich lang, das letzte etwas linger als das vorhergehende. “ Halsschild breiter als der Kopf (ohne Augen), mehr als dreimal breiter als lang, vorn stark und hinten kaum merklich ausgeschnitten, Seiten gerade, hinabhiingend, Oberfliche kaum gewolbt mit zwei liinglichen Eindriicken am Vorderrande ; grau etwas gliinzend. Mittelleib vorn etwas breiter, als das Halsschild, bis hinter der Mitte ziemlich stark erweitert, dann gleich breit, fast zweimal so lang als Kopf und Halsschild zusammen, vorn gewolbt, hinten ausgehéhlt abschiissig, mit einer kleinen etwas unbestimmten mittlern Liingskante am letztern Orte ; schwiirzlich grau mit Messingelanz. Hinterleibsringe weissgrau. Unterseite des ganzen Kérpers silberweiss. Beine schwarz, Vorderschenkel bliulich an der Innenseite weiss behaart ; so auch die Vorderschienen. “Teh sah von dieser Art nur einige Miinnchen. “79, Halobates sericeus (Taf. 11. fig. 4). “H. corpore ovali, subtus argenteo, supra albo cinereo ; oculis flavis. “Tm nordlichen stillen Meere in der Niihe des Aequators. “TLiinge 14, Breite 3 Linien, Kérper linglich. Kopf etwas grisser und starker gewolbt, als beim vorigen ; mit zwei kleinen Punkten, weissgrau. Augen gelbbraun. Fiihler wie beim vorigen; so auch das Halsschild, nur sind hier die Quereindriicke stiirker. Mittelleib vorn deutlich breiter, als das Halsschild, anderthalbmal so lang als Kopf und Halsschild zusammen, in der Mitte ein wenig erweitert, Oberfliche vorn schwach gewélbt, hinten flach, weissgrau, ohne Glanz; Hinterleibsriicken von derselben Farbe. Kérper unten silberweiss, flach. Vorderbeine grau, hintere Beine schwarz. “ Von dieser sehr hiiufigen Art sind mir beide Geschlechter vorgekommen. 4 THE VOYAGE OF H.M.S. CHALLENGER. “80. Halobates flaviventris (Taf. ii. fig. 5). ‘“‘H. corpore cylindrico, subtus argenteo, supra albo ; abdomine maculisque pectoris apice flavis. “Tm siidlichen atlantischen Meere. “Linge 2 Linien, Breite $ Linien. Kopf stark gewolbt, weiss, im Riicken eine gelbliche erhabene Linie. Fiihler fast so lang als der Mittelleib, schwarz; das erste Glied viel linger als die tibrigen etwas dickern, das zweite etwas linger als jedes der beiden letztern unter sich gleich langen Glieder. Augen bei emem Exemplare ganz schwarz, beim andern gelb. “ Halsschild drittehalbmal so breit als lang, weiss, mit zwei eingedriickten Punkten. Mittelleib vorn viel breiter als das Halsschild, lang, in der Mitte kaum breiter als an beiden Enden, vorn gewolbt, hinten platt mit zwei eingedriickten Punkten. K6rper unten silberweiss ; der Bauch und ein grosser Fleck auf dem hervorragenden Theile der Brust, welcher die mittlern Beine triigt, gelb. Vorderbeine im Verhiiltniss zu den iibrigen Arten lang, schwarzgrau ; die tibrigen Beine sehr lang und fein, schwarz. “Tech sah nur zwei Weibchen. Ein Halobates, der sich im Brittischen Museum befindet, ist in der Niihe des Ausflusses des Congostroms gefangen worden; zu welcher Art er aber gehore, ist mir nicht bekannt.” [Though the description of the genus is erroneous in several important particulars (the rostrum is four and not three-jointed, the front tarsus is two and not three-jomted, and the hind tarsus is one-jointed, and has, as well as the middle tarsus, claws), it must be remembered that appliances for the examination of the smaller parts of insects were not so perfect in 1822 as they are now, and that Eschscholtz’s descriptions are on the whole much more correct than some subsequent writers have imagined. It is to be noted that he confounded the sexes, a mistake in which he has been followed by almost all his successors.—F. B. W. | IJ.—F. L. pre Laporte, Comte de Castelnau. Essai Vune Classification Systématique de l’ordre des Hémipteres. Guérin-Méneville’s Magasin de Zoologie, p. 24, 1833. “Genre 4. Halobates, Esch. “ Antenne sat breves, articulis 4, post primum fractee ; 1° caeteros und longitudine zequante ; 3° preecedenti breviore; ultimo cylindrico, subovato.—Rostrum brevissimum validum.—Tarsi elongati, articulis vix conspicuis; antici haud unguiculati—Corpus brevissimum, convexum; abdominis articulis vix conspicuis, imbricatis,—Pedes postici supra intermedios inserti. “Téte large, yeux assez saillant; corselet grand, presque carré, alongé, coupé carrément en arriere; pas d’écusson; abdomen ne formant pas la sixieme partie de la REPORT ON THE PELAGIC HEMIPTERA. 5) longeur du corselet ; pattes antérieures courtes, les autres tres longues ; base des cuisses postérieures placées au-dessus des intermédiaires. “Ces insectes habitent parmi les plantes marines des mers de l’océan Indien. ‘« Halobates micans, Escholtz., Entom., 1822, p. 106, No. 78. “Ajoutez : H. flaviventris et H. sericeus du méme, et une nouvelle espece que nous possédons et qui vient des mers de la Nowvelle- Guinée.” [The author figures in outline H. flaviventris, Esch., and gives enlarged drawings of an antenna and front leg. Notwithstanding his remark “haud unguiculati,” the front tarsus is represented with two claws. The hind tarsus is represented as two-jointed, Whatever species the drawing was taken from, it certainly does not represent H. flavi- ventris, Esch.—F. B. W. ] I1].—Dr. Hermann Burmeisrer. Handbuch der Entomologie. Zweiter Band, p. 208, 1835. “J. (92.) Gatt. Halobates, Esch., Lap.’ “Fihler viergliedrig, das erste Glied so lang als das zweite und dritte zusammen, beide von gleicher Liinge, das vierte etwas liinger und dicker. Augen vorragend, keine Nebenaugen. Mittelbrustring sehr gross, stark nach hinten verliingert, so dass die Gelenkgruben der Mittelbeine unter denen der hinteren stehen. Fliigel fehlen. Beine ungleich, die vorderen kurz mit verdickten Schenkel, aufrechtstehend ; Fiisse zweigliedrig, Krallen in einen Ausschnitt an der Unterseite in der Mitte des zweiten Gliedes befestigt, klein. Die vier hinteren Beine, besonders die mittleren, stark verlingert, fein, verjiingt ; Fussglieder ungleich, das erste 6 mal so lang als das zweite, an den hintersten Beinen fast gleich lang, gewimpert. Hinterleib iiusserst klein, kegelfOrmig, eng an den Brust- kasten angezogen, “Die Arten leben auf der Oberfliiche des Meeres zwischen den Tropen ; drei wurden zuerst von Herrn Eschscholz auf Kotzebue’s erster Reise um die Welt entdeckt, andere an der Kiiste von Mexico und Brasilien gefangene befinden sich im Konigl. Museum. “1. H. micans.—Corpore conico, subtus argenteo, supra cimereo, aeneo-micante ; oculis atris. Long. 13./” “ Esch., Entomogr. (In den Naturwissenschaftlich. Abhandl. aus Dorpat, 1823. 8.) p. 163. 78. 6. tab. 2. fig. 3. “ Auf dem siidlichen stillen Meere und dem siidlichen atlantischen Meere. “1 Wie leichtfertig Herrn Laporte’s Untersuchungen zum Theil sind, davon liefert Nichts einen besseren Beweis, als wenn mann seine Charakteristik dieser Gattung mit der Natur vergleicht.” 6 THE VOYAGE OF H.M.S. CHALLENGER. “9. H. sericeus.—Corpore ovali, subtus argenteo, supra albo-cinereo ; oculis flavis. ws Long. 13”. “Esch. ebenda p. 164. 79. tab. 2. fig. 4. « Ziemlich hiiufig auf dem nordlichen stillen Meere in der Nahe des Aequators. Laport. Hém., pp. 24. 4. “3. H. flaviventris.—Corpore cylindrico, subtus argenteo, supra albo; abdomine maculisque duabus pectoris apicalibus flavis. “Esch, ebenda 165. 80. tab. 2. fig. 5. _ “Auf dem siidlichen atlantischen Ozean.” [Dr. Burmeister follows Eschscholtz in ascribing two joints to the hind tarsus. He is also mistaken in thinking that the relative lengths given by him of the joints of the middle tarsus are generic characters. They, in fact, differ in the various species. —F. B. W. | IV.—Rosert Tempueton, R.A. Description of a new Hemipterous Insect from the Atlantic Ocean. Transactivns of the Ento- mological Society of London, vol. i. p. 230, 1836. “ HyDROMETRID&, Leach. “Genus Gerris, Latr. “Sub-genus Halobates, Eschscholtz (Entomographien). “Sp. H. Streatfieldana, pl. xxi. fig. A. “Broadly ovate, or lozenge-shaped, brilliant black ; eyes, two minute spots near the prothorax, and the sides and apices of the first uncovered pair of abdominal annuli (4th and 5th) rufous; beneath brownish-black, the first five abdominal rings yellowish with rufous apices, offering the appearance of five narrow transverse fasciz ; last rings broad and rufous black. Apterous. “Leneth, 0°13 inch. “Found on the Atlantic Ocean, in longitude 20° under the line. “This beautiful species was captured nearly midway between the continents of Africa and America, by Colonel Streatfield, 87th R.T.F., whose name I have in conse- quence done myself the favour to affix to it, as being most appropriate, and as a slight testimony of the grateful recollection I have of his kindness in presenting me with many interesting species of insects and other rarities. The sea was quite smooth, with a gentle swell, at the time the insect was caught; a number were swimming about among the Porpite, which formed the first object of attraction, and fortunately directed attention to the insect. The singularity of its distance from any land, and the possibility of its being driven off from the African coast by the south-eastern gales, gave full play to conjecture, and excited our attention to the little creatures in the water, in the hope of ascertaining on what objects it preyed; but all possibility of.discovering this was quickly put a period REPORT ON THE PELAGIC HEMIPTERA. if to by the S.E. trade sweeping over the surface and banishing all traces of the Medusi and their companions. “This species obviously belongs to a section or sub-genus distinct from that in which our linear European species are placed, and characterised by the contracted dimensions of the body, and the dilatation of the head and prothorax and the shortness of the latter. When examined minutely we find the whole body covered with minute hairs, those on the legs predominating beneath, the upper curving downwards. ‘The head is somewhat triangular, with two cupped processes laterally, within which lie the bases of the antenne ; two small rufous macule are on the sides of the middle lme closely adjoming the prothorax. The eyes are large, rufous, semi-globular, and occupy the space between the base of the head and the processes of the antennz, emarginating the corselet laterally. The antenne are about two-thirds the entire length of the body; the first joint slender and curved outwards, the last thickest, attenuating towards the tip. “The prothorax is excessively short, collar-like, and gently channeled above into three sub-equal divisions, which nearly disappear in the dried specimen. The first pair of legs, arising closely to the mesothorax beneath, are moderately long, rather robust ; the coxa short, obconic, and curved ; the femur slightly /-shaped, with four or five strong black spines near its base exteriorly ; tibia basally attenuated, arising with a curve from the preceding joint and with four or five strong black spines inferiorly, apically giving origin to a strong obtuse process, which projects backwards and outwards from near the articu- lation. Tarsus with the two joints sub-equal, the last diminishing im diameter beyond its middle, after giving attachment to two strong claws and an anomalous horny process on the under side, and also furnished with two long curved spines arising from the back part on each side, and lying adpressed among the hairs. “The metathorax and mesothorax seem confounded together, presenting superiorly an hexagonal figure, a little longer than broad, the anterior side being carried a little forwards, so as to leave the lateral angles behind the centre. The posterior surface is transversely striate from being impressed upon the abdominal rings. The sides in the dried specimen become somewhat hoary from the light thrown back by the minute hairs. Beneath it is somewhat similar in form, but excavated behind, exposing in the sinus the abdominal rings. The sides posteriorly are rugose, with trochantines, from whence proceed directly backwards the cox of the last four legs, that of the posterior pair lying beneath the other on each side. The legs are slender, the middle pair exceeding the first, and the last pair the middle, by about one-third.* The last also has the apical half of the tibia, and first joint of the tarsus, with a row of long hairs beneath. Above the origins of the legs we find rudimentary processes, which as the insect is apterous, must be looked upon as those of the undeveloped wing.” [This species has apparently not been taken again.—F. B. W. | 1 The middle legs here described are really the hind legs.—F. B. W. 8 THE VOYAGE OF H.M.S. CHALLENGER. V.—Le Maraquis Maximinien SpPrnoua. Essai sur les Hémiptéres Hétéroptéres, p. 64, 1837. “11 n’est pas encore démontré que les Halobates connus soient des insectes parfaits. Les derniers anneaux de l'abdomen ne paraissent pas étre entierement développés, et si les observations du Comte Alphonse Castiglioni sur les métamorphoses de la Ploiaria domestica Scop. méritent notre confiance, comme je le crois, l’exemple de cette larve qui sort de l’ceuf avec un simple rudiment d’abdomen confirmerait nos doutes relativement aux Halobates. “ Rx. Halobates sericeus, Esch. “1 Hydrometra abbreviata, Fab. ne serait-elle pas un Halobates et est-elle réellement des Pyrénées ?” {According to Stal, Fabricius described the larva of Limnotrechus lateralis or of Limnotrechus asper under the name Hydrometra abbreviata.—F. B. W. | , VI.-—Professor EMILE BLANCHARD. Histoire Naturelle des Insectes. t. ii. p. 98, 1840. “ Halobates, Esch., Lap. “Ce genre ala plus grand analogie avec celui des Gerris, il n’en differe réellement que par la forme ramassée du corps, et surtout de abdomen, dont les segments sont tres- courts et relevés ; les antennes aussi sont beaucoup plus courtes, leurs pattes n’atteignent un aussi grand développement et les organes du vol manquent totalement. “Les Halobates courent sur les eaux de la mer pres des cétes; on n’en a jamais rencontrés pourvus d’élytres et d’ailes: ce qui, joint a la forme rabougrie de leur corps, a fait présumer que ces insectes n’avoient pas atteint leur entier développement et quils pourroient bien étre de veritables Gerris a état de larve. ““schscholtz en a fait connaitre plusieurs especes dans son Entomographie. “1. Halobates micans. “Esch., Ent., p. 163, n. 78, tab. 2. fig. 3.—Burm., Handb. der Ent., t. ii. p. 208, n. 1. “Long. 2 lig.—Corps cdnique, grisitre en dessus, chatoyant le bronzé, entierement dun blanc argenté en dessous ; yeux noires ; pattes grisdtres, couvertes de duvet argenté comme les autres parties du corps. “Cette espece vit dans l’Océan-Atlantique. REPORT ON THE PELAGIC HEMIPTERA, 9 “9. Halobates sericeus. “Esch., Ent., p. 164, n. 79, tab. 2. fig. 4.—Lap., Hémipt., p. 24, n. 4.—Burm., Handb. der Ent., t. ii. p. 209, n. 2. “Long. 1 lig. $.—Cette espéce se distingue de la précédente par son corps plus ovalaire et dune moindre taille, par ses yeux d'un jaune pile et le duvet qui recouvre le corps Vun gris-blanchatre. Cette espece se trouve dans les mers équatoriales.” VII.—C. J. B. Amyor and AUDINET SERVILLE. Histoire Naturelle des Insectes. Hémipteres, p. 411, 1843. “Genre 335.—Halobate. Halobates, Esch. Lap.—Burm.—Blanch. “ Téte triangulaire, avee un prolongement court et mousse entre les antennes.— Yeux eros, globuleux, saillants, débordants un peu les cétés du prothorax.—Ocelles nuls.—- Antennes de quatre articles cylindriques ; le second un peu plus court que le premier ; le troisieme un peu plus long que le premier et que le dernier (dans les larves, le premier est aussi long que tous les autres pris ensembles; le second & peine plus long que le troisieme) ; le quatritme un peu épaissi et & peine plus long que le second.—Bec trées- court, gros & la base et pointu au bout (dans les larves, les deux premiers articles, qui semblent n’en former qu’un seul, sont courts, annuliformes ; le troisieme le plus long, le quatrieme court).—Prothorax en losange aux quatre cOtés & peu pres égaux, s’étendant postérieurement & angle aigu et couvrant entitrement le mésothorax (trés-court dans les larves, avee le mésothorax trés-grand, formant la majeure partie du corps, et point d’écusson).—Elytres un peu plus longues que l’abdomen, assez amples, offrant deux cellules basilaires allongées et trois discoidales & la suite ; ailes un peu plus courtes que les élytres (les élytres et les ailes manquant, suivant tous les auteurs qui n’ont vu que les larves).—Abdomen conique, & peu pres aussi long que le reste du corps (trés-petit, presque non apparent en dessus dans les larves, tous les segments pouvant néanmoins étre comptés sous le ventre et les organes sexuels assez développés).—Pattes antérieures courtes ; cuisses un peu épaissies; jambes avant une dent Vextrémitié ; tarses de deux articles & peu pres d’égale longeur, cylindriques ; crochets insérés dans une échancrure au milieu du deuxiéme article; pattes intermédiaires tres-longues, filiformes, msérées tres- loin des pattes antérieures 4 cause de la grandeur du mésosternum, les postérieures trés- fines, plus courtes que les intermédiaires, tres-prés des quelles elles sont insérées ; cuisses intermédiaires plus longues que les jambes; les quatre derniers tarses de deux articles cylindriques, frangés, dont le premier six fois plus long que le second dans les tarses intermédiaires, tous deux presque d?gale longeur dans les tarses postericures ; crochets ne nous paraissant pas exister ? (ZOOL, CHALL. EXP,—PART X1x.—1883.) ee 10 THE VOYAGE OF H.M.S. CHALLENGER. “Du grec adws? aire, et Baww, marcher. “On avait soupconné déja que les individus sur lesquels ce genre avait été établi, n’étaient que des larves; nous en avons la preuve aujourd’hui, d’apres l'espece ailée que nous décrivons ci-apres. Mais un fait qui n’avait jamais été relevé, c'est que De Géer parait evidemment avoir décrit et figuré (Mém. HI. 320, 321, 322; et pl. 16, fig. 16, 17, 18, et 19) des larves et une nymphe de ce genre, observées par lui en Suéde, quoique toutes les especes existant maintenant dans les collections viennent des tropiques, ot on les trouve 3 la surface des mers. Cet auteur tombant en cela, ce nous semble, dans la plus étrange erreur, n’a voulu les considérer que comme Jes petits dune espece de Gerris, et cependant il a décrit et figuré la nymphe elle-méme avec ses moignons dailes et l'abdomen aussi court que dans la larve, quand il décrivait et figurait plus haut la larve de cette espece de Gerris avec l’abdomen aussi développé que dans Vinsecte parfait, dot résultait la preuve que l’abdomen conservait toujours la méme proportion relative dans les différ- entes périodes de développement de l’insecte, et que par conséquent il ’y avait la deux especes différentes. Latreille (Nouv. dict. hist. nat. [1803] IX. 415) rapporté toutes les observations de De Géer & ce sujet, en se laissant abuser lui-méme par l’auteur, et continuant 4 prendre les uns pour les petits des autres ;' mais ce qu'il y a de singuler, est quil ait dit ensuite (/oc. cit., 416) que Pespéce & laquelle appartenaient ces petits d abdomen avorté, etait des Indes-Orientales, quand il avait dit une page plus haut (7d. 414) que De Géer avait observé en Suéde les trois especes dont il parlait. “1. H. albinerve. Halobates albinervus.” [This fresh-water species has been removed to the genus Brachymetra, Mayr, and therefore need not be further considered here, beyond calling attention to the fact that of course the generic characters of Halobates, Esch., are not the same as those of Halobates, Amyot et Serv.—F. B. W.] “9. H. soyeux. Halobates sericeus, Esch. “Entomogr., Zrans. des Sciences nat. de Dorpat. 1823. 3, p. 164. 79. tab. 2. fig. 4—Burm., Ent. ii. 209. 2.—Blanch., Hist. nat. ins. i. 98. 2. “(Long., 9,004). Larve. Corps ovulaire, d’un soyeux blanchatre en dessous, d'un cendré grisitre en dessus. Male et femelle. ce 1 ‘ap de Bonne-Espérance. M. Burmeister dit: Du nord de la mer Tranquille, pres de ! Equateur.” 1 The authors remark in the errata (p. 648), “ Au lieu des cing lignes qui suivant et ol nous avons mal interprété la pensée de Latreille il faut lire ce qui suit: Il avait bien distingué toutefois trois especes dans les individus deécrits et figurés par De Géer, la troisitme étant celle dont la larve et la nymph avaient l’abdomen tronqué; mais il s‘est trompé en attribuant 4 cette espéce la synonymie du Gerris paludum, Fabr., dont la larve et la nymphe ont labdomen aussi développé que Vinsecte parfait.” REPORT ON THE PELAGIC HEMIPTERA. 11 VIIL—Dr. G. A. W. Herricu-ScuarFer. Die wanzenartigen Insecten. Band viii., p. 108, tab. eelxxxvi., 1848, “Genus Halobates, Esch. “ Kine ganz eigenthiimliche Form ; eiformig, mit grossem Kopfe, grossen vorstehenden Augen, kurzem Thorax, vorstehenden Schultern, ohne Spur von Fliigeldecken und Fliigeln, langen Beinen, deren vorderste die dicksten und kiirzesten, deren vier hintere weit hinter der Mitte des K6rpers eingefiigt, seitlich ausserordentlich von einander ent- fernt sind und deren Gleder sich endwiirts haarformig verdiinnen. Die Mittelbrust ist ungemein gross und reicht weit hinter die Mitte des Kérpers. Der Hinterleib ist iusserst klein, conisch, beim Weibe mit eckigem Anhange. “ Schnabelscheide bis zur Mitte der Hinterbrust reichend, dreiglederig, das mittlere Glied am lingsten ; Fihler von mehr als halber Korperliinge, fadenformig, Viergliedrig, das erste Glied am liingsten. Nebenaugen kann ich nicht entdecken. Der Prothorax ringformig, unten mit breiter, seichter, nicht scharf begrenzter Liingsrinne ; die Vorder- beine entspringen am Hinterrande der Vorderbrust, nahe beisammen. Die Mittelbrust nimmt mehr als die halbe Korperliinge ein, die Mittelbeine sind an ihren hinteren seit- lichen Ecken in ungeheuerer Entfernung von einander eingefiigt. Die Hinterbrust ist ganz von der Mittelbrust verdeckt und steht nur jederseits an der oberen Korperfliche als Lappen vor, so dass die Hinterbeine kaum etwas weiter nach riickwiirts eingefiigt sind als die Mittelbeine, aber etwas héher. Keine Spur von Einfiigungsstellen der Fliigel oder Decken.—An den Vorderbeinen alle Glieder ziemlich gleich dick, also fadenformig ; Hiiften kurz, Schenkel etwas liinger als die Schienen; Fuss kiirzer, zweighiedrig, das erste Glied kiirzer. Die vier Hinterbeine borstenférmig, die mittlern liinger ; die Glieder der Fiisse kann ich nicht genau unterscheiden ; es scheimen deren zwei, das zweite viel kiirzer. “Die Arten leben auf der Oberfliiche des Meeres zwischen den Tropen, wahrscheinlich gesellschaftlich ; Burmeister kennt mehrere Arten. “T. Vorderschienen am Ende erweitert, Vorderfuss mit zwei Krallen in einem Ausschnitte der Mitte des Endgliedes, Schenkel aller Beine linger als ihre Schienen. Die Hintertarsen (nur des Mannes?) lang borstig, Korperfliche grau, durch feine Behaarung seidegliinzend.” “Tab. cclxxxvi. fig. 880 mas, 881 foem. “ Halobates sericeus, Esch. “ Cinereus, oculis subferrugineis. “ Eschscholtz, Entomographien, 1822, t. 2. fig. 4. * Asehorau, die Augen braungelb. 12 THE VOYAGE OF H.M.S. CHALLENGER. “ Beide Geschlechter von Herrn Sturm, welcher sie aus der Siidsee von Herrn Eschscholtz erhielt. ‘Folgende Arten sind mir unbekannt : « HT, micans, Esch., Entom., t. 2. f. 3—Burm., p. 209. * Cinereus oculis atris. “ Ascherau, die Augen schwarz. “ Aus dem siidlichen stillen und atlantischen Meere. Herr Eschscholtz sah nur einige Minnchen. . “ HT, flaviventris, Esch., Entomogr., t. 2. fig. 5.—Burm., p. 290. “ Cinereus oculis atris, abdomine et pectoris apice flavescentibus. — “ Vielleicht das andere Geschlecht zu voriger, aus dem siidlichen atlantischen Ocean ; Herr Eschscholtz sah nur zwei Weibchen.” II. Vorderschienen ohne Erweiterung, Vorderfuss ohne Krallen ; Schenkel der Mittel- beine kiirzer als ihre Schienen, Schenkel der Hinterbeine lang borstig ; Korper glatt, fleckig.” [In this section is placed Halobates pictus, Germ., which, being a fresh-water and not a marine species, and being moreover nota true Halobates, need not be further considered. In the generic description some of Eschscholtz’ mistakes are repeated—F. B. W. | IX.—Lfton FAmrMaIrre. > Annales de la Société Entomologique de France. Bulletin Entomologique. Année 1848. Deuxitme Trimestre, p. Xxvi. “M. Amyot, dans son Histoire Naturelle des Hémipteres, p. 412, dit: ‘On avait déji soupeonné que les individus sur lesquels ce genre avait été établi n’etaient que des larves, nous en avons la preuve aujourd’hui d’aprés Vespece ailée que nous d’ecrivons ci-apres.’ “MM. Burmeister et Spinola, sans étre aussi affirmatifs, croient aussi qu’on ne connait encore que les larves des Halobates. Il n’y a que le fondateur du genre, Eschscholtz, et M. E. Blanchard, qui n’expriment aucun doute sur létat parfait de ces insectes. Je crois étre X} méme de résoudre cette question en détruisant largument apporté par M. Amyot, et en apportant des preuves directes & l'appui de mon opinion. “M. Amyot decrit sous le nom d’ HZ. albinervus un insecte tres voisin des Gerris, ailé et provenant de capitainerie de Goyaz; or, cette province, située entre des montagnes, est & 200 lieues de la mer, ce qui exclut toute idée d’insecte maritime et explique pour- quoi auteur ne veut pas admettre les Halobates tels quils ont été decrits par Eschscholtz. “ Notre collegue M. Ch. Coquerel, & qui nous devons des observations intéressantes REPORT ON THE PELAGIC HEMIPTERA. 13 e sur lentomologie de Madagascar, a rapporté des mers qui avoisinent cette ile une certain nombre de véritables Halobates apteres, de tout age, de tout sexe et de deux espéces, parfaitement conservés dans de l’esprit de vin. Parmi eux se trouvaient deux énormes femelles, au ventre rebondi, qui au premier coup d’ceil, me parurent porter dans leur flancs la solution de la question. En effet, avec Yaide du scalpel, je fis sortir de l’abdo- men 15 ou 20 corps oblongs, assez gros, d’un jaune soyeux pale, qui envahissaient méme une portion du thorax: e’etaient des ceufs. “ Maintenant se présente une objection. Les ceufs prouvent-ils l’état parfait de la mére? Selon moi, oui, jusqu’ & preuve du contraire. Je sais bien qwil y a quelques exemples du contraire dans les Orthopteres: ainsi M. Ch. Coquerel m’a montré un kakerlac pondant des cufs et n’ayant encore que des moignons d’élytres ; mais je ne cerois pas que dans Vordre des Hémiptéres on ait encore signalé pareille anomalie. M. Amyot veut qu'un insecte ne puisse étre parfait sans ailes; mais quentend-on par état parfait? I] me semble qu'il ne saurait y avoir d’ambiguité: c'est l'état de puberté, c'est le moment ott l’insecte jouit de toutes ses facultés, et celle de se reproduire est plus importante que celle de voler. Quant aux ailes, il est vrai qu’elles sont le signe patent de la perfection, mais elles ne sont pas indispensables : dans les Coléoptéres, nous en avons de fréquents exemples, et dans les Hémipteres la punaise des lits nous prouve tous les jours que certains insectes peuvent vivre, s’accoupler et mourir sans ailes. Dira-t-on quelle narrive jamais 4 l'état de perfection? D’ailleurs, pour les Halobates, naviguant le plus souvent & des centaines de leues de tout rivage, & quoi leur servirait d’étre ailés? Leur corps me semble destiné & se passer de ces aides aériens: les anneaux supérieurs de Vabdomen sont convexes, coriaces, et on distingue & peine la suture des premiers avec le thorax et entre eux: il ya bien de chaque cété une sorte de moignon d’aile, mais il est & Vétat rudimentaire et semble n’étre placé li que pour la forme. “Les especes qui m’ont fourni ces observations sont les Halobates flaviventris et sericeus, que M. Ch. Coquerel a trouvés ensemble, le premier beaucoup plus rare que le second, et presque toujours sur les Fucus, appelés vulgairement raisins des tropiques. Notre collegue, qui en a remarqué des millers, n’a jamais vu un seul individu ailé, parti- eularité qui ne lui aurait pas échappé.” X.— Car STAt. Nya Hemiptera. Ofversigt af Kongl. Vetenskaps-Akademiens Fordhandlingar. Elfte Argingen, No. 8, p. 238, 1854. “ Halobates, Esch. “1. H. lituratus: H. picto similis; sordide flavotestaceus ; thorace margine antico, lineis 4 fere basalibus abbreviatis, medis utrimque oblique transversis, curvatis, media 14 THE VOYAGE OF H.M.S. CHALLENGER. longitudinali, laterali utrimque subrecta, nigrofuscis ; femoribus anticis utrimque longi- tudinaliter, tibiis tarsisque totis nigricantibus. Long. 5, lat. 23 millim.—China.” [This species is not a true Halobates, but is the type of a new genus.—F. B. W. | XI.—Dr. Grorce Cart BERENpT. Die im Bernstein befindlichen organischen Reste. Bd. ii. p. 19, tab. ii. fig. 8, 1856. - | Dr. Berendt describes and figures an insect which he considers may perhaps be the larva of a Halobates or some allied genus. The figure shows rudiments of elytra and wings, besides other characters not belonging to Halobates. Under these circumstances, further consideration of it is not necessary.—F. B. W. | XII.—Cart Stat: Konglika Svenska Fregatten Eugenies Resa. Insekter. Hemiptera, p. 264, 1858. “Fam. PLOTERES. 1294, Halobates lituratus. “ Flavo-testaceus ; antennis basin versus exceptis, fuscis ; macula intraoculari obsoleta, vitta thoracis, scutelli margine basali tenuissime, lineis quatuor basalibus (intermediis longioribus, apicem versus sublatioribus), lineaque percurrente media et postice utrimque linea intus latiore, apicem versus angulata et in pectore continuata, hujus etiam linea laterali, tibiis tarsisque nigro-fuscis ; femoribus anticis intus et extus vitta fusca, apud ¢ incrassatis. ¢ ?. Long. 5, lat. 2? millim. “ Halobates lituratus. Stal, Ofv. af K. Vet.-Ak. Forh., 1854, p. 238. “ Patria : China (Wampoa). “HH, picto aftinis, pictura aliter distributa. Caput flavo-testaceum, maculis una majore vel duabus minoribus intraocularibus fuscis. Antennze corporis fere dimidia longi- tudine, fusca, basin versus flavo-testacese. Thorax flavo-testaceus, linea longitudinali media, margine antico et interdum macula utrimque prope lneam longitudinalem nigro- fuscis. Scutellum flavo-testaceum, lineis longitudinalibus, una media percurrente, unaque antice utrimque cum macula oblonga vel vitta suboblique longitudinali brunnes- cente coherente, margine antico anguste lieaque utrimque posteriore oblique longitudi- nali, apice rotundato-angulata et in pectoris latere retrorsum currente, nigro-fuscis ; pectore etiam linea percurrente striolaque disci utrimque longitudinalibus nigro-fuscis. Pedes fusci, femoribus flavo-testaceis, anticis utrimque fusco-vittatis, apud marem in- crassatis.” REPORT ON THE PELAGIC HEMIPTERA. a5) XITI.—Dr. Anton Doury. Zur Heteropteren-Fauna Ceylon’s. Stettiner Entomologische Zeitung, vol. xxi., p. 408, 1860. “103. EHalobates Stali, n. sp. “HH. supra niger, opacus; capite sordide flavo-testaceo, macula magna media, 3 anticis minoribus nigris, oculis fusco-fulvis, nigro-maculatis ; thorace antice maculis 2 semi- circularibus, postice 2 mediis parallelis longitudinalibus, 1 utrimque uti comma figurata aliaque utrimque transversali, semicirculari, tertia utrimque minore apice disci, tune in parte prope insertionem pedum una transversali, 2 longitudinalibus, 3 apicalibus, minori- bus flavo-testaceis ; subtus cum lateribus flavo-testaceis, his longitudinaliter nigro-strigatis, macula supra coxas anticas, lineisque 2 plus minusve latis femorum anticorum nigris ; antennis, pedibusque mediis posticisque nec non tibiis anticis nigrescentibus; rostro tlavo- testaceo, apice nigro.—7 millim.” [This is probably congenerie with H. litwratus, Stal.—F. B. W.] XIV.—Dr. Gustav L. Mayr. Reise der dsterreichischen Fregatte Novara um die Erde. Zoologischer Theil, Band ii. Abth. 1. Hemiptera, p. 177, 1866. “HALOBATES, Escu. “ Dorp., Abh. i, 1822. “ HT, lituratus, Stal. “ Halobates lituratus, Stal, Eug. Resa, Ins., p. 264 (1858). “ Hongkong. “Dr, Stal’s Beschreibung ist durch Folgendes zu erganzen : Die Schnabelscheide reicht nur bis zum Vorderrande der Mittelbrust ; die Vorderschienen haben am Ende einen zahnartigen Fortsatz und sind daselbst nicht erweitert (bei H. pictus, Herr.-Schaeff. soll dieser Fortsatz fehlen), zweites Tarsenglied der Vorderbeine unten nahe der Mitte mit einem Ausschnitte, in welchen die Krallen eingefiigt sind ; die Schenkel der vier hinteren Beine sind linger als die Schienen (wahrend nach Herrich-Schaeffer bei 4. pictus die Mittelschenkel kiirzer als die Mittelschienen sind). Da Dr. Stal angibt : ‘ H. picto afinis. pictura aliter distributa,’ so sollte man meinen, dass sich H. lituratus von dieser Art nur durch die Firbung unterscheidet. Wenn aber die von mir untersuchten Exemplare richtig bestimmt sind (was wohl vorauszusetzen ist, da Stal’s Beschreibung mit denselben itbereinstimmt), so finden sich bei H. lituratus Merkmale, welche diese Art von H. pictus wesentlich unterscheiden.” 16 THE VOYAGE OF H.M.S. CHALLENGER. XV.—GerorG Rirrer von FRAUENFELD. Verhandlungen der kaiserlichen und koniglichen zoologisch-botanischen Gesellschaft in Wien. Band xvii. pp. 456-460, Taf. xii. fig. 1-10. 1867. “ Halobates Wiillerstorffi, n. sp. Bei Cap Frio niichst Rio Janeiro 20-30 Meilen vom Lande. - “ Halobates flaviventris, Eschsch. In der Niihe der Nicobaren. “ Halobates lituratus, St. lim chinesischen Meere. “ Halobates micans, Eschsch. Vor Ceylon, beiliiufig 3° N. Br. “ Eschscholz hat die Gattung Hadobates in seinen Entomografien aufgestellt. Es ist das einzige wirklich und ausschiesslich im Meere lebende Insect, da ich ausserdem nur ein Paar Fliegerlarven kenne, die ihre Verwandlung im Seewasser bestehen, Belostomen aber, die 6fter schon im Meere gefangen wurden, bestimmt nur zufillig und ausnahm- sweise sich daselbst finden. Sie hiipfen auf der Oberflaiche des Wassers in grossen Schaaren gesellig in meilenweiter Entfernung vom Lande umher. “Hschscholz beschreibt und bildet 3 Arten ab: micans, sericeus und flaviventris. Templeton hat in der Trans. of the ent. Soc. eine neue Art. : ‘ Streatfieldana’ beschrieben. Zwei weitere Arten pictus Grm. und die in ‘ Eugenie’s Resa’ von Stal neuerlichst be- schriebene ‘lituratus’ unterscheiden sich von jenen vier einfarbigen Arten durch ihre bunte Zeichnung. Die von Am. Serv. als Halobates albinervus aufgestellte Art wurde von Gust. Mayr wegen der vorhandenen Fliigeldecken als Gattung Brachymetra abge- trennt. HH. sericeus und pictus sind in den wanzenartigen Insecten von Herrich-Schiffer auf, Taf. 286 abgebildet. “Tech habe die Seewanzen wihrend der Fahrt mehrfach beobachtet und mehrere Arten vom Fenster meiner Cabine aus mit einem Netze an einer langen Stange aufgefischt. H. lituratus St. fing ich auf der Fahrt von Manila nach Hongkong mitten im chinesischen Meere. Von einfarbigen Arten habe ich 3 beobachtet, und zwar eine, die fiir unbeschrieben halte, H. Wiillerstorffi bei Cap Frio niichst Rio Janeiro, ferner eine vor Ceylon in beiliufig 3° N. Br., welche ich zu H. micans, Esch. ziehe, und eine dritte endlich, in grosser Anzahl in der Nihe der Nicobaren, welche ich zu flaviventris Esch. bringe, obwohl sie nicht besonders nich dessen Beschreibung tibereinstimmt. Von dieser letzten von welcher Eschscholz nur 2 Weibchen sah, habe ich. beide Geschlechter und eine grosse Menge Larven gefangen. “Eschscholz sagt in seiner Gattungs-Diagnose : Tarsi antici triarticulati ; die Fiisse dieser Beine scheinen von oben betrachtet nur aus 2 ziemlich langen dicken Gliedern zu bestehen, aber an der Unterseite des zweiten liangern Gliedes bemerkt man noch ein drittes sehr kurzes, abstehendes Glied, das am Ende mit 2 gekriimmten Haken bewatl- net ist. REPORT ON THE PELAGIC HEMIPTERA. 17 “Dieses zweite Glied hat in seiner Mitte unten einen Ausschnitt, in dessen Grund die Doppelklaue eingefiigt ist, zwischen der eine gleichfalls gekriimmte feine Borste sitzt. Der unterhalb stehende, die Klauen nicht iiberragende Fortsatz ist schlank keglich. Ich habe nur nach starken Pressen bei volliger Zertriimmerung des Gliedes dieses Zipfchen abzutrennen vermocht. Es diirfte also vielleicht nicht als drittes Glied zu bezeichnen sein, um so mehr, als die Klauen am Grunde desselben sitzen (ligt 6: 95.10): “Teh will die neue Art und das Miinnchen von H. flaviventris, Esch. beschreiben, und den iibrigen das zur Ergiinzung Nothige beifiigen. “ HT, Wiillerstorffi, n. sp. (fig. 1, 2). “ Schwarz, aschgrau bereift, namentlich an den Seiten und am Bauch lichter seiden- gliinzend. Alle Beine gliinzend stahlblau. “ Kopf dreieckig, etwas schmiiler als das Halsschild. Die grossen schwarzen Augen jedoch weit dariiber vorstehend. Halsschild in der Mitte hinten und vorn eingeschniirt, mit 2 nur bei dem Miinnchen sichtbaren leichten Quereindriicken. Der hoch gewolbte Mittelriicken vorn etwas breiter als das Halsschild ; oval, bei dem Minnchen an der Seite stirker gebaucht, bei dem Weibchen daselbst etwas weniger. Der sehr reduzirte Hinter- leib beim Minnchen abgerundet, beim Weibchen mit einem grossen, bei allen Arten dieser Gattung gewohnlichen rautenformigen Anhang. Die schwarzen Fiihler (fig. 6) vier- gliederig. Erstes und zweites schlank, gleichdick, an der Spitze etwas geknoOpft, das erste zweimal so lang als das zweite, das dritte und vierte merklich verdickt, cylindrisch, an den Enden abgerundet; zwischen dem zweiten und dritten Gled eine kleine runde Abschniirung, die dem dritten Gliede angehért. Das dritte Glied merklich kleiner als das zweite. Das vierte etwas grésser als das zweite, mithin fast 14 mal so lang als das dritte. Vorderbeine kriftig ; Hiiften der Mittelbeine sehr kurz, jene der Hinterbeine mehr als 3 mal so lang, cylindrisch. Schenkel der Mittelbeine dicker als jene der Hinterbeine und 12 mal so lang. Schienen diinner wie die Schenkel, doch auch diese an den Mittelbeinen etwas dicker als an den Hinterbeinen; an beiden gleichlang. ‘Tarsus zweigliedrig; an den Mittelbeinen das erste Glied wenig kiirzer als die Schienen, etwas gekriimmt, zweites Glied sehr kurz. An den Hinterbeinen beide kurz. Siimmtliche Beine des Miinnchens sind glinzend stahlblau ; beim Weibchen sind jedoch nur die Vorderbeine und die Hiiften der Hinterbeine stahlblau, Schenkel und Schienen dieser zwei Beinpaare, die auch etwas linger als beim Minnchen sind, schwarz, mit sehr schwachem blauen Schein. Fiisse und Fiihler sind zart behaart. “ Lang 4 mm., breit an der dicksten Stelle 2°5 mm. Schenkel der Mittelbeine lang 4°5 mm. “? Lang 4°3 mm. mit dem rautenformigen Anhang, breit an der dicksten Stelle 2°35 mm. Schenkel der Mittelbeine lang 5 mm. “ FH, micans, Esch. Von dieser Art habe ich gleich Eschscholz nur Miinnchen gefangen; (ZOOL, CHALL. EXP.—PART XIxX.—1883.) T3 18 THE VOYAGE OF H.M.S. CHALLENGER. sie gliecht sehr der so eben beschriebenen H. cyanipes,’ nur sind die Fiihler (fig. 5), die gleichfalls zwischen dem 2 und 8 Glied eine rundliche Abschniirung haben, schlanker. Das erste Glied ist linger als bei H. Wiillerstorffii, dagegen das zweite und dritte fast gleichlang. Auch die Beine sind etwas schwiicher als bei jener Art, doch so ziemlich von gleichem Verhialtniss; sie unterscheiden sich aber durch die Fiarbung, indem sie wie Eschscholz angibt, schwarz sind, und nur die Vorderschenkel einen bliulichen Schein haben. Die Farbung des Thieres selbst, die Eschscholz als ‘schwarzlichgrau mit Mes- singglanz, Hinterleibsringe weissgrau, unterseite das ganzen Korpers silberweiss’ angibt, stimmt nicht ganz genau. Meine Exemplare sind aschegrau bereift, ohne Spur eines gelb- lichen Glanzes, und auf der Unterseite wohl heller, doch keineswegs silberweiss. “ ¢ Lang 4mm., breit an der dicksten Stelle 2°25 mm., Schenkel der Mittelbeine lang 4°6 mm. “ H. flaviventris, Esch. (fig. 4). “¢ Oval, am Riicken nicht sehr hoch gew6lbt. Oben licht aschgrau bereift ; am Kopf neben den stark hervorragenden, bei verschiedenen Individuen theils hell, theils schwarz- braunen Augen, beiderseits ein braungelber Fleck, die sich am Hinterrande mit einer, schmalen Linie vereinigen. Auf der Seite und unten silberig gliinzend. Der ganze Bauch, die Unterseite des Halsringes, die Hiifthécker der siimmtlichen Beine und ein Mittelstreif (fehlt beim Weibchen), der an der Bauchwurzel breiter ist und iiber die ganze Mittelbrust verschmiilert bis zum Halsring zieht, gelb. Die sehr zarten Fiihler (F. 7), die nicht jene rundliche Abschniirung wie die beiden vorigen Arten, zwischen dem zweiten und dritten Glied besitzen, an den Wurzeln, hiiufig bis zur Hilfte des Gliedes gelb. Die kriiftigen Schenkel der Vorderbeine gleichfalls an der Wurzel, und eben so oftmals ziemlich ausgedehnt gelb, sonst obenauf schwarz, unten aber durchaus gelb. Die vier sehr zarten Hinterbeine schwarz, nur die Hiiften auf der Unterseite gelb. Der After bildet ein stark vorragendes Zipfehen, Lang 4 mm., breit an der dicksten Stelle 2°25 mm., Schenkel der Mittelbeine 4°6 mm. “Beim Weibchen habe ich nur zu bemerken, dass auch hier die Fiihler an der Wurzel stets mehr oder weniger ausgedehnt gelb sind, wovon Eschscholz nichts erwiihnt, sowie dass die Fiihlerglieder alle gleichdick sind, und das 2, 3, 4 Fiihlerglied gleichlang, wiihrend sie Eschscholz ungleich angibt. Auch die Hiiften der Vorderbeine, sowie die Unterseite des Halsringes sind wie beim Miinnchen stets gelb, Das iibrige stimmt mit dessen Beschreibung iiberein. , “Ich bin bei der ausserordentlichen Genauigkeit der Angaben Eschscholz’s nicht ganz sicher, ob die von mir gefangene Art wirklich zu dessen flaviventris gehért, wollte jedoch auf diese Abweichungen hin keinen neuen Namen geben. “Die Larven (F. 3), die ich zalreicher als das ausgebildete Thier gefangen, sind nur wenig kleiner und an denselben kein Geschlechtsunterschied zu entnehmen. Sie sind 1 “ Cyanipes” is evidently a lapsus calami for “ Wiillerstorffi.”—F. B. W. REPORT ON THE PELAGIC HEMIPTERA. 19 lederhiutig, mit einzelnen Chitinplatten, und zwar 2 querovale auf dem Halsring; 2 langlichovale auf der Vorderhiilfte des Mittelriickens, hinter jedem derselben ein quer nierenformiges ; auf den 4 ersten der 7 deutlich untershiedenen Hinterleibsringe an der Seite eine sehr kleine rundliche, eine liingliche obenauf am Hiifthécker der Hinterbeine. Diese simmtlichen Platten sind aschgrau bereift, die Hautdecke dazwischen braun, lings den Seiten des ganzen Leibes gelb, weiss schimmernd, die letzten Hinterleibsringe hellgelb. Die Afterdecke ist schwarz, mit einer breiten gelben Querbinde, von welcher nach vorn eine gelbe Mittellinie geht, die das Schwarz des vordern Theiles mitten trennt. Die Unterseite ist ganz ledergelb. Die Fiihler sind wie beim ausgebildeten Thiere, nur matter schwarz. Auch die Vorderbeine sind an der Wurzel gelb, haben jedoch nur ein Tarsenglied, das durch einen Einschnitt unten, etwas ausser der Mitte einen spitzen Zahn trigt. Die Hiiften der Hinterbeine unten gelb. Die Farbe siimmtlicher Beine matt briiunlichschwarz. “€ Ausgebildetes ¢ 4°2mm. lang, breit 2°4 mm, Schenkel der Mittelbeine 5 mm. lang. “ $1 4-1 mm, lang mit dem Anhang, 1°9 mm. breit, Schenkel der Mittelbeine 5:1 mm. lang.” [This is the most important paper on the subject since the genus was founded, but the author has curiously adhered to the original error of confounding the sexes. It is to be noted that the species he refers to flaviventris, Eschscholtz, is not that species, —a fact of which he seems to have had some suspicion, but he was unwilling to found a new species without a certainty that he was right in so doing,—a very commendable cautiousness.—F. B. W. | XVI.—Professor Enrico Hittyer GIGLio.t. Breve cenno sulla distribuzione geografica dell’ emittero Halobates, Eschscholtz. Budllettino della Societa, Entomologica Italiana, Anno secondo, p. 260, 1870. “Sembrera strano il fatto di cogliere un insetto in alto mare, a grandi distanze da qualsiasi terra; eppure l’entomologia non manca di rappresentanti anche in mezzo all’ Oceano, e di contribuire essa pure il suo obolo alla fauna pelagica. “Sin dal 1822 Eschscholtz descrisse col nome di Halobates”? un insetto che vive camminando sulla superficie mobile dell’ Oceano, come fanno le communi Hydrometra sulle nostre acque stagnanti. “Le affinita’ del genere Halobates sembrano essere col genere Gerris di Latr. ; esso infatti comprende insetti piccoli, atteri, con elitre rudimentarie, addome corto e conico, i quali vivono nei mari tropicali. Westwood’ li considerava come insetti ancora allo 1 The sign ¢ is here evidently given in mistake for 9—F. B. W. 399 2 Entomographien, 1 Lieferung, Berlino, pp. 106-111, tab. ili. fig. 3-5, 1822. 3 Introduction Modern Classifie. of Insects, 11. p. 470 (Nota). 20 THE VOYAGE OF H.M.S. CHALLENGER. stato di larva ed Amyot* é dell’ istesso avviso, mentre Blanchard sostiene l’opinione dell’ Eschscholtz, giudicandoli insetti perfetti. Fairmaire’ tra individui portati dal Signor Coquerel dai mari del Madagascar, trovd due femmine coll’ addome pieno di uova, le quali come molte centinaie d’individui gia esaminati non avevano ali. Dunque debbone per questo essere considerati larve ? Cuz bono le ali ad un insetto che vive in alto mare 4 “To sono interamente dell’ opinione del Fairmaire ; e chi ha veduto questi emitteri ad enormi distanze da qualunque terra non pto pensare altrimentri. ~ “ Di questo genere varie specie sono gid stato descritte. Io non intendo entrare in argumento cosi intricato che verra trattato da persone assai pil competenti di me nella monografia entomologica del viaggio della ‘ Magenta’: intendo soltanto accennare alle localita ove trovai gli Halobates durante il mio viaggio di circumnavigazione. E siccome largomento @ nuovo, credo che cid non sara privo d’interesse. “ Pescai il primo Halobates nell’ Atlantico Australe il 29 dicembre 1865 in lat. 16° 11’ Sud, long. 36° 00’ Ob. Parigi; a circa 400 miglia dalla costa Americana. I] giorno seouente ne furono presi altri, ma non erano numerosi. “Nel maggio 1866, altri Halobates furono pescati nello stretto di Banca, golfo di Siam, ed in vicinanza delle isole Pulo Condore, ove il mare per larghissimo tratto era coperto da Trichodesmium, sparso alla superficie dell’ acqua come minuta segatura. * 1] 10 febraio 1867 entrammo di nuovo nell’ Oceano indiano, in cui trovammo un Halo- bates abondantissimo. Dal 12 febbraio (in lat. 11° 33°8., long. 106° 40’, E. Gr.) al 17 dello stesso mese (in lat. 15° 59’ §., long. 105° 48’ E. Gr.) entro gli stesso limiti il mare era sparso di fioechi di Trichodesmium. “'Traversato il Pacifico, incontrammo di nuovo il nostro emittero abbondante a qualche centinajo di migla dalla Costa Americana, dal 29 agosto (in lat. 21° 27’S.) al 6 set- tembre (in lat. 29° 21’8.). “ Finalmente, ?Halobates fu ripreso nell’ Atlantico, nel viaggio di ritorno (gennaio 1868), in due occasioni ; il primo in lat. 26° 38’ 8., il secondo in lat. 4° 28’ Nord. “ Ad un esame non minuzioso tutti questi Halobates mi sembravano appartanere ad una sola specie. “ Concluderd col dire come questi strani insetti sono sparsi Jungo la zona tropicale in tutti 1 mari, e non hanno certamente bisogno di alghe per sostenersi sull’ acqua, come sembra voler asserire il Coquerel. Jo non trovai un solo Halobates nel Mar di Sargasso, ed il Trichodesmiwm col quale lo trovai associato due volte, non @ certamente capace di servir loro da zattera. “ Un ricca serie d’individui dalle diverse localit&’ venne reportata, ed in un colle altre collezioni zoologiche del viaggio della Magenta si trova nel R. Museo di Torino.” [Three of Dr. Giglioli’s specimens—kindly lent to me by the Turin Museum—are 1 Hist. Nat. des Hémiptéres, p. 412. * Ann. Soc. Ent. de France, sér, 2, t. ii. p. XXvi., 1848, REPORT ON THE PELAGIC HEMIPTERA. 21 referrible, partly to H. Wiillerstorffii and partly to a new species. What the others may be, I of course cannot say, but it is not improbable that there are other species amongst them.—F. B. W.] XVIIL—Rosert M‘Lacuian, F.R.S. The Entomologists Monthly Magazine, vol. vii. 1870-71. After giving a summary of Professor Giglioli’s paper, the author proceeds to say : “These notes have a peculiar interest for me, as exciting reminiscences of a voyage of thirteen months’ duration I made when a youth, in 1855-56. This voyage was marked by a most immoderate amount of calms (in one case extending to thirty consecutive days, in the hottest part of the China Sea), and I lost no opportunity of fishing up—and, I am sorry now to say, casting away,—the, to me, wonderful forms always floating around. Long before crossing the line, on the outward voyage, I was struck by small whitish creatures which often appeared coursing with great rapidity over the surface of the ocean ; at length one was captured, and I well remember my astonishment on finding it was a spider-like insect, of the affinities of which I then knew nothing. They disap- peared, or rather were lost to view, as soon as a breath of wind caused a ripple on the surface, but were common in that most unpleasant form of sea-disturbance in which there are great ‘ smooth’ waves, the effect of a recent storm, but with no present wind. In the Atlantic, Indian, and Pacific Oceans, it only needed the required state of the sea to bring these merry coursers to view, and certainly often without the presence of the smallest piece of floating sea-weed. Those who have voyaged will bear me out when I say that, excepting in the mysterious Sargasso-sea, in the course of the oceanic currents, and in the vicinity of land, sea-weed may be looked for with as much chance of finding it as daisies. I should here state that the brilliant white appearance of the insect on the ocean is caused by the pellicle of air that surrounds it, the creature itself being blackish. If these notes should be read by any one of those ‘ who go down to the sea in ships,’ I would remind him that, if he can throw any light upon the life-history of this most wonderful insect (how many species there may be I know not), he will confer the utmost benefit upon natural science. The Trichodesmium alluded to by Giglioli is a minute confervoid plant which sometimes covers the surface of the ocean like fine sawdust.” XVIII.—Professor Kart SEMPER. The Natural Conditions of Existence as they affect Animal Life, p. 144; also note on p. 454, 1881. “In the Pacific Ocean and Philippine Sea I have myself often found various insects and even spiders in the sea, sometimes swimming in great numbers on the surface, sometimes 22 THE VOYAGE OF H.M.S. CHALLENGER. creeping between rocks under water by the shore. A bug of the genus Halobates (fig. 35) is particularly common in these seas, besides the above-mentioned larvee of flies. This genus was discovered by Eschscholtz, and now includes fourteen species living in seas the most remote from each other. The species in question runs about like our Water- Bug, Hydrometra, in great numbers and in every stage of development, on the high seas hundreds of miles from land.” And a note on p. 434: ‘ Hight species of the genus, as I am informed by my friend Dr. Hagen, have been described ; that described in the text and discovered by me is a new species and the largest of all. They are found in the Atlantic, Indian, and Pacific Oceans, as well as in the Chinese Sea, but only in tropical or sub-tropical regions.” [ Professor Semper tells me that the woodcut given in his work is a correct representa- tion of the species referred to, and that the expression ‘‘now includes fourteen species ” was written by mistake. The species in question probably belongs to a new and unde- scribed genus.—F. B. W.] In addition to the literature reproduced above, there are various other references to the genus, but as they contain nothing of importance it is unnecessary to mention them further. In addition to the specimens taken by the Challenger expedition, I have had the advantage of having been able to study specimens belonging to several museums and private collections, both in Britain and on the continent of Europe ; and my best thanks are due to all those who have in this and other ways assisted me. The museums to which I am indebted for the loan of specimens are the following :—Berlin (through Dr. Peters), Brussels (through M. A. de Borre), Liverpool (through Mr. T. J. Moore), Oxford (through Professor Westwood), Stockholm (through M. C. Aurivillius), Turin (through M. L. Camerano), Vienna (through Dr. Rogenhofer). I have also to thank Professor Westwood, of Oxford; Dr. Signoret, of Paris; Mr. J. W. Douglas, of London ; and Dr. G. Hay, of Aden, for the loan or gift of specimens from their private collections ; and for information and other assistance, Mr. John Murray of the Challenger; Mr. R. M‘Lachlan, F.R.S.; Dr. Murie, the Librarian of the Linnean Society; Dr. Dohrn, of Stettin; M. L. Fairmaire, of Paris; Dr. G. L. Mayr, of Vienna; Mr. C. Ritsema, of the Leyden Museum ; Professor Semper, of Wiirzburg, Mr, J. T. Carrington, F.LS. ; the naturalists of the British Museum; and lastly, Mr. Edwin Wilson, for the painstaking skill with which he has drawn the illustrations. II], ANATOMY AND DESCRIPTION OF GENERA AND SPECIES. On examining the various species that have been placed in the genus Halobates, it soon became evident that they could not with propriety be retained in one genus, and that, in fact, they make part of at least three genera. As, however, this paper deals only with those genera, some, if not all, of the species of which are marine, two genera only require to be noticed. These are Halobates proper and a new genus Halobatodes, Had the species of the latter genus not existed, there would also be grounds for establishing a new sub-family for the genus Halobates. As it is, Halobatodes (of which the typical species is Halobates lituratus, Stal) and Stephania (a new genus proposed for the recep- tion of Halobates pictus, Germar) form connecting links between Halobates and the more typical genera of the sub-family Hydrobatina, in which Halobates has hitherto been placed. To retain it in this position, however, some modification in the definition of the sub-family will be necessary ; as, for example, in this respect, that, while the Hydro- batina are said to have two-jointed tarsi, Halobates has the hinder tarsi only one- jointed. The two genera under consideration may be thus distinguished :— 1. Body thickly clothed with short pubescence ; front tibia with a triangular dilatation near the apex ; middle tibia and first joint of tarsus with a long fringe; hind tarsus with one joint, é 5 ° 5 A : 3 F Halobates 2. Body more sparsely clothed with short pubescence ; front tibia cleft, but not with a triangular dilatation at the apex; middle tibia and tarsus without a long fringe; hind tarsus with two joints, é ; : , : , : Halobatodes. HALOBATES, Eschsecholtz, Entomographien, i. p. 106, 1822. Body oval or oblong. Head shortly triangular. Antenne four-jointed, with two intermediate jointlets. First joint always the longest. Rostrum four-jointed ; first and second joints very short, the latter ringlike ; third joint the longest. 24 THE VOYAGE OF H.M.S. CHALLENGER. Eyes large, situated at the back of the head, and resting partly on the pronotum. Prothorax transverse, much broader than long, not confluent with the mesothorax. Mesothorax and metathorax together cylindrical, coalescent, the boundary between them searcely distinguishable ; no scutellum nor scutellar process. Elytra and wings always wanting. Front legs short, rather stout. Tibia with a triangular process near the apex. Tarsus two-jointed ; second joint with claws inserted about the middle. : Middle and hind legs long and slender, inserted at the sides of the posterior end of the thorax; the hind legs inserted above the middle legs. Middle legs with tibia and first jot of tarsus furnished with a fringe of long hairs ; tarsus two-jointed, the second joint clawed before the tip. Hind legs with one-jointed tarsus clawed before the tip. Abdomen very short, first three segments covered above by the metanotum. Apex of the abdomen in the male with a conspicuous rhomboidal appendage. DETAILS OF STRUCTURE. Halobates presents a peculiar appearance on account of the great development of the thorax in comparison with the abdomen, thus approaching in facies the larvee of some other genera of Hydrobatina. The body is covered with very short and close pubes- cence of a grey colour, which is the predominating tint of the species, few of which have any conspicuous markings, at least on the upper surface. In all there are two reddish or yellowish spots at the back of the head, but in most cases these are not conspicuous. Several of the species have pale markings on the under side. THe HEAD AND ITs APPENDAGES. The Head viewed from above is shortly triangular; viewed from the side, the vertex is more or less convex, while the frons is sloped very much downwards. The vertex is convex, at least in the middle, but is usually widely but shallowly depressed on each side near the hind margin; while there is another more slight depression before the middle lobe of the face. In the female the latter depression is more conspicuous than in the male. The posterior depressions do not extend so far as the orbits, the inner sides of which are slightly tumid. In the posterior depressions is generally a rufous spot, usually ill-defined and not conspicuous, but forming in a few species a conspicuous, oblique, reddish-yellow mark*on each side of the middle of the back of the head. The hind margin between the eyes is convexly rounded, and in one or two species the edge is more or less narrowly elevated. The front of the head is sloped downwards, and is nearly, but REPORT ON THE PELAGIC HEMIPTERA. 25 not quite, perpendicular. The middle lobe of the face is at least twice as broad as the side lobes, a little dilated at the apex, somewhat prominent and truncate. The side lobes are sub-triangular and rather inconspicuous. The sides of the head are blunt and not margined. On each side of the upper surface of the head are three more or less conspicuous black points, rising above the pubescence, one at the posterior angle near the eye, one situated more inwardly, and in a line with the front of the eyes, and one near the inner angle of the base of the antenniferous tubercles (Pl. HI. fig. 7). Under the microscope these spots are seen to be tubercles destitute of the pubescence which covers the rest of the head. The summit of each tubercle is concave with raised margins, and, situated within the rim and to one side, is a smaller tubercle, bearing a short hair (PI. III. fig. 8). In two species (wiillerstorffi and sericeus) the apex of these tubercles is from ‘02 mm. to *022 mm. in diameter, and the length of the hair ‘06 mm. to "10mm. On examining one of the tubercles from the inside of the head it appears to be hollow, with the base of the hair protruding (unless this is an optical illusion) for some way into the cavity. It is probable that these tubercles are organs of one of the senses, possibly that of sight. The situation of the posterior ones corresponds with that of the ocelli, with which the Hemiptera are frequently provided, but when these are present in the Heteroptera they are never more than two in number, and true insects in the adult condition have very rarely, ifever, more than three,! though there is reason to believe that the anterior ocellus when present really consists of two ocelli coalesced. This anterior pair would correspond to the middle pair in Halobates, and the anterior pair (in this genus) has disappeared in other insects (as has in some cases the middle pair, and in others all the pairs), though still existing in some groups of the Arthropoda. The nature of these tubercles seems to have been hitherto overlooked, and it is much to be desired that naturalists who have the opportunity should examine the structure in fresh specimens, and ascertain with what part (if any) of the nervous system they are connected. The Eyes are large and prominent, situated at the hinder angles of the head, and ex- tending for about one-third of their length behind it, resting on the sides of the thorax. The orbit, especially above and below, and in a less degree in front, is provided with several irregular series of long, strong hairs, curved at the tip, the hairs nearest the eye being the largest. Viewed from above, the eye is semi-circular in outline, with the inner edge slightly convex ; viewed from the side it is roundly oval; viewed from below the outline is similar to that from above. The facets of the eye are hexagonal. In wiiller- storffi their diameter is about ‘035 mm.; in sericeus about 025 mm. ‘The outer free periphery has (in two species) about 25 facets. The Antenne are attached to the inner anterior apex of conspicuous tubercles, which are situated on the side of the head between the eyes and the apex of the face. These 1 Some Aphides are said to have six. (ZOOL, CHALL, EXP.—PART XIx.—1883.) AP 26 THE VOYAGE OF H.M.S. CHALLENGER. tubercles viewed from above are irregularly conical, and connected with the vertex by a tumid ridge, which is more distinct in the female ; viewed from below the tubercle points downwards, and the tip extends a little beyond the base of the antenna. Round the in- sertion of the antenna the tubercle is furnished with a coronet of stiff hairs, curved at the apex. The antennz themselves are at least half the length of the body, and are four- jointed, with two intermediate jointlets (PI. II. fig. 1), one between the second and third joints of the antennze, and one between the third and fourth ; in each case the jointlet belongs to the joint preceding it. In one species the jointlets are said, but I think erroneously, to be absent.” The first joint is the longest, and often nearly, and sometimes quite, as long as the other three joints taken together ; very narrow at the extreme base, thick above the base, then narrowing to the middle, and often slightly imcrassate at the apex ; usually shghtly curved ; covered with numerous semi-adpressed hairs, except at the extreme base; the apex with stronger and longer hairs. The other joints have similar pubescence to the first, except that the fourth has not stronger hairs at the apex. These joints vary in length and thickness in the various species, but usually the second is gradually incrassate from base to apex; the third is thicker than the second, and often shorter; and the fourth is generally the thickest of all, sometimes incrassate upwards, and sometimes attenuate from the middle upwards. The jointlets have a finer integument (not furnished with pubescence) than the true joints, and are usually of a paler colour than these. That between the second and third joints is narrow at the base and widens to the apex; the other is much smaller, and ring-hke. In some species the antennz are provided with a few fine spines. The Rostrum is four-jointed, and reaches to the front margin of the mesosternum. The labrum is pentagonal, the basal sides oblique, and the apical sides forming a triangle; it reaches to or beyond the apex of the second joint of the rostrum. The first joint of the rostrum is stout, and broader than long. The second is ring-lke, and less than one-half the length of the first. The third is much the longest, stout, widened a little above the base, then diminishing to the apex. The fourth is much shorter than the third, less stout, and triangular in outline. The apex terminates in three short processes, one above and two below (PI. IL figs. 2 and 3). The upper process (between which and the rest of the joint is a rather ill-defined transverse suture) is the broadest, and is rounded at the end; the two under processes are gradually narrowed to the end, which is gently rounded, their inner margins are sub-parallel, and their tips are shortly longitudinally striate. Between them is the end of the furrow in which the mandibles he. In a line with the inner edges of the two inferior processes the margins of the furrow for the mandibles are longitudinally thickened, and have in the terminal joint of the rostrum a dark spiral line running round each (PL. HI. fig. 3). This spiral line is not continued into 1 See the description of Hulobates frauenfeldanus, postéa, REPORT ON THE PELAGIC HEMIPTERA. 27 the third joint, but in the latter the furrow is finely transversely wrinkled. The integu- ment of the fourth joint has several rows of a few rather stout hairs with tubercled bases. The Mandibles (Pl. Ill. fig. 4) seem to be triquetrous, with one side broader than either of the other two, and are scarcely dilated at the apex, which is very hard but not extremely finely pointed. On the outer edge, between the narrow sides, is a row of saw- like, back-pointing teeth of unequal leneth. These teeth gradually increase in length from the apex backwards, the fifth or sixth being the longest ; after that they rapidly decrease in length till they become little more than slight elevations of the edge of the mandible. In number they vary in different species, but the average number is probably about twelve. In one species (wiillerstorfi) the breadth of the mandible a little behind the apex and across the narrower side is about ‘012 mm. and on the broader side about ‘024 mm.; in another species (sericeus), the breadths are respectively about 012 mm. and 018 mm. The mandibles can be traced back from the base of the rostrum into the head. On entering the head they suddenly diverge, the space between them being about as broad as the base of the rostrum. They then go nearly straight back- wards to a point on a level with the base of the antenniferous tubercles, and are then suddenly bent forwards and outwards, the portion after the abrupt bend being either gradually dilated or split into several portions which diverge a little. This is the appear- ance presented by specimens mounted in Canada balsam, and lack of material has unfor- tunately prevented me from attempting to dissect out the parts. The Maxille (or the organs which in the Hemiptera are supposed to represent the first pair of maxillze) are much more complex in structure than the mandibles. Though often, like the mandibles, protruded from the apex of the rostrum, they can be retracted at least so far as that their tips reach only to the apex of the third joint of the rostrum. Though not inseparably united to each other, the two maxillze are yet for a considerable portion of their length so closely connected that they form but one organ. Moderately magnified and viewed directly from above, this appears to be a rather blunt and stout bristle lying between the mandibles, but when a higher magnifying power is used, the structure is seen to be rather complex. As the specimens which I have examined are mounted in Canada balsam, and all the parts do not lie in the same plane, and as moreover I have not had an opportunity of making transverse sections, the following description (made with the aid of an amplification of 900 diameters), is probably only approximately correct. Viewed from above the organ presents the appearance of four parallel lines, the distance between the inner two being rather greater than between the outer and inner on either side (Pl. II. fig. 5). Towards the apex the outer and inner line on each side approach each other, and form a point which curves rather abruptly inwards, the point on one side overlapping and touching the point on the other, thus forming a rather blunt apex to the organ. On the outer edges, from the tip for a considerable way backwards, are a series of fine, rather irregular hairs, at first directed outwards and a little backwards, and 98 THE VOYAGE OF H.M.S. CHALLENGER. then bent backwards. Between the outer and inner line on each side, is a series, beginning at the apex, and running back for a considerable way, of somewhat semilunar- shaped tubercles (Pl. HI. fig. 6); while between the two inner lines is a close series of fine curved transverse lines, below which may be seen—by altering the focus—another series of similar lines, whose direction from side to side is a little different. Ifthe organ is viewed in profile, the appearance is altogether different, as each maxilla exhibits on one side a series of comb-like teeth, which, beginning at the curved apex, runs back for a considerable way (Pl. IIL fig. 6,a). What I conceive (perhaps erroneously) to be the real structure of the organ is this. Each maxilla consists of a fine tube, longitudinally open on the inner side and fringed on the outer (from the apex for some distance), with fine back-pointing hairs. The fine curved transverse lines which are seen in the central longitudinal space of the organ are fine curved hairs, which cross from one maxilla to the other, and of which there are on each maxilla a series both above and below (PI. III. fig. 5,a). The semilunar-shaped tubercles are the comb-like teeth viewed directly from above, and which can only be properly made out when the organ is seen partly in profile. On tracing the organ further back, but while it is still cluded in the rostrum, both the back- pointing lateral hairs and the comb-like teeth disappear, but the inner series of curved hairs are continued. On tracing them backwards into the head the maxillz can be seen to gradually diverge, and each of them then appears as if finely transversely striate in the middle line. Gradually and slightly dilating, and continuing to diverge, they can be traced backwards into the mesothorax for some distance. The breadth of the maxillz a little behind the apex is in serzceus about °025 mm. and in the larva of hayanus about ‘014 mm. The under side of the head is flatly convex, with a concave hind margin. The gula is broad, reaching to the hind margin. In form it varies somewhat in different species ; sometimes the sides are slightly elevated, and sometimes there is a central longitudinal obtuse keel. THe THORAX. The thorax constitutes by much the largest part of the body, and increases in width more or less from the front to beyond the middle. Of the three segments which compose it, two only can be easily distinguished, since the mesothorax and metathorax are coalesced, while the prothorax and mesothorax are quite distinct from each other. The Prothorax. The Pronotum is transverse and collar-like, the length in the middle being two to three times less than the breadth, which is less than the head with the eyes. The front margin is usually rather strongly concave between the eyes to receive the head ; REPORT ON THE PELAGIC HEMIPTERA. 29 ~e the hind margin between the posterior angles is also concave, but often only slightly so, and in every case less concave than the front margin. The sides are a little oblique, so that the pronotum is a little wider behind than in front; gently rounded and convex, with the anterior and posterior angles also rounded. The disk is somewhat convex. or flat, somewhat slightly raised longitudinally in the middle line, or with a finely impressed line there. On each side of the middle line there is frequently a more or less distinct small transverse fovea situated a little behind the front margin; in some cases there is a larger fovea on each side, situated behind the anterior fovea. These foveee may be of post-mortem origin. One species is described as being provided with three longitudinal furrows. Sometimes the pronotum is depressed in the middle of the hind margin. _ Its shape varies a little in the sexes, The Prosternum is rather shorter than the pronotum, the front margin is less con- eave, and the hind margin is slightly convex. Of the disk the outer third on each side (except the extreme margin) is occupied from the front to the back by the large swollen acetabula of the front legs. The middle third is more or less strongly elevated on the longitudinal middle line. The acetabula, viewed from the side, are perpendicular or slightly oblique behind, where they are highest; and from the back to the front present a strongly convex out- line. Viewed from the front they are somewhat triangular in outlne. The opening of the acetabula looks backwards, and a little inwards, and rests behind against the meso- sternum. The anterior rim has a large triangular notch (Pl. I. fig. 8, ac.), whose apex reaches to within a short distance of the front margin of the prosternum. From its apex a slit or suture proceeds to, or almost to, the front margin. The Mesothorax and Metathorax. These two segments are coalesced, and together occupy frequently about three-fifths of the entire length of the body. They form also by far,the broadest and deepest part. The suture between them is most frequently indicated merely by a sharp short trans- verse impression (not always to be discerned) situated on each side within, and a little in front of, the ridge leading to the hind legs. Below no part of the metathorax is. visible. The Mesonotum is more or less distinetly wider in front than the pronotum. The front margin is convex in the middle, and then concave at each side to receive the posterior angles of the pronotum ; the anterior angles are produced a little in a forward direction. The sides are rounded and convex, and the width increases backwards— varying a little according to species and sex—till the greatest width is attained at, or a little before, or a little behind, the middle. The disk is frequently more or less convexly swollen (more rarely nearly flat), and is highest in the middle anteriorly. Sometimes there is a very fine impressed longitudinal central line. Posteriorly the mesonotum with the metanotum slopes more or less rapidly backwards between the insertion of the legs. 30 THE VOYAGE OF H.M.8. CHALLENGER. The middle and hind legs are inserted together at the sides of the posterior end of the thorax, but the hind legs are inserted above the middle legs, and their acetabula extend a little further back than the middle acetabula (PI. I. fig. 8,2? y). The middle acetabula, which occupy the lower posterior hind angles of the thorax, are, viewed from the side, cylindrical, anda little broader than long. Above they are covered by the hind acetabula. Viewed from below they are cylindrical, jommed on the inner side by the concave hind margin of the mesosternum, which is continued nearly to the apex of each acetabulum. The opening is nearly circular, and looks backwards. On the outer side of the middle line below is a suture or slit of greater or less length. The hind acetabula oceupy the upper posterior angles of the thorax, and are cylin- drical, longer than, but not so stout as, the middle acetabula, behind which they extend for about half their length, reaching to the apex of the middle coxe. The posterior half of the acetabulum is slightly hollowed below, where it impinges on the middle coxa. Between the middle and hind acetabula is a deep narrow longitudinal furrow, anteriorly forked, the branches being less deeply impressed. The upper branch is the longer, and goes upwards and alittle forwards, and marks the base of the acetabulum. The lower and shorter branch runs forwards and a little downwards, and is formed for part of its length by the slit-like opening of the mesothoracic spiracle. In wiillerstorffi the sht of this spiracle is about ‘2 mm. long; and in sericeus 16 mm. The opening of the acetabulum is circular, and looks backwards and a little inwards, the free ends of the acetabula bemg nearer together than their bases. Lying on the inside of the hind acetabulum is a narrow, almost parallel-sided plate, rather longer than the acetabulum, pointed in front and truncate behind; and divided from the acetabulum on the outer side and from the thorax and abdomen on the inner side by deep narrow furrows. The surface of the plate is not horizontal, but usually slopes more or less steeply to the inside, so that the outer edge is on a level with the upper surface of the hind acetabulum. In some cases, however, the slope is reversed, more especially in gravid females. Posteriorly the plate reaches beyond the end of the hind margin of the thorax, and the transverse impression or suture between the thorax and abdomen is continued across it. The situation of the smaller posterior part of the plate thus marked off varies a little in the sexes, and even in some of the species. In the male it is usually opposite the first free abdominal segment, and more rarely opposite (e.g., in Halobates sericeus) the second free segment, which is its usual position in the female. In the latter this part of the plate is also smaller and more detached. Beyond this detached portion traces of similar plates may be seen at the sides of the basal free abdominal segments. It is evident, therefore, that the plate and its continuation are formed by the pleura (or epimera) of the thoraxand abdomen. By some writers this plate has been described as the rudiments of the elytra and wings ; and as these organs in insects are expansions of the sides or pleura of the thorax, this view is in a limited sense correct. As Halobates, however, REPORT ON THE PELAGIC HEMIPTERA. 31 has never been found with elytra or wings, and has probably never possessed them, it will, on the whole, be as well not to consider the plates in question to be rudimentary organs. Between the plates the thorax diminishes in width backwards, and is marked on each side by transverse impressions, deepest at the sides, and rarely going across from one side to the other. These impressions indicate the position of the first three segments of the abdomen, which are covered by the integuments of the thorax. The Mesosternum is more or less flat. The anterior angles are somewhat tumid, and have within them (at least sometimes), a short oblique furrow, in which lies the base of the anterior trochanter. The hind margin is more or less widely and deeply concave. No part of the metathorax is visible below. THe ABDOMEN. The abdomen, viewed from above, is small, rather depressed posteriorly, and, as regards the portion not concealed by the thorax, sub-triangular in outline, the apex of the triangle having attached to it in the male the conspicuous lozenge-shaped third genital segment, and in the female, being conical. The abdomen rarely reaches backwards much beyond the trochanters of the hind legs. Including the genital seements, the abdomen consists of nine segments, of which the first three are covered above by the metanotum, and the last three are the genital segments. The Abdomen of the Male. Dorsal Surface.—(P1. I. fig. 8,¢ 8). The hind margins of the first two (covered) segments, when they can be traced across, are rather strongly concave, or even some- times slightly angulated; the hind margin of the third segment (coinciding with the hind margin of the metanotum) is less concave, or sometimes nearly straight. These three segments are longer in the middle than at the sides. Occasionally the suture be- tween the second and third segments can be traced across the side plate (pleuron) men- tioned in the description of the thorax. In most species the division between the third and fourth segments is well defined on this plate. The fourth seement (the first free one) is usually the longest of the free segments, the remaining two being rather shorter and subequal in length to each other. At the sides of the basal segments there are sometimes slight indications of a connexivum (pleuron), but owing to the position of the abdomen this is very inconspicuous and obscure. The genital seoments will be described separately. Ventral Surface.—(PI. I. fig. 8, 2 ab.b.). All the six abdominal segments are uncovered. The first five are very. short, ring-like, subequal in length, and more or less retracted within each other. The first is more or less covered at the sides by the mesosternum. 32 THE VOYAGE OF H.M.S8. CHALLENGER. On the middle of it is a tubercle whose apex looks backwards and downwards, and is pierced by a somewhat transverse perforation. All the species, and both sexes, are fur- nished with this tubercle, though in some specimens it is scarcely visible, from the seg- ment being retracted below the mesosternum. What may be the nature of this tubercle, and its use, must remain uncertain until ob- servations have been made on the living animal. There is nothing, so far as I am aware, corresponding to it in any other true insect. It is possible that its homologies may be found in the “ventral tube” of the Collembola. If such be the case the use may be to secure attachment to the animals on whose juices Halobates doubtless feeds, but it 1s some- what idle to speculate on the origin and use till actual observations have thrown some light on the nature of the organ. (See note in the Appendix.) The sixth segment is longer (sometimes much longer) than the others, and the sides are produced obliquely backwards to clasp the sides of the first genital segment. In all the segments the hind margins on the ventral surface are nearer the base of the abdomen than the hind margins on the dorsal surface. The Abdomen of the Female. On the dorsal surface it is, on the whole, similar to the male abdomen, with the exception of the differences in the structure of the pleuron mentioned in the description of the thorax. On the ventral surface (Pl. I. fig. 7 2 ab. b.) all the six segments are ring-like. The sixth is prolonged a little at the sides. The first segment is furnished with a tubercle as in the male. : The Genital Segments of the Male. The First Segment is, on the dorsal surface, ring-like, and similar to the last abdominal segment, but not so broad. Below it is nearly as long as (or even sometimes longer than) the whole of the abdominal segments taken together, while in shape it is trans- versely oblong or nearly square. The Second Segment is almost hidden, both above and below, by the first, the only parts usually visible being a small, crescent-shaped, or semilunar plate above, while be- low all that can be seen is a long horn-like process on each side. On dissection the true form of the segment is seen to be as follows :— Above (PL III. figs. 20 and 21), transversely oblong, about four times as broad as long ; hind margin much prolonged in the middle, the prolongation (the apex of which is the only part visible without dissection) presenting a rounded outline posteriorly. Below, the middle of the hind margin is concave, giving rise near each side to a long horn-like process which les along the side of the next segment, and reaches to or beyond REPORT ON THE PELAGIC HEMIPTERA. 315: the middle of its length (PI. III. fig. 22). These processes differ in shape in different species, but deficiency of material to dissect has prevented me from describing them minutely in more than two species (PI. IIL figs. 23 and 24). It may be noted that in one species the left horn is always bent outwards and forwards (Pl. IL. fig. 22); in all the other species examined by me both horns are symmetrical. The posterior angles of the segment are in some species furnished with a tubercle-like prolongation; in others this prolongation is situated between the angle and the base of the horn. The Third Segment.—Ahove, the visible part of this is very conspicuous as an appendage to the end of the abdomen, in outline somewhat like the fluke of an anchor, with the lateral angles more or less produced and the general shape varying according to the species (PI. IIT. figs. 20 and 25). The disk is longitudinally convexly elevated from the base (which is sometimes sh¢htly gibbous) to the obtusely conical apex. The sides are some- what flat, or even shehtly depressed. The apex of the segment, viewed from above or from below, looks like an obtusely conical tubercle (PL. IIL. figs. 25 and 26 ; and PL. I. fig. 1,9 a), but closer examination shows that the lower half of itis a nearly circular very convex plate, attached by the basal angles to the plate above. Between these plates is a horizontal fissure (at the very apex of the abdomen), in which the intestinal canal opens. The plates are therefore the podical plates. On dissection, the under surface of the upper or lozenge- shaped plate shows a deep longitudinal hollow, in which the intestine les (PI. III. fig. 26). The under surface of the extended sides is sometimes armed with short spines. The third segment below is not continuous at the sides with the third segment above, and in its normal condition (that is, without having been dissected out) appears as a long, oval, convex plate, overlapped at the sides and end by the upper plate, and additionally protected at the sides by the horns of the second segment (PI. I. fig. 1, ga). In some species the margin appears to be a little thickened, and to forma ledge on which the horns rest. On dissection, the plate presents internally (Pl. III. fig. 27) a deep concavity, filled by the horny case which contains the copulatory apparatus. The basal angles are expanded and go upwards and inwards to meet the base of the lozenge-shaped plate whose attachment is between them, the point of attachment being concealed by the pro- duced hind margin of the second segment. The horny capsule (Pl. IL. fig. 28) just referred to is, viewed from above, very convex, rather strongly compressed laterally, and with a very polished surface. Dissected out and viewed from the side, it is seen to be a semicircular case, with the sides somewhat flattened, and the opening on the straighter margin of the semicircle. This straighter margin is not exactly straight, but, so far as the chitinous portion of it is concerned, is for the basal third straight, then widely concave, and then, for about the apical fourth, gently rounded. Along the straight and concave portions of the margin are (in the dissection) the remains of the membrane by which the capsule is attached, the apical fourth being free. It is difficult to make out and to describe the structure of the apparatus contained in the (ZOOL, CHALL, EXP.—PART XIX.—1883.) T5 34 THE VOYAGE OF H.M.S. CHALLENGER. capsule. From the apex often protrudes a long, very narrow, gradually attenuating process, which, when not protruded, is curled up within the capsule. In wiillerstorfji the capsule is about *52 mm. long by *3 mm. broad, and the process, so far as protruded, nearly 1 mm. inlength. In seviceus the capsule is rather smaller. The Genital Segments of the Female. Above and below, three segments are visible. - The first is, above, like the preceding abdominal segment, but not so broad. Below it is much longer than it is above, and subequal in length to three or more of the abdominal ventral segments. In shape it is transversely oblong. On the lateral line the dorsal and ventral parts of the plate are posteriorly not continuous for a greater or less length. In dissected examples may be seen a long process (triangular at the base), extending from the front margin forwards within the sixth and fifth abdominal segments. The second segment is, above, similar to the first, but rather shorter and much narrower. Below, it consists of two triangular plates, whose edges meet or overlap in the longitudinal mesial line (PI. I. fig. 7, 2 ab. b.). (In some cases the first genital segment more or less completely covers the second below.) Within the genital fissure thus formed, bat usually quite concealed, is situated the ovipositor, &c. The ovipositor appears to con- sist of four valves. Two, which le somewhat externally to the other two, are sublanceo- late in shape, with the inner apical margin slightly recurved upwards and outwards, and fringed with long hairs. The two inner valves are rather shorter and narrowly lanceolate, with their inner edges also fringed with long hairs, The third segment terminates the body, and is altogether, in form and structure, like the conical apex of the abdomen of the male. THE Legs. The Front Legs. These are very short in comparison with the others, but are relatively stouter. In addition to subserving locomotion, they are (without being raptorial) fitted for grasping, and, for the greater part of their length, lie well in advance of the body. The Acetabula have been already described. The Coxa (PI, I. fig. 8, ac.) is stout, and for the most part immersed in the acetabulum. It can best be seen on the inner side, where it presents a somewhat triangular outline. In colour it is usually somewhat paler than the rest of the lee. The Trochanter (Pl. I. fig. 8, ac.) is large, about twice as long as broad, narrow at the base, and increasing gradually in breadth upwards. It is curved abruptly at the base, and the broad apex is cut obliquely forwards to articulate with the femur. The Femur is joined to the anterior apical face of the trochanter, the base being REPORT ON THE PELAGIC HEMIPTERA. 35 curved somewhat downwards and backwards, It is usually stout, but varies in stoutness and shape in different species. The greatest thickness is usually a little above the base, and it is gradually attenuated upwards from about the middle. The anterior edge is nearly straight from the bend at the base to beyond the middle, and thence slightly curved convexly to the apex. The basal half of the posterior edge is either subparallel to the anterior edge or slightly convex, while the apical half is more or less (varying in different species) strongly curved concavely. Near the apex on the posterior edge is a notch, often nearly obsolete, but whose position is then marked in microscopical specimens by a thickening of the integument. The apex itself, which is sometimes very slightly incrassate, presents, when viewed from above (that is, between the anterior and posterior edges), an irregularly oblique outline; nearest the anterior edge it is straight, followed by a semicircular notch, and thence to the hind margin obliquely concave. The femur is more or less pubescent, the hairs on the lower posterior side being more numerous and longer, especially towards the base. The margin of the apex is fringed with long hairs. In most, if not in all the species, the femur is armed with a series of five or more long black hair-hke spines, not quite erect, but pointing down the limb, and inserted a little above the posterior edge. The spines are longest and strongest near the base, and the series is not in all cases continued to the apex. The Tibia is usually a little shorter than the femur, and much less stout. For the ereater part of its length it is of equal thickness, but the extreme base is narrower, and the apex dilated and bifurcate. The upper branch of the bifurcation is a continuation of the long axis of the tibia, while the lower and posterior branch is subtriangular in outline, the basal side being curved, and the apical side slightly angular and at right angles to the anterior branch. The dilated portion varies in size and shape in different species, On the under side the anterior branch is somewhat flattened, and between it and the posterior branch is an oblique furrow. To the apex of the anterior branch, which is obtusely angular, the tarsus is articulated. On the outer side of the apex of the other branch is an oval patch (varying in size and shape in different species) of peculiar hairs. (Pl. IL figs. 9 and 10). These hairs are very short (in wiillerstorffi_ about ‘025 mm., and in sericeus about ‘024 mm. long), set so close together that they touch each other at the base and for some distance above it, and are gradually narrowed upwards to the rather blunt apex (PI. III. fig. 11). The patch is to be found only in the male; in the female, at the same spot, is a small tuft of short, almost straight hairs, not so closely set together. The tibia is more or less pubescent, the pubescence being stronger and thicker on the under side of the dilated portion. The tibia is also armed with a series of spines similar to those of the femur, but less strong, and inserted a little below the posterior edge. The Tarsus is two-jointed, and usually a little shorter than the tibia, and rather less stout. 36 THE VOYAGE OF H.M.S. CHALLENGER. The relative length of the joints one to the other varies in the different species, and often affords a good point of distinction. The first joint may be equal to, or longer, or shorter than the second. In form it is cylindrical, and the base has a narrow neck. The outer side is clothed with strong hairs, which spring, as in other parts of the leg, from flat circular tubercles. On the inner side some of the hairs are arranged in a regular series, and the general pubescence is finer. The second joint has also a neck at base, above which it is cylindrical, and with pubescence similar to that of the first joint. At about the middle of its length the joint is cleft longitudinally into two unequal parts (Pl. ILI. fig. 13). The upper and outer part (which may be looked upon as the joint itself, while the lower and inner part may be called a process) is twice or three times the leneth of the other part, but is only about half as thick as the basal half of the joint. On the outer side it is rounded, but on the side facing the process it is flat or slightly channeled, and destitute of pubescence. The hairs on the outer side are rather coarse and adpressed, but towards the apex a few stronger, less adpressed hairs are mixed with the others, and in some species at least two or three long stout hairs, with curved extremities arise some way before the apex, and reach to or beyond it. The process, or shorter part of the cleft jomt, is parallel to the other part. It is somewhat triangular in outline, with a blunt apex, the outer side rounded and clothed with rather long semi-adpressed hairs; the inner face furrowed and destitute of pubescence. The fissure between the two parts is wider on the under side of the joint than on the upper. At the bottom of the cleft are inserted the two curved sharp pointed claws (PI. IIL fiz. 14), which are about double the length of the shorter division or process of the joint. Each claw is rather broad, somewhat angularly keeled on the posterior surface, and slightly concave on the other. At the base it is suddenly dilated posteriorly, the dilatation being triangular in outline. In one species (wiillerstorffi) the claws are about *23 mm. long, ‘in another (sericeus), they are about "17 mm. From between and a little behind the claws arises a thin ribbon-like process about as long, but only half as broad, as the claws, curved backwards, equally wide and thin throughout, and truncate at the apex (Pl. II. figs. 13 and 14). The use of this process is unknown. The Middle Legs. The Acetabulum has been already described. The Coxa is cylindrical, much broader than long; the apex is truncate, and fringed with rather long hairs, which curve inwards ; it is hollowed to receive the expanded base of the trochanter. The Trochanter (P1. III. fig. 15, tv.) is about three times as long as broad. Its base is a somewhat flattened ball, which fits into the hollowed apex of the coxa. Above the REPORT ON THE PELAGIC HEMIPTERA. 37 base is a very short neck, above which the trochanter suddenly widens, and curves upwards and inwards; it is then for half the length somewhat cylindrical, while the apical half narrows to a point above, and below is triangularly cleft to receive the femur. The trochanter is more or less pubescent, and is sometimes armed on the inner side with small teeth or spines. The Femur (Pl. IIL. fig. 15, f) is much the longest joint. It is somewhat incrassate at the base, and becomes gradually thinner to about the middle, after which it is for a little way of equal thickness, and then is gradually and slightly incrassated to the apex. It is more or less pubescent, and is usually armed with small spines or teeth pointing backwards, and arranged in a series on the inner side from base to apex; more rarely the spines are irregularly scattered. The Tibia (PLU. figs. 15 and 16, #7.) is shorter and less stout than the femur, cylindrical, and slightly and gradually attenuate from base to apex. It may be armed like the femur, or be unarmed. On the inner edge is one or more series of flattened circular tubercles, from which arise hairs (usually more or less curved at the apex), increasing in number and length towards the apex of the joint. From out of this line of curved hairs springs a fringe of very long hairs, many times longer than the diameter of the tibia, and naturally straight but easily bent. Atthe base of the joint these hairs are few, but their number and their length increase towards the apex. The Tarsus (Pl. II. figs. 15 and 16, ta.) is two-jointed, the first joint being longer than the second, but varying in its relative length in the different species. The first joint (Pl. III. fig. 16, ta. 1) is cylindrical, and a little incrassate at the base. Its inner edge is furnished with hairs similar to those on the inner edge of the tibia; towards the apex of the joimt these hairs diminish in leneth (Pl. IL -fig. 17). Approximate measurements of this joint (taken about the middle) give (in wiillerstorffi) the diameter of the joint ‘08 mm. ; length ofthe hairs on the inner side 035 mm.; of the curved short fringe (05 mm.; and of the long fringe *4 mm. In sericews the corresponding measure- ments are ‘05 mm.; 025 mm.; ‘05 mm. and ‘4 mm. The second joint (PI. III. figs. 15 and 16, ta. 2) is cylindrical, and bears on its inner side a line of short curved hairs, similar to that on the first jomt, but without the long hairs. Not far from the apex on the inner side is a notch or excavation, from which to the apex runs a furrow, in which lie two straight claws. Arising from between the claws is a ribbon-like process similar to that on the front tarsus. Between the notch and the apex the joint is thinner than before the notch, and on its outer side arises, some way before the tip, one or two long stout hairs, more or less abruptly bent at the apex, and extending beyond the end of the joint. The length of the claws is, in wiillerstorffi, about 085 mm., and of the longest hair on the opposite side of the joint ‘2 mm. (the ordinary hairs there being ‘05 mm.). In sericeus the claws are ‘08 mm. long. 38 ‘THE VOYAGE OF H.M.S. CHALLENGER. The Hind Legs. In general form these resemble the middle legs, but are somewhat shorter and less stout. The Acetabulum has been already described. The Coxa is three or more times as long as broad, slightly curved outwards, and slightly incrassate at the apex. The Trochanter is shorter and thinner than the middle trochanter. - The Femur shorter and thinner than the middle femur. The Tibia has not the fringe of hairs on the inner side. The Tarsus (Pl. ILL. figs. 18 and 19) is one-jointed. The joint is similar to the second joint of the middle legs, but has not the frmge of hairs on the inner side, and the excava- tion for the claws israther more distant from the tip. Like the middle tarsus there is, on the side of the joint opposite to the claws, one to three long hairs inserted at different places, and reaching to or beyond the apex of the jomt. The ribbon-like process from between the claws is also present. The claws measure in wiillerstorffi about ‘15 mm., and in sericeus *12 mm. RESPIRATORY SYSTEM. As in most other insects, air is admitted to the tracheal system by means of spiracles. I have failed to find any trace of prothoracic spiracles. The large mesothoracic spiracles have already been noticed (p, 30). The remaining spiracles are nearly circular in outline, and the first pair of these are inserted near the posterior end of the thorax (though possibly abdominal), and more or less near the sides of the body is one pair, and in the abdomen six pairs can without much difficulty be made out; and possibly others may exist, but may be concealed by the legs. Those that can be seen are as follows :—One pair on the first segment, usually covered by the thorax ; one pair on each of the last three segments situated nearer the side of the body than those on the first segment; one pair on the first genital segment ; and one pair on the second genital segment, situated at the posterior angles in the male, and about the middle of the side in the female. Measurements of the various circular spiracles give an average of, in wiillerstorffi, ‘035, and im sericeus, 025 mm. for the long diameter. In the last two segments of the larva no spiracles exist. I regret very much that want of material has prevented me from examining the internal anatomy more completely. REPORT ON THE PELAGIC HEMIPTERA. 39 DESCRIPTION OF THE SPECIES. The number of species of Halobates (in the restricted sense) already described is five, viz. FHalobates micans, Esch. 5 sericeus, Esch. » flaviventris, Esch. 5 streatfieldanus, Temp). “ wiillerstor ffi, Frauent. To these I am able to add six, namely :— bo 10 Halobates princeps. Halobates germanus. hayanus. 3 sobrinus. 29 i proavus. - Srauenfeldanus. KEY TO THE SPECIES.1 The last three joints of the autennz of equal length, : : . fravenfeldanus. The last three joints not all of equal length, 2 Front femora more or less distinctly steel-blue in colour, 3 Front femora not blue, : F F . Antenne with the second and third joints equally long, . : 5 . micans. Antenne with the second joint one-fourth longer than the third joint, . wiillerstorffi. Front tarsus with the first joint nearly twice as long as the second joint, . princeps. Front tarsus with the first joint never more than equal in leneth to the second joint, 5 Antenne with second joint equal to, or a little longer than, the fourth joint, : 6 Antenne with the second joint distinctly shorter than the fourth joint, . ; 8 Front tarsus with the first joint almost as long as the second, ; : flaviventris, Front tarsus with the first joint distinctly shorter than the second joint, . : 7 Front tarsus with the first joint one-half shorter than the second joint; antenne with the second and fourth joints subequal in length, . : ; hayanus Front tarsus with the first joint one-third shorter than the second ; antenn with the second joint rather longer than the fourth joint, . : : proavus. Front tarsus with the joints subequal in length, . : : . streatfieldanus. Front tarsus with the first joint shorter than the second joint, : : : 9 Middle tarsus with the first joint seven times longer than the second joint, . sericeus. Middle tarsus with the first joint not more than five times longer than the second joint, 10 Base of antennie narrowly rufous ochreous; front tarsus with first joint a little more than half the length of the second joint, 3 : : germanus. Base of antennz concolourous ; front tarsus joint about one-fourth shorter than the second joint, sobrinus. 1 The “key” must be used with caution More than one or two points have to be taken into consideration in dis- criminating the more closely allied species. 40 THE VOYAGE OF H.M.S. CHALLENGER. 1. Halobates wiillerstorgi, Frauenf. (Pl. 1. fig. 1). Halobates wiillerstorfi, Frauenfeld, Verbandl. der. k. k. zool. bot. Gesellschaft in Wien, Band xvii. p. 458, Taf. xii. figs. 1, 2, 6, 8, and 10, 1867. Oval, widest behind the middle. Whitish ash grey, paler on the sides and below. Back of the head with two very indistinct reddish spots. First two joints of the antennze (indistinctly), coxee, trochanters, and femora, and in a less degree the tibize more or less shining steely blue. Second joint of antennz nearly one-fourth shorter than the fourth, and about one-fourth longer than the third. Front tarsus with first joint rather shorter than the second. Middle tarsus first joint more than three and a half times the length of the second. ¢. Length 4°25, breadth 2°3, middle femur 5, hind femur 3°25 mm. ?. Length 3°5, breadth 2°5, middle femur 4, hind femur 2°5 mm. Habitat.—The most widely diffused of all the species, but most common in the North Atlantic, between the tropic of Cancer and the equator. Less common in the North Atlantic, north of the tropics ; in the South Atlantic, within the tropics; in the Indian Ocean ; in the North-West Pacific, at about lat. 10° N., and in the South Pacific at about the tropic. There are no records of its occurrence in the Eastern Pacific. In the Atlantic specimens have been taken between about lat. 43° N. and 20°S. In the Pacific between about lat. 10° N. and 25° 8. In the Pacific specimens have not been taken east of long, 175° E. x The following are the localities of the specimens seen by me :— Challenger Specimens. North Atlantic, localities :—Station 98, Aug. 14, 1873, lat. 9° 21’ N., long. 18° 28’ W.; between Teneriffe and St. Thomas, West Indies, February and March 1873; about lat. 18° N., long. 28° W., April 28, 1876; Station 62, June 18, 1873, lat. 35° 7’ N., long. 52° 32’ W. South Atlantic :—Off Rio de Janeiro, June 18, 1873. North Pacific :—North of the Admiralty Islands, March 1875 (about lat. 12° N., long. 142° E.). Specimens from other Sources. North Atlantic localities :—Cape Finisterre (Oxford Museum) ; lat. 10° N. (Stockholin Museum) ; lat. 9° 20’ N.—5° N., long. 26° 30’ W.—26° 50’ W. (Liverpool Museum) ; Sargasso Sea (Liverpool Museum) ; lat. 5° N., long. 25° W. (Liverpool Musewm) ; lat. 2° 30’ N., long. 28° 30’ W., January 31, 1865 (Liverpool Museum); Atlantic near equator (Stockholm Museum). © South Atlantic localities :—Near St. Helena (Berlin Museum) ; South Atlantic (Liver- pool Museum). REPORT ON THE PELAGIC HEMIPTERA. 41 Indian Ocean localities :—Just south of Mauritius, lat. 25° 8. (Collingwood) ; Sunda Straits (Turin Museum) ; lat. 2° 8., long. 84° 20’ E. ( Westwood). Pacific localities :—Near Norfolk Island (Berlin Museum) ; Guinea (Signoret). d. Oval, widest before the middle (Pl. I. fig. 12). Whitish ash grey, paler on the sides and below; sometimes with slightly brassy reflections. The two reddish spots at the back of the head more or less ill-defined. Eyes dark brown. Rostrum shining black, apex fulvous brown. Claws of the legs fulvous brown. Antenne black, with, especially on the last two joints, greyish pubescence ; the first two joints with an indistinct bluish tinge. Legs black ; coxze, trochanters, and femora, especially of the middle and hind legs, and ina less degree the tibice, more or less shining steel-blue. Front legs with grey hairs, the other legs with black or dark grey hairs. Underside of abdomen towards the middle at the sides more or less indistinctly reddish ochreous. Genital segments more or less shining bluish-black, but usually covered with greyish pubescence which is easily denuded. Head rather strongly convex, slightly elevated on the mesial longitudinal line. Antenne (PL I. fig. 1, a.) three-fifths the length of the body ; first joint rather shorter than the other three taken together, slightly curved, very slightly thinner upwards, and apex slightly incrassate ; second joint almost one-third the length of the first, slender, thinnest in the middle, then slightly incrassate to apex; third joint rather stout, cylindrical, thickest towards the apex, about three-fourths the length of the second; fourth joint nearly one-fourth longer than the second, thickest at the base, then gradually and slightly attenuate upwards. Pronotum with front and hind margins nearly equally concave ; disk slightly convex, with two transverse foveze on each side, of which the posterior are the largest. Mesono- tum widest about the middle, disk very convex. Front Legs: Femora stout, thickest near the base, thence equally thick to. the middle, and then slightly and gradually attenuate to the apex ; slightly notched on the inner side just before the apex. The usual hairlike spines are frequently absent. Tibia nearly four- fifths the leneth of the femur, apex strongly dilated. Tarsus (PI. I. fig. 1, ft.) about four- fifths the length of the tibia ; second joint longer than the first, cleft about the middle. Middle Legs: Femora about one-eighth shorter than the tibia and tarsus taken to- gether ; scarcely incrassate at the apex, and rarely and obscurely armed with spines. Tibia (PI. I. fig. 1, m.t.) rather more than one-half the length of the femur, rarely and obscurely armed. Tarsus subequal to, or slightly shorter than, the tibia, the first joint more than three and a half times the length of the second. Hind Legs: Femur subequal in length to the tibia and tarsus taken together, rarely and obscurely armed with spines. Tibia about one-fourth shorter than the femur. Tarsus more than one-fourth the length of the tibia, cleft at about two-thirds the length from the base. (ZOOL. CHALL, EXP,—PaRT xIx,—1883.) T6 42 THE VOYAGE OF H.M.S. CHALLENGER. Abdomen: Sixth ventral segment nearly as long as the other five, the disk rather flatly depressed posteriorly. Genital Segments: First below nearly as long as all the abdominal segments taken together, nearly as long as broad, hind margin straight, posterior angles rounded. Second below only visible at the sides; the right horn reaching nearly to the apex of the next seoment (below); the left horn bent just above the base, and directed outwards and a little upwards (PI. II. fig. 22). The horns (Pl. II. fig. 23) have thickened margins; the outer margin and the surface generally are covered with slight tubercles tipped with hairs ; the apical margin is smooth; the inner is fringed at the base with long hairs, and from near the base to the apex is armed with tubercle-like teeth, arranged in several series on the thickened part, and pointing downwards. The hairs on the surface also point down- wards. The posterior angles of this segment are prolonged into a broad tubercle-like process. The third segment above (PI. I. fig. 1 g, and 1 ga) has the lateral angles some- what produced.*| The third seement below has apparently thickened margins. ?. (PI. I. fig. 1,2.) Similar in appearance to the male, but differs in the following particulars :-— Form more widely oval ; femora of front legs and first joint of antennee more distinctly steel-blue. Front femora less stout. Hind margins of ventral segments and apex of third genital segment indistinctly brownish-red. Below, the first genital segment about covers the second. Halobates wiillerstorfi has been found from January to April, from June to August, and in October, and the larvee from January to April, so that it probably occurs through- out the whole year. The only note that I can find regarding the life history is in Dr. Cuthbert Colling- wood’s Rambles of a Naturalist, p. 358. The specimens referred to were given by him to Mr. J. W. Douglas, and by Mr. Douglas to me, and appertain to this species. “ A notable circumstance occurred in the Indian Ocean, in lat. 25° S., just south of the Mauri- tius. For several days in succession the net produced Halobates, glass-crabs, Velelle, and the beautiful oceanic shell Janthina, of a rich deep violet colour.” A footnote is added as follows :—* The occurrence of this singular Hemipterous insect at sea is at least very remarkable. There appear to be several species, of which I met with two, one on the coast of China, and the other some 500 miles from the land, in the South Indian Ocean. That they are veritable marine insects I think cannot admit of a doubt, though how they exist in the open ocean is a mystery. They are of a deep bluish-black, with six legs, the two hindermost furnished with a delicate brush on the inner side of the tarsus. The abdomen is remarkably undeveloped. Although taken occasionally in the ’ For the form of this segment in the present and succeeding species, the student is referred to the figures, which will give a much better idea of the shape than any description could do. REPORT ON THE PELAGIC HEMIPTERA. 43 towing-net, I did not find them common, and never observed any movement after capture, owing to their delicate soft bodies being injured by the passage of water and other things through the net.” 2. Halobates macans, Esch. (PI. I. fig. 2). Halobates micans, Esch., Entomographien, i. p. 107, No. 78), Taf. i. fig. 3, 1822. Burmeister, Handbuch der Entomologie, vol. ii. p. 208, No. 1, 1835. Blanchard, Hist. Natur, des Insectes, vol. iii. p. 98, No. 1, 1840. Herrich-Schiiffer, Die wanzenartigen Insecten, vol. viii. p. 110, 1848. Frauenfeld, Verhandl. der k. k, zool. bot. Gesellsch. in Wien, p. 458, Taf. xii. fig. 5, 1867. Widely oval, widest behind the middle. Hoary ash grey, hghter below. Antenne and legs black, front femora bluish. Antennze with second and third joints equal in length. 9. Length 4, breadth 2°25, middle femur 4°6 mm. Habitat.—Reported by Eschscholtz from the South Pacific and South Atlantic Oceans, and by Frauenfeld from the Indian Ocean, near Ceylon (lat. 3° N.). I have not seen this species, and the above diagnosis and the following description are drawn up from the writings of Eschscholtz and Frauenfeld. Both these writers say that they have seen males only, but they confused the sexes—Eschscholtz’s figure re- presenting a female. ?. Closely allied to Halobates wiillerstorffi. Widely oval or conical. Hoary ash grey or blackish-grey, somewhat shining, brighter coloured below. With (according to Eschscholtz) brassy reflections, which, however, Frauenfeld denies. Eyes black. An- tenne and legs black, the front femora bluish. Abdomen whitish-grey. Antennze (Pl. L. fig. 2, a.) rather slender, rather longer than half the body, first jomt as long as the other three together ; second and third equal in length; fourth jomt longer than the third. Pronotum strongly concave in front, nearly straight behind; disk with two rather long foveze anteriorly. Mesonotum strongly convex anteriorly. According to Frauenfeld, micans differs from wiillerstorfi in the slenderer antenne, with longer first joint, and second and third joints equal in length; legs more slender, and, except the front femora, without any bluish tinge. Dr. Rogenhofer kindly measured, at my request, some of Frauenfeld’s specimens in the Vienna Museum, and states the proportions of the joints of the tarsi to be as follows : —First joint of front tarsus very little shorter than the second joint ; middle tarsus one- sixth shorter than the middle tibia ; first joint of middle tarsus less than three times the length of the second. As Frauenfeld was acquainted with both species, there can be no doubt that micans exists as a species distinct from wiillerstorgi, but whether all the specimens that 44 THE VOYAGE OF H.M.S. CHALLENGER. Eschscholtz saw, and on the strength of which he gives as localities the South Atlantic and South Pacific Oceans, are really referable to micans, seems to me open to doubt. 3. Halobates princeps, n. sp. (Pl. I. fig. 3). Oblong oval, widest behind the middle. Somewhat shining, silvery ash grey, espe- cially on the sides and below. A reddish-yellow oblique mark on each side of the head posteriorly. Middle acetabula, with the inferior margins, inner edge of suture, and the adjacent part of the hind margin of mesosternum, as well as the hind margins of the ventral segments, fuscous ochreous. Antennze and front legs black. Middle and hind legs brownish-black. Antenne with second joimt subequal in length to fourth, less than twice as long as third. Front tarsus with first joint a little less than twice as long as second. Middle tarsus with first joint more than three and a half times the length of second. @?. Length 5°5, breadth 2°3, middle femur 7, hind femur 5 mm. Habitat.—Celebes Sea. February 6th, 1875. One specimen. (Challenger.) Somewhat like Halobates wiillerstorgi, but distmeuished from that and other species by its larger size and longer middle and hind legs, as well as by the long first joint of the middle tarsus. ?. Oblong oval, widest behind the middle. Slightly shining silvery ash grey, brighter at the sides and below. Back of the head with an oblique, not very well-defined reddish-yellow spot on each side. Antenne and front legs black, with greyish pubes- cence, The other legs brownish-black ; coxee and trochanters with silvery grey hairs, the other joints with fuscous hairs. Eyes brown. Rostrum black. Margins of the middle acetabula below, the adjacent part of the hind margin of the mesosternum, the inner edge of the middle acetabular suture, and the hind margins of the ventral abdominal segments fuscous ochreous. Antenne (Pl. IL. fig. 8, a.) about three-fourths the length of the body; first joint slender, subequal in leneth to the other three joints taken together; second joint slender, about one-third the length of the first ; third joint more than one-half the length of the second ; fourth subequal in length to second, stout and slightly attenuate upwards, Pronotum with front margin strongly and hind margin slightly concave ; disk with a wide transverse fovea on each side anteriorly. Mesonotum widest behind the middle. Front legs with stout femora, thickest about the middle ; tibia subequal in length to femur; tarsus (Pl. I. fig. 3, ft.) subequal in length to the tibia, first joint a little less than twice as long as the second, which is cleft between the base and the middle. REPORT ON THE PELAGIC HEMIPTERA. 45 Middle legs: trochanter armed with spines; femora as long as the tibia and tarsus taken together, armed with very fine spines; tibia more than one-half the length of the femur, the basal one-third armed with fine spines; tarsus (Pl. I. fig. 3, m.t.) one-fifth shorter than the tibia, first joint more than three and a half times the length of the second. Hind legs: femur, about two-thirds the length of the middle femur, one-fifth longer than the tibia and tarsus taken together, armed with fine spines ; tibia about half as long as the femur, armed with fine spines; tarsus about five-eighths of the length of the tibia, cleft a little beyond the middle. Abdomen: fourth dorsal segment with two obscure short transverse impressions on each side of the middle. Genital segments: first below longer than all the ventral abdominal segments taken together, strongly transversely convex, hind margin straight. Second segment below concealed by the first. 4. Halobates streatfieldanus, Templn. (PI. I. fig. 4). Halobates streatfieldana, Templeton, Trans. Entom. Soc, of London, vol. i. p. 230, pl. xxii. fig. A, 1836. Broadly ovate, widest behind the middle. Brilliant black above, brownish-black below. Two small spots at the back of the head, and the sides and hind margins of the fourth and fifth abdominal seements above rufous. Abdomen below with the first five segments yellowish, with hind margins rufous. Antennz: second joint longer than the third, but shorter than the fourth. Front tarsus with the joints subequal in length. ?. Length, 0°13 inch (3°3 mm.). Habitat.—Atlantic Ocean, nearly midway between Africa and America south of the equator. I have not seen this species. The above diagnosis and the following description are compiled from Templeton’s paper. ?. Broadly ovate or lozenge-shaped. Brilliant black above, brownish-black below ; sides when dry somewhat hoary. Head with a rufous spot on each side of the middle at the hind margin. Eyes rufous. Abdomen above with the sides and hind margins of the fourth and fifth segments rufous; below with the first five segments yellowish, with rufous hind margins. Antenne (PI. I. fig. 4, a.) about two-thirds the length of the body ; first joimt slender, not so long as the other three taken together; second longer than the third; fourth longer than the second, attenuating upwards. 46 THE VOYAGE OF H.M.S. CHALLENGER. Pronotum gently channeled into three subequal divisions, scarcely visible in the dried specimen. Front legs (Pl. I. fig. 4, fl.) : tarsus (Pl. I. fig. 4, £¢.) with the joints subequal, the second cleft about the middle. Templeton’s full description, as also the account of the capture of the specimen, will be found in the first part of this paper. 5. Halobates sobrinus, n. sp. (Pl. I. fig. 5). Long oval, widest behind middle (2), or oval, widest about the middle (¢). Ashy orey (3g), or dark grey (2), paler below. Head with two ill-defined rufous spots pos- teriorly. Antennze and legs dull fuscous black. Abdomen: hind margin of fourth dorsal seoment rusty brown, genital segments dull fuscous black (¢); or ventral segments dull brownish, hind margins broadly ochreous, first and second genital segments brownish below, middle acetabula below from the suture inwardly rather broadly ochreous ( ¢ ). Antenne: third joint rather more than one-fourth shorter than the second, which is one- fourth shorter than the fourth. Front tarsus: first jomt about one-quarter of the length shorter than the second. Middle tarsus: second joint rather more than one-quarter of the length of first. g. Length 4, breadth 1°75, middle femur 5, hind femur 4°5 mm. ?. Length 4, breadth 2, middle femur 4, hind femur 3 mm. Habitat.—Tahiti (Stockholm Museum). g¢. Long oval, widest behind the middle. Ashy grey, somewhat paler below. Head with the usual ill-defined rufous spots. Antenne, legs, first genital segment below, and genital segments above, dull fuscous black, with more or less sparse grey pubescence. Head with the hind margin very slightly elevated on each side of the middle. Antenne (P1. I. fig. 5, a.) about three-fifths the length of the body; first joint shorter than the other three taken together ; second joint about one-half the length of the first ; third about three-quarters the leneth of the second ; fourth about one-quarter longer than the second, attenuate from the middle upwards. Pronotum: front margin rather strongly concave, hind margin slightly concave ; disk shghtly convex, with a very fine impressed longitudial central line, on each side of which is an anterior transverse fovea. Mesonotwm gradually widened to beyond middle, disk convex, with a very fine percurrent longitudinal central line. Front legs: femora rather stout; tibia subequal in length to femur; tarsus (PL I. fig. 5, ft.) about two-thirds as long as tibia, first joint about one-fourth shorter than the second, which is cleft before the middle. REPORT ON THE PELAGIC HEMIPTERA. 47 Middle legs: femur subequal in length to tibia and tarsus together, armed with a series of small teeth, as is the tibia; tibia about three-fourths of the femur in length ; tarsus (PL. I. fig. 5, m.t.) about three-fourths of the tibia in length, second joint rather longer than one-fourth of the first, cleft near apex. Hind legs: femur and tibia armed like the middle legs, the femur about one-third longer than the tibia and tarsus taken together; tarsus about one-third the length of the tibia, cleft beyond the middle. Abdomen (which appears to be a little distorted—in drying—in the specimen described) with the sixth ventral segment a little longer than the fifth. Genital segments: first below subequal in length to all the abdominal ventral seements, hind margin very slightly concave, sides oblique. Second segment with horns reaching nearly to the apex of third below: exterior to the base of each horn is a spine- like tubercle. Third segment (PIL. I. fig. 5, g.) above with the lateral angles much pro- duced outwardly. @. Oval, broadest about the middle. Darker in colour than the male; middle aceta- bula below, from the suture inwardly, rather broadly ochreous, shading into brown. Abdomen above with the hind margins of the uncovered segments, especially the fourth and fifth, rusty brown (possibly, however, this is the membrane between the segments, more visible than usual); ventral segments (2nd to 6th) dull brown, with the hind margins broadly ochreous. Genital segments: first fuscous brown; second below brown; third below black. Head more convex than in male, the hind margin not elevated. Antenne with the fourth joint quite as long as half the first, and about one-fourth longer than the second. Abdomen: hind margins of ventral segments rather elevated and thickened. It is not improbable that fresher examples of this species may be greyer in general colour. 6. Halobates sericeus, Esch, (PI. I. fig. 7). fHalobates sericeus, Esch., Entomographien, i. p. 108, No. 79, Taf. ii. fig. 4, 1822. 3urmeister, Handb. d. Entomol. ii. p. 209, No. 2, 1835. Blanchard, Hist. Nat., vol. iii, p. 98, No. 2, 1840. Amyot and Serville, Hémipt., p. 412, No. 2, 1843. Herrich-Schiiffer, Die wanzenartigen Insecten, vol. viii. p. 110, Tab. eclxxxvi. fig, 880 9, 881 3g, 1848. Ovate, widest a little before ( ) or about (?) the middle. Ashy grey. Head with the usual ill-defined reddish marks at the hind margin. Antenne, legs, rostrum at base, and genital segments, fuscous black, clothed more or less with grey pubescence. Hind margins of the ventral abdominal segments sometimes obscurely luteous. Antenne: third joint 48 THE VOYAGE OF H.M.S. CHALLENGER. shorter than the second ; fourth subequal in length to the second and third taken together. Front tarsus with first joint less than one-half (two-fifths) the length of the second. Middle tarsus with first joint seven times longer than the second. ¢. Length 3, breadth 1°75, middle femur 3°25, hind femur 2°5 mm. @. Length 3, breadth 2, middle femur 3, hind femur 2°25 mm. Habitat.—Next to Halobates wiillerstorfi, the most abundant species, but almost con- fined to the North Pacific Ocean, over which, within or near the tropics, it is widely diffused. Less abundant in the South Pacific. Two specimens, which seem inseparable from sericeus, were taken by the Challenger in the North Atlantic, near the Cape de Verde Islands. Amyot and Serville record its occurrence near the Cape of Good Hope, and Fairmaire from near Madagascar; but I have not seen specimens from either locality, and it is possible that these were not correctly determined, smce any small grey Halobates was always referred to sericeus. The specimens I have examined are from the following sources :— Challenger Specimens. North Pacific localities :—Many stations on the voyage from the Admiralty Islands to Japan, and from Japan to Honolulu (or—in other words—common between the equator and lat. 38° N., and between long. 137° E. and 154° W., thus ranging considerably north of the tropics). South Pacific :—Lat. 23° 46’ S., and long. 149° 59’ W. North Atlantic :—About lat. 11° N., long. 32° W. Specimens from other Sources. Pacific between Cape Horn and San Francisco (Liverpool Museum). ‘ Ocean Austral” (Berlin Museum). ‘“ Pacific.—Lat. 24°-34", long. 120°-115°” (Stockholm Museum). g. Ovate, widest a little before the middle. Ashy grey. Antennze, rostrum, legs, and genital seements fuscous black, clothed more or less with grey pubescence. Head with an ill-defined reddish oblong transverse blotch on each side at the hind margin. Eyes brown or, more rarely, yellowish. Rostrum for apical half, front femora, and last genital seoment below more or less shining black. Abdomen with the ventral hind margins some- times very obscurely reddish luteous. Antenne (Pl. I. fig. 7, a.) comparatively stout, about half as long as the body; first joint more than one-third shorter than the other three joints taken together; second incrassate upwards, about two-fifths the length of first; third cylindrical, shorter than the second; fourth stout, slightly and gradually incrassate upwards, subequal in length to the second and third taken together. REPORT ON THE PELAGIC HEMIPTERA. 49 Pronotum of the usual form, disk somewhat flat, rather hollowed in the middle posteriorly, and with a transverse fovea on each side anteriorly. Mesonotwm widest a little behind the front margin, disk very convex. Mesosterniin with a very indistinct percurrent longitudinal mesial line. Front legs: femora very stout (comparatively), nearly equally thick to middle, then narrowing to apex ; tibia about four-fifths the length of the femur; tarsus (Pl. . fig. 7, ft.) about three-fifths the length of the tibia, first joint two-fifths the length of the second, which is cleft about the middle. Middle legs: trochanters armed on inner side with short spines, as is the femur ; femur rather shorter than the tibia and tarsus taken together; tibia a little shorter than the tarsus ; tarsus (PI. I. fig. 7, m.t.) first joint seven times as long as second joint. Hind legs: femur armed as middle femur, about one-fifth longer than the tibia and tarsus together; tibia armed on all sides with scattered small spines; tarsus cleft at about two-thirds of the length. Abdomen: peculiarities of the connexivum have been noticed in the generic description. Genital segments: first below as long as four of the abdominal ventral segments, transversely convex, sides parallel. Second with the horns reaching about three-fourths the length of the third below; the margins of the horn (Pl. HI. fig. 24) are not thickened, and on the basal half are a few long hairs pointing inwards, and arising from the disk; apical half of the disk set with short, stout, outward-pointing teeth; near the base of the horn, and between it and the posterior angle of the segment, is a tubercle. Third segment above (Pl. L. fig. 7, g.), with the lateral angles moderately produced ; on each side below is a patch of sharp spines pointing forwards. ?. Ovate, widest at about the middle. Hind margins of the ventral abdominal seg- ments sometimes luteous. Head and mesothorax more convex than in the male. Front tibia nearly as long as femur. Middle legs: trochanters unarmed, femora less strongly armed. Sometimes the middle and hind legs are scarcely armed. Abdomen below (Pl. I. fig. 7, 2 ab. b.): segments Ist to 5th, each rather elevated in transverse middle line ; sixth with a suboblique transverse furrow not quite reaching the middle. Genital segments: first below as long as three of the ventral abdominal segments together, transversely convex, sides tumid, hind margin straight in the middle, each side somewhat oblique. Halobates sericeus has been found in March, April, June, July, and October, but pro- (Z0oOL, CHALL, EXP, —PART XIX.-—1883.) T7 iy) THE VOYAGE OF H.M.S. CHALLENGER, bably occurs all the year round. The larva resembles the adult, with the exception of the differences to be noted in the description of the metamorphoses. 7. Halebates germanus, n. sp. (PL I. fig. 6). Long oval (2 ) or shortly ovate (2 ), widest behind the middle. Dark ashy grey paler on the sides (2), or silvery ashy grey (?). Head with an obscure transverse rufous yellow mark on each side at the hind margin. Antennz and legs fuscous black above, dark fuscous brown below, clothed sparsely with grey pubescence. Base of antennee nar- rowly rufous ochreous. Front legs with coxe, trochanters more especially on inner side, and base of femora below ; middle legs with a spot on the acetabula below (broader and more distinct in the female) trochanters, and base of femora below ; hind legs with trochanters and base of femora, more or less indistinctly fuscous ochreous brown. Abdomen with hind margins of ventral segments fuscous ochreous. Genital segments : first below on disk and posteriorly, second above, and apex of third above, fuscous brown ; second below, especially at apex of horns, and most of third below, fuscous rufous brown, Antennee : third joint shorter and fourth joint longer than the second. Front tarsus : first joint rather more than half the leneth of second. Middle tarsus: first joint about five times as long as second. $. Length 3°5, breadth 2, middle femur 4, hind femur (?) mm. ?. Length 3, breadth 2°25, middle femur 4, hind femur 3 mm, Habitat.—North Pacifie Ocean and Celebes Sea (Challenger) ; China Sea (Giglioli). $. Long oval, widest behind the middle. Dark ashy grey, paler on the sides. Antenne and legs fuscous black above, dark fuscous brown below, more or less sparsely clothed with grey pubescence, Rostrum with the apical three-fourths shining black. Eyes dark brown.