a ee 0, Se Pre = SS Bee ee ON, Be oe Sap Rae) Reuse > . oe Eats ae SINE nb Seren 7 a , . 2 y pe i ue bane Rae LaCTIONS a Pl ¢ ; riaenre : i - a 7 tee s Oe OO ee oT : oy Coa @: Vins 7 rigeles 4 mint ay i, Pe ed) ) oy d h ¥ , ein Go) ed hee - ta hin ae eee | ae Se eae fo) epuatilae Yee tvid” Set 9) tas meni | 7 7. 7 ; ; Te | my es aiden : ivi - a ey 7») : i abe mile Savin Fae ‘ , ar Sane ae my ihe 7 . © AL A 7 r an ‘ a) - + ry , i 2 ‘ » - ’ i \ ae 7 7 i Py, a Cae hs _ P] 4) ae a hor Dye Ts Cin i. SMITHSONTAN MISCELLANEOUS COLLECTIONS lp & A. H e . +) Pr. ° “lp WLTHSOM SS. hg rl ty TIOepe Lee INGTON “EVERY MAN IS A VALUABLE MEMBER OF SOCIETY WHO, BY HIS OBSERVATIONS, RESEARCHES, AND EXPERIMENTS, PROCURES KNOWLEDGE FOR MEN’’—SMITHSON (PUBLICATION 3132) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION 1931 y tae i dlissanae : ae if i ° hy 4 Yay, ¥ j Al 4 1 e yee? é , \ —— . : ij é The Lord Galtimore Prees BALTIMORE, MD., U. S. A. ADVERTISEMENT The present series, entitled “ Smithsonian Miscellaneous Collec- tions,’ is intended to embrace all the octavo publications of the Institution, except the Annual Report. Its scope is not limited, and the volumes thus far issued relate to nearly every branch of science. Among these various subjects zoology, bibliography, geology, mineralogy, anthropology, and astrophysics have predominated. The Institution also publishes a quarto series entitled “ Smith- sonian Contributions to Knowledge.” It consists of memoirs based on extended original investigations, which have resulted in important additions to knowledge. C. Gy ABBOT, Secretary of the Smithsonian Institution. (iii) 7 a ij 7 i \ yee fe 4 Lv t ivas T TO; Idee CONTENTS . Aspot, C. G., AND FREEMAN, H. B., Absorption lines of the infra-red solar spectrum. 17 pp., 5 pls., Aug. 31, 1929. (Publ. 3026. ) Snoperass, R. E., The thoracic mechanism of a grasshopper and its antecedents. III pp., 54 text figs., Dec. 31, 1929. (Publ. 3027.) Assot, C. G., The radiation of the planet earth to space. 12 pp., 2 pls., Noy. 16, 1929. (Publ. 3028.) MILier, GERRIT S., JR., The Characters of the Genus Geoca- promys Chapman. 3 pp., I pl., Dec. 9, 1929. (Publ. 3029.) Miiier, Gerrit, S. Jr., Mammals eaten by Indians, owls, and Spaniards in the coast region of the Dominican Republic. TG pps, 2 pls Deci mis 1920.) (Pabk 3030;)) Berry, EpwaArp W., The past climate of the North Polar region. 29 pp., 6 figs., Apr. 9, 1930. (Publ. 3061.) Ciayton, H. Heim, The atmosphere and the sun. 49 pp., 33 text figs., June 9, 1930. (Publ. 3062.) Netson, E. W., Four new raccoons from the keys of Southern Florida. 12 pp.,.5 pls., July 10; 1920. (Publ. 3066.) HeEron-ALLEN, Epwarp, F. R. S., The further and final re- searches of Joseph Jackson Lister upon the reproductive proc- esses of Polystomella crispa (Linné). 11 pp., 7 pls., Nov. 26, 1030; .(Fubl;-3067. ) ScHEDL, Kart E., Morphology of fhe bark-beetles of the genus Gnathotrichus Bishi 88 pp., 40 figs., Jan. 24, 1931. (Publ. 3068. ) Haury, Emit W., anpD Harcrave, Lynpon L., Recently dated Pueblo ruins in Arizona. 120 pp., 27 pls., 35 text figs., Aug. 18, 1931. (Publ. 3069.) BusHNELL, Davin I., Jr., The five Monacan towns in Virginia, 1607. 38 pp., 14 pls., Nov. 18, 1930. (Publ. 3070.) Miter, Gerrit S., Jr., A note on the skeletons of two Alaskan porpoises. 2 pp., I pl., Dec. 23, 1930. (Publ. 3107.) Miter, Gerrit S., Jr., The supposed occurrence of an Asiatic goat-antelope in the Pleistocene of Colorado. 2 pp., 2 pls., Dec. 22, 1930. (Publ. 3108.) (v) vi 17a 18. CONTENTS Mitter, Gerrit S., Jr., Three small collections of mammals from Hispaniola. 10 pp., 2 pls., Dec. 24, 1930. (Publ. 3109.) Reese, A. M., The ductless glands of Alligator mississip piensis. 14° pp. 3) pls. March 9, 193t.. (Publis srr.) Kennarp, A. S., A. L. S., SALIsBury, A. E., anD WoopWARD, B. B., F. L. S., The types of Lamarck’s genera of shells as selected by J. G. Children in 1823. 40 pp., July 11, 1931. (Publ. 31125) McInpoo, N. E., Tropisms and sense organs of Coleoptera. 10 pp., 2 pls:, 19 text figs, Apr. 18, 1931. (Publ. 3113") iS ey a ae ’ r : , ' i ; ‘ % ; y + 7. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 1 ABSORPTION LINES OF THE INFRA-RED SOLAR SPECTRUM (WITH FIVE PLaTEs) BY CG. G. ABBOT AND H. B. FREEMAN (PUBLICATION 3026) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION AUGUST 31. 1929 The Lord Gattimore Press BALTIMORE, MD., U. S. 4+ ABSORPTION LINES OF THE INFRA-RED SOLAR SPECTRUM By C. G. ABBOT ann H. B. FREEMAN (WitH 5 PLATES) In the decade 1890 to 1900, the bolometer was used under Langley’s direction at the Astrophysical Observatory of the Smithsonian Institu- tion to feel out the positions of lines and bands in the infra-red solar spectrum. The results were published in Volume I of the Annals of the Observatory. In the spectral region A to 2, about 550 lines were recorded as observed in the spectrum of a 60° prism of ordinary telescope flint. At Mount Wilson, in the summer of 1928, Dr. H. D. Babcock urged that further bolographic studies of the infra-red solar spectrum should be undertaken with apparatus of higher resolving power. Our Bie. 2. vacuum bolometer equipment, then on Mount Wilson, presents a sensi- tive strip of approximately 0.1 mm. width, and the combined outfit of bolometer and galvanometer was certairily not less than five times as sensitive as the most sensitive outfit employed at Washington 30 years before. It appeared practicable to undertake a brief bolographic study of the upper infra-red solar spectrum from A to © in the time available. Accordingly we set up a spectroscope (fig. I) comprising a slit 6 cm. high and (usually) 0.4 mm. wide; a collimating cylindric mirror of 543 cm. focal length; a set of three telescope flint-glass prisms, two of 60°, the third of 64° angle, and all presenting faces approximately 6 cm. square. From thence a plane silver-on-glass mirror reflected the spectrum to an image-forming spherical mirror of 230 cm. focal length. The vacuum bolometer, above mentioned, whose sensitive strip was 16x 0.1 mm. received the rays at focus. The spectroscope SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 1 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS , VOL. 82 was fed by a two-mirror coelostat with silver-on-glass mirrors. The solar rays were not concentrated on the slit. Hence they represented the integrated rays of the entire solar disk. The infra-red solar energy spectrum was recorded on moving photo- graphic plates 8 x 24 in. in surface. The clockwork was arranged so that 4 cm. of plate corresponds to 5’ of spectrum, and the plate passed the recording light-spot of the galvanometer at the rate of 2 cm, in I minute. The three prisms were set according to computations so that the beam of rays of wave-length 1.054 would pass through each one of the prisms approximately in minimum deviation. This same setting was continued unchanged in all the observations. The total deviation of the rays of this wave-length was roughly 180° and the dispersion from A to 2 was about 5° 25’. Hence we were obliged to use five 61-cm. plates to cover the entire region with overlap sufficient for identification. Generally three curves of each of the five regions were impressed on a single photographic plate. Care was taken to arrange them vertically in close superposition, so as to facilitate comparison. Plates I to 5 give reproductions of some of the most satisfactory observations. Linear scales are drawn on plates I to 5 parallel to the direction of motion of the recording photographic plate. They have numbers closely agreeing with those of the extensive table 3 of linear measures and wave-lengths, given below. In each group of three curves the air-mass of observation decreases as between the several curves from the bottom upward and in each curve (except in pl. 5) from left towards right. In most plates there is a very considerable increase of air-mass between the upper and lower curves. This will facilitate the discrimination, by those interested, of solar and telluric lines. De- tails of times of observation and air-mass and notes on the conditions are given in table 2. A very considerable increase of detail appeared in these energy curves when compared with those taken 30 years ago with a single glass prism. In the A line, for instance, not only could the doubles be recognized, but in many of them the individual components were resolved separately in the energy curve. Some of the bands near wave- length 0.82 showed as many as five veridical lines in the new curves where only one broad band could be distinguished in the older work. The identification of lines was done entirely by Mr. Freeman, and in the following manner. A series of several bolographs was super- posed, either on millimeter cross-section paper or on a comparator NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN 3 in which a stretched wire was displaceable over a milk-glass back- ground. Lines were considered provisionally veridical when found as deflections of similar form and-similar setting in three or more bolographs. After completing this preliminary study, the positions of all deflections considered possibly veridical were measured on three bolographs with the excellent Warner and Swasey comparator de- scribed on page 64 of Volume I of the Annals. Mean values were computed of positions on three (or in some cases two) of these bolographs on which the deflections were found. When found on only two of the three they were questioned, and rejected unless supported by further evidence. In assigning intensities, Mr. Freeman used practically the same system that was used in Volume I of the Annals. Grades a, b, c, d, and d? were employed. All lines falling within great bands like A, por, ¢, w, and © are joined in a bracket and designated as a whole with “a.” Bands hardly reaching this first-class prominence are similarly bracketed and marked “ b.” Individual deflections, or com- posites of several small deflections which altogether make a depres- sion of 5 mm. or more in bolographs are marked “cc.” Smaller indi- vidual deflections, whether in the bands or outside of them, are marked “d.” When considerable doubt remains as to the veridical character of such a deflection, it is marked “d?.” We do not guarantee that all the lines included in the table are veridical, but we believe a very large proportion of them are so. The curves are very free from accidental deflections as deep as a single half millimeter, and the repetition on several bolographs of similar configurations of intensity “d” is regarded as strong presumptive evidence of reality of corre- sponding solar or terrestrial absorption lines. To determine the wave-lengths of the lines observed, the advice of Dr. Babcock was sought. From his studies of all existing laboratory determinations of infra-red line spectra, amplified by his own extensive photographic work in the upper infra-red spectrum as far as A= 1.1018 Angstroms, he sent a list of 112 identifications of wave-length places, given according to our bolographic work in Volume I of the Annals, as compared to more recent determinations. A curve of cor- rection to the wave-lengths given in Volume I of the Annals has been prepared from this material. In summary it is as indicated in table 1. The data for corrections beyond 1.18 are so scanty and so conflict- ing that there seemed no justification for applying any corrections in that region. 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 TABLE 1.—Corrections to Wave-Lengths of Annals, Volume I (Corrections are stated in Angstroms, wave-lengths in microns.) Wave-lengths...| 0.76 to 0.84 | 0.85 | 0.86 | 0.87 | 0.88 | 0.89 | 0.90 | 0.91 @orrections.-..- O +5 +5 +5 +3 +2 fe) —2 Wave-lengths...| 0.92 | 0.93 | 0.94 | 0.95 | 0.96 | 0.97 | 0.08 | 0.99 | 1.00 Gornections.-5- —2 | —I fe) +2 +2 +1 0 \os=3 1 es Wave-lengths...| 1.01 | 1.02to 1.06 | 1.07 | 1.08] 1-09] 1.10| 1.11/1.12|1.13 Corrections... ..- —8 —I10 — 9 | —7 | —6|] —5 | —4 | —3 | —1 I.14 to end 0 Wave-lengths... Corrections..... In further determination of wave-lengths, Mr. Freeman identified 81 deflections as corresponding each to each in the old and the new bolometric work. These deflections covered fairly uniformly the range from 0.76u to 1.804. Having taken out from the tables of Volume I of the Annals the corresponding wave-lengths, he then applied to these values the corrections fixed by table 1. He then plotted on a sufficiently large scale the observed linear places of these 81 deflections as ordi- nates, and the corrected wave-lengths as abscissae. The curves thus defined could easily be read off to a single Angstrom. From them were read all the wave-lengths given in table 3, which contains over 1200 lines. TABLE 2—Circumstances of Observation Time Air-mass Date a 1928 Curve Start Finish Start Finish Notes Sentara aca I 0: 39 10: 09 Legit 23 2 MOE: 107 10: 47 ee 1.16 10: 52 II: 22 Te is Wo l2 Sentifaaeoe ce I 6: 28 6:58 4.85 3823 2 FE RIO) 8: 29 1.07 1.69 3 8:51 Q: 21 1.54 1.38 Septins. eee. I 6: 34 7:04 4.49 3.05 Sheht earthquake 2 Gj? fil 9: 41 1.43 pitt 3 9:50 10: 20 1.28 1.20 Sepitere ays arerat I 6: 29 6:59 4.70 Bio 1s 2 9:19 9: 49 1.36 Te27) 3 9:58 10: 28 1.24 Tay, Septreiiacenscee 3 3:34 3:54 1.82 2.18 Ends off plate 2 2:58 a8 BS 1.54 70 I Tens TA 1 17 123 NO lat INFRA-RED SOLAR SPECTRUM—ARBBOT AND FREEMAN TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum Linear measures —34.130 34.035 33-103 32.858 Intensity VW aAanmaanananaanaanaAaAAnaAAAAAnaAnaAannananAamA Wave- length 7582 7583 7508 7602 7604 7600 7608 7618 7628 7630 7636 7638 7641 7642 7645 7640 7647 7051 7652 7656 7658 7661 7662 7665 7668 7672 7674 7675 7680 7684 7686 7601 7692 7695 7608 7701 7793 7795 7797 7710 Fifi 7712 7714 7718 7722 7725 Linear measures — 25.233 22 25.019 24.831 .418 322 -233 153 24.030 23.801 .696 573 461 .176 23.079 22.904 .690 621 .272 ily 22.046 21.906 807 .696 472 343 .240 21.005 20.871 .687 521 318 20.114 19.935 826 .756 .650 547 .226 10.111 18.951 837 755 18.080 17.949 830 Intensity ~w =! BaAAaAAAAAAKAAAA A CEO CW) wv QaaannnnaaaanaAAAAAAannAAaAanAananaaamha “w : Wave- length 7727 7728 N SSS Se ee DS SS ESS SS SS ee fl i ast 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 TasLe 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length 17720 d 7852 —5.692 d? 8069 16.273 d? 7878 5.570 d 8071 15.621 d 7889 4.806 d 8084 cago id 7804 “Capea idl: 8086 15.136 d 7808 635 d 8088 14.932 d 7901 500 d? 8001 .823 d 7903 .400 d 8003 .644 d 7906 .286 d 8095 470d 7909 Ar53 (od 8007 14.207 d 7914 3.747 d 8106 13.910 d 7919 645 d 8108 625 d 7924 543 d 8109 .500 d? 7926 384 d 8112 .406 d? 7928 .206 d 8114 .196 d 7932 3.105 d? 8118 13.050 d 7934 2.967 d 8120 12.861 d 7937 658 d 8126 704.) od 7939 537 (7d 8129 .676 d 7941 378 d 8132 450 d 7945 2.255 d 8134 1275 d 7948 1.839 d 8142 12.055 d 7952 536 d 8148 11.844 d 7950 .338 lc 8152 .720 d? 7958 238 d 8154 .604 d -c 7900 .142 d b 8156 324 d 7966 1.062 d 8157 208 d 7968 0.812 d 8162 11.004 d 7072 739 d? 8164 10.619 d 7979 0.000 € 8178 9.866 d 7992 .123 d 8181 765 d 7904 | .469 d 8188 688 awd 7906 Or bad 8100 389 d 8001 | 0.775 d 8103 283 d 8003 +1.037 d 819090 0.102 d 8006 | 349 d | 8206 8.098 d 8008 | EL ol ae a! 8214 8.249 d 8022 1.854 d 8216 7.982. d? 8027 2220) ) a? 8224 818 d 8020 .206 d 8225 530 d 8035 392 d 8228 hist d 8038 468 d? b 8220 7.011 d 8044 -700 d 8233 6.927 Gly fete 8045 2.800 d 8235 769 d 8048 3.028 d 8240 647 d 8051 .243 d 8244 6.541 d 8053 336 d 8246 5.055 d 8063 463 d 8249 856 d 8065 5690 d 8251 NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length +3.612 d 8252 +12.086 d 8430 691 d 8253 12.518 d 8440 .820 d | Es 8256 13.006 d 8450 3.927 d 8258 128 d? 8453 4.036 d 8260 .243 d 8455 -706 d 8274 .675 d 8465 794 +~d 8275 13.9048 d 8470 4.892 d 8277 14.416 d 8480 5.108 d 8282 14.509 d 8484 Tor. od 8283 15.042 d | 8404 .421 d 8288 .132 d 8406 .482 d 8280 .231 d ve 8408 506 d? 8201 333 d | 8500 5.829 d 8207 .604 d 8508 6.124 d 8303 15.037 d 8513 .233 al He 8305 16.046 d 8516 304 .- d? 8307 1g2) a ] 8517 .476 d 8310 360 d 8523 S05) . ‘d 8311 16.468 d ¢b 8525 .668 d 8314 17.033 d 8537 6.996 d 8321 218 d 8541 7.163 d 8325 17.947 d 8558 431 d 8330 18.144 d 8562 549 d 8333 260." di? 8565 .666 d | 8335 .456 d 8560 qos. dd 8337 2550", dd 8572 8.003 d 8342 761 d 8576 200), id 8346 18.864 d 8570 .490 d 8352 19.044 d? 8583 743 «2d 8358 138: d 8585 8.888 d 8361 .242 d 8587 9.204 d 8368 19.722 d 8500 317 d 8370 20.251 d 8611 394 d? 8372 398 d 8614 .467 d 8373 20.610 d 8620 575d 8376 21.060 d 8630 o731": d 8379 201 d 8633 10.023 d 8385 .488 d 8640 .260 d 8301 591 d 8642 499 ~d 8306 21.692 d 8645 .697 d 8400 22.256 d? tp 8658 10.814 d 8403 381 d 8662 11.043 d 8407 404 d 8663 .288 d 8413 22.625 d 8667 5900 d 8420 23.056 d? 8677 11.966 d 8428 254 d 8682 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 TasLe 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length +23.472 d 8687 +32.148 d 8805 562 d 8089 226 d 88907 684 d? 8692 348 d? 8900 23583 4d 8694 5201 «acl? 8904 24.568 d? 8713 733 d ) 8909 25.223 d 8728 32.901 d | 8915 302 «od 8732 33.101 d | 8918 tod 8735 419 d | 8926 506 d? 8737 33.860 d | 8937 1682), \ 4d 8739 34.014 d | 8941 25.823 d 8742 222 © «d? | 8946 26.181 d? 8750 414 d | 8051 288 d 8753 .740 d 8959 .460 d 8757 34.801 d b 8062 705 oad 8763 35.0900 c | 8067 302, - d 8766 448 d | 8076 26.931 d? 8768 35.791 d be 8984 27.052 d 8772 36.049 d 8990 43nd 8774 Bee 8 Gl 9004 261 d 8777 Ges d goo 404 od 8782 36.805 d Qo14 689 d 8787 37.060 +d 9018 27.996 d 8704 680 d 9036 28.105 d 8707 37.819 d 9039 223 «od | 8800 38.004 4d 9047 E332 d 8803 .180 d? 9049 385 d Ve 8804 502 d 9060 ce) | 8811 Beceem 9060 783 d 8813 38.074 d? 9071 .879 d 8816 39.582 d 9087 28.973 d 8818 .783 d bp 9092 20.247 d? 8824 878 d 9095 .402 d 8820 39.892 d 9096 524 d 8832 40.040 d? Q100 .720 d 8837 .192 d P gro4 823 d 8830 1273 d F 9106 29.903 d 8841 40.603 d OII5 30.036 d 8844 AT-GO2.) |) od | 9127 .166 d? 8847 .120 d ‘tc 9120 e3059 \) wal 8852 41.423 d | 9137 .540 d 8856 42.046 d Ik | O154 .667 d 88590 165 d tc Lh bq totex 843 d -c 8864 255 d | | Q160 30.041 d 8866 ‘800. id | 9175 31.128 d 8870 42.985 d 0179 247 d j 8873 43.047 d le oI181 31.881 d 8880 431 d | 9192 32.004 d? 8803 513 d? Q104 NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum —Continued Linear measures 41-43-7 11 43-884 44.101 .278 -347 525 .623 776 44.977 45.101 235 .310 .420 -540 .729 854 45-949 46.221 -337 836 46.907 47.101 3212 533 47-637 48.205 -205 509 48.817 49.124 49.648 50.022 51.122 .204 328 421 51.737 52.107 52.523 53-039 487 53.963 54.060 -174 54.278 55.008 Intensity GaOoamamanmaaAaA A —-—- —-———— YY ~w mw TAHAaAaAanaanannntAaAhAAhAhAaAaAanhAaAAnAnhAaatamananas lo) SS ao rb — Wave- length 9200 9204 9210 9215 9217 9222 9225 9229 234 9238 9241 9244 9247 9250 9255 9258 9261 9269 9272 9286 9288 9204 9296 9305 9308 9324 9327 0333 9342 9351 9366 9376 9409 Q412 9415 9418 9427 9439 0451 9467 9480 9495 9498 9502 9506 9529 Linear measures +55.674 50.010 369 50.738 57-254 57-503 58.073 -245 .352 534 58.667 59.058 472 568 59.642 60.482 773 60.975 61.069 544 61.931 62.229 .532 634 62.745 63.103 .666 63.956 ° 64.252 724 .898 64.085 65.224 342 .464 561 65,603 66.141 285 421 617 66.923 67.250 .486 675 67.772 9 Intensity d Q ae amend inn in BAAOAAAhAAAaAARhnAnhAnmhAAaAAAAAGA a) ed aQ BAAAAAAAARAARAAAARAAAA ~ Wave- length 9548 9558 9508 9580 9596 9604 9621 9626 9620 9634 9639 9651 9663 9666 9668 9694 9704 9710 9713 9727 9739 9749 9758 9761 9765 9777 9795 9804 9814 9829 0834 0837 0845 9848 9853 9856 9860 9874 9879 9883 9890 9900 goto 9917 0024 9027 10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 TaBLe 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length +68.099 d 9937 +74.504 d IOI50 .248 d 9042 .626 d 10154 643 d 9954 -750 d 10159 751 d 9958 74.912 d 10164 1870. | ‘d 9962 75.211 d 10175 68.9907 sd 9066 sat di? 10179 69.0908 d 9909 520 od 10186 235"), 1G 9973 708, id 10192 375...) a 9978 75.830 d 10104 Sy i) od 9083 76.001 d? 10202 615 d 9986 .108 d 10206 772 d QgoI 329 d 10214 863 d 9004 2510) id 10221 69.972 d? 9097 .631 d 10224 70.060 d 10000 76.765 d 10229 .179 d? 10004 77.033 d 10239 401 d? 10010 L227, d 10245 509 «od T0014 1933." od 10249 .634 d 10018 .470 d 10254 -706 d 10024 732 d 10263 70.044 d 10028 77.855 d 10268 71.061 d 10032 78.019 d 10274 452 d 10044 .150 d 10278 .562 d 10048 .289 d 10283 .676 d tb 10053 368 d? 10286 780 d 10056 Ay d 10292 878 d 10060 AGG Cal 10206 71.083 d 10063 757 d? 10300 72.088 d 10067 827 d? 10302 .220 d 10072 78.961 d 10308 natin) d 10075 79.088 d 10312 380 d? 10077 1217 d? 10316 -404 d? TOO8T 346 d 10321 .603 d 10084 534 d 10327 .719 d T0088 Wee d 10334 72.821 d? 10092 842 d 10338 73.023 d 10099 79.908 d? 10344 .139 d 10103 80.219 d? 10352 238 d 10106 .320 d? 10356 317 d? IO1I09 521 d 10363 401 d? 10112 6190 d 10367 514 d IOIIO. .721 d? 10370 691 d 10122 833 d? 10374 73.990 d 10132 80.988 d 10379 74.208 d 10140 81.105 d 10384 323 d 10144 .220 d 10388 NO: I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN Wu TaBLe 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear measures +81.324 .450 .569 81.680 82.016 .120 Intensity d d d? any, BA AAAAaAaaohAaAaaahnadahnannhnamaamaanhnanmaaaaaasa “vu Wave- length 10392 10396 10400 10405 10417 10421 10428 10432 10437 10441 10450 10453 10457 10462 10467 10479 10484 10490 10494 10408 10510 10518 10525 10537 10547 10556 10561 10578 10585 10504 TOOOI 10607 IO6II 10621 10623 10636 10643 10650 10662 10673 10680 10684 10688 10604 10607 10708 Linear measures +89.892 89.995 90.139 336 441 533 90.753 OI.091 249 344 .467 .566 .667 776 91.953 92.260 472 550 654 782 .866 92.980 93.046 232 -393 .487 Gian 93.962 94.050 .469 554 .679 94.777 95.373 506 625 95.860 96.124 -234 353 96.782 97.003 -119 272 383 .485 Intensity d? BaOaOMOaOAMAAaAAAhAaAaAaaAhnoahmAhanaAahnnaaanmanhnanaanaananhamamanhanhanmana vu Wave- length “10714 10719 10724 10732 10736 10740 10749 10762 10768 10772 10777 10781 10785 10789 10796 10808 10816 10820 10823 10828 10832 10836 10839 10845 10852 10855 10866 10874 10878 10894 10808 10902 10906 10930 10936 10941 10950 10960 109064 10969 10986 10996 11000 T1006 IIOII IIOIS [2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear measures +97.673 97.898 08.211 -203 .400 -509 98.737 99.101 -435 .707 99.806 100.387 473 100.900 IO1.102 101.704 102.378 -447 .862 102.960 103.224 761 832 103.934 105.170 105.993 106.242 -595 684 106.790 107.588 107.855 108.607 723 108.808 109.102 380 109.702 110.141 P2R7, E72 110.912 ITI.116 .587 ITI.669 Intensity aaamamaa fv) ~w AaanannannanaaAntananAAnATFAnAnaanAnananhananamm&Aa inn Wave- length 11023 TIOS2 2 11045 11048 11052 T1057 11066 11081 11004 11106 EEE T1133 11137 T1155 11165 IIT190 J1217 11220 11238 11242 11254 11278 11281 11285 11340 11376 11388 11404 11407 T1412 11448 11460 11401 11406 11409 TISII 11524 11537 T1555 T1559 11574 T1588 T1596 11616 11620 Linear measures + 112.005 .187 292 112.888 113.051 152 .466 614 113.948 114.119 823 114.916 115.428 115.821 116.084 397 116.914 117.034 .140 117.726 118.034 -154 322 448 .600 720 118.828 119.133 2211 -334 440 119.738 120.059 .232 120.424 T2027; .200 303 427 821 121.9014 122.022 -134 248 .406 Intensity BOAAAMAAARARARAAhAAnAAaaAAanAaananaaaana BaqnrRAAhAAnnAnanhnmaAa Aa Wave- length 11634 11642 11646 11670 11678 11682 11696 11702 11716 11723 11754 11758 11780 11797 11808 11822 11845 T1850 11855 T1881 11895 11900 11908 IIQI4 11921 11927 11931 11945 11949 11954 T1959 11972 11988 11996 12000 12038 12042 12046 12052 12071 12075 12080 12085 12001 12008 NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN 13 TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear measures +122.514 {oni 122.759 123.132 gi .480 -594 .720 842 123.957 124.044 -177 .438 124.918 125.023 -197 Sirs 396 -495 .627 -707 125.859 126.113 .204 AII 579 .700 -799 126.941 127.047 173, 303 .406 536 644 734 839 127.914 128.025 Heit .222 -309 415 546 667 783 Intensity a & vu wow “vu WU} B@AaaAaAAMARAHRAAAKAAAARAAAAMAAAk Aa vu foal ary ba aaaam Qe Oe aaadaamdmama Wave- length 12104 12108 12115 12133 12140 12150 12156 12162 12168 12173 I2177 12183 121096 12219 12224 12232 12236 12242 12247 12254 12257 12205 12277 12286 12204 12300 12306 12310 12317 12322 12329 12335 12340 12347 12352 12356 12362 12366 12372 12376 12381 12386 12301 12308 12404 12409 | Linear measures +128.914 129.009 .219 319 -437 504 129.903 130.009 Ain) 248 338 545 130.767 131.216 .409 .526 .620 Gin 838 131.927 132.006 -193 agit 307 -473 .600 608 132.799 133.551 134.119 304 134.469 135.049 .201 weil 401 .507 .620 135.961 130.071 186 619 807 136.937 137.031 150 Intensity a paar QaoamnaAanAhnanhtaannaanaahaanhAahaaaaa & & ao d Wave- length 12410 12422 12432 12437 12443 12450 12468 12473 12478 12485 12489 12501 12512 12536 12540 12552 12550 12562 12568 12572 12577 12586 12593 12506 12601 12608 12613 12618 12658 12688 12608 12707 12730 12748 12753 12759 12764 12770 12788 12794 12799 12822 12833 12839 12845 T2851 [4 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length +-137.264 d 12858 + 143.603 d | 13198 .4II d 12866 W277, d | 13205 493 1 od 12870 834’ id) 13210 578 d? 12874 143.940 a hg 13217 137.878 d 12891 144.013 d 13221 138.016 d 12898 114 .d 13226 Teen d 12903 .867 d 13267 .231 d 12909 144.959 aq \h 13272 .301 d? 129013 145.434 d 13209 .427 d 12920 508 d 13302 806 d 12940 732 d? 13314 138.930 d 12945 145.820 d 13319 139.048 d 12053 146.484 d 13355 212 d 129062 146.565 d 13360 324 d 12968 147.020 Cc 13385 .489 d 12976 199 c 13306 500 id 12983 147.738 ¢ 13425 7735 d 12990 148.417 Cc | 13464 835 d 129095 .905 d? 13401 139.942 d 13001 148.901 d 13495 140.038 d ] 13006 149.005 d 13501 114 d [ 13010 350 d 13516 210 d rc 13015 .446 d 13522 303: nd 1302¢ 549) iy di rc 13527 424 d 13026 651 d 13532 2025) 13037 149.744 1d 13538 719 d 13042 150.069 d 13555 834 d 13048 .144 d 13560 .926 d 13053 461 d 13578 140.907 d? 13057 508 d le 13580 141.086 d 13061 793 d | 13507 308 d } 13074 150.910 d 13604 .412 d i 13080 151.259 i: | 13623 520 d | 13085 358 doc 13628 617 d 13090 442 d | 13634 141.877 d 13104 815 d | 13654 142.120 d 13118 151.920 d 13660 .236 d 13124 152.024 d? tc 13667 bBRO indus 13120 28a id? 13681 449 42~d 13136 “303° ad 13687 564 d 13142 S45 gids »| 13606 Os th wud 13150 Ts2ee5 ) id i 13716 844 d 13158 153.024 d rc 13724 142.062 d 13163 163 d La772 143.070 d 13170 273 d? 13738 216 aivilre 13178 .467 d 13740 330) aiud 13183 866 d 13772 .446 d 13190 153.956 d 13777 NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN 15 TaBLe 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear measures +154.208 .206 617 724 154.808 155.010 113 [222 .408 .507 155-936 156.826 157.693 158.425 759 158.859 159.280 587 159.691 160.140 .632 160.969 161.049 -379 534 161.675 162.033 104 162.476 163.155 163.520 164.005 433 .515 755 164.973 165.479 166.341 167.125 167.435 168.031 119 .495 168.033 169.060 765 Intensity d? | | 2 aS mm SS) Q “wu a TAA nDTAAnHTFAAAAA AAA MA & Q loi TTrTAndqnAn AA rFTrTAAnangnartrtanA vu Wave- length 13781 13796 13815 13821 13833 13838 13843 13850 13860 13866 13890 13942 13094 14030 14057 14060 14086 14103 14100 14135 14164 14184 14188 14206 14216 14225 14245 14250 14271 14312 14333 14366 14385 14390 14404 14416 14447 14495 14542 14560 14594 14590 14621 14646 14655 14606 Linear measures + 169.987 170.701 170.883 171.330 618 171.990 172.090 .501 172.604 173.270 .360 173.918 174.011 win .436 174.805 175.205 £332 175.987 176.007 .580 842 176.967 177.301 .467 677 177.799 178.131 .200 .408 -597 715 775 883 178.980 179.115 201 Intensity ~~ a Q Coy vu J) (or ow uy ow, GS Be as ein Ps) Bk (PsP Pas Oe Ake Ces Bae RS ee BSR Rm BARA AAAAAnRnaAAAaAnAgqgnhnanA A. Aa A wm; Wave- length 14708 14756 14760 14788 14804 14826 14832 14855 14862 14901 14907 14938 14044 14962 14969 14991 15014 15021 15060 15070 15100 15112 15120 15144 15150 15162 151690 15180 15108 15211 15217 15224 15228 15234 15240 15248 15253 15200 15267 15276 15203 15310 15317 15324 15347 15356 16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 TABLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear measures + 181.173 615 -690 824 181.930 182.058 .206 481 182.959 183.182 -207 478 782 183.881 184.420 184.707 185.016 644 185.745 186.107 -353 -493 186.705 187.001 365 187.759 188.458 661 188.908 189.338 190.081 -479 190.754 191.205 313 551 .604 191.889 192.065 .207 563 192.713 193.051 .148 278 .501 Intensity wu O45) QaAaAAaAahhanaAaahanhaaaa ea fol (ary (eh (oh aoAmnaanaaqanhmaamama & = Wave- length 15371 15397 15402 15410 15416 15424 15436 15447 15478 15491 15499 15509 15527 15533 155006 15583 15601 15639 15044 15671 15680 150890 15702 15719 15740 15764 15806 15818 15833 15859 15904 15927 15044 15971 15977 15001 16000 16012 16022 16037 16052 16062 16082 16088 16005 16108 Linear measures +193.742 193.897 194.049 245 431 .507 682 854 194.981 195.111 308 -557 780 195.958 196.103 .207 196.607 197.052 234 .503 .640 .770 .900 197.994 108.157 212. -449 825 198.964 190.344 -544 .660 199.923 200.085 -235 305 cr 678 200.950 201.054 282 .695 201.778 202.134 244 202.775 Intensity wv Brus, ony ~v BaBOaAAaAaAanahnhaAahnhamaanahnamanmaha vu AaaaaaaaAa ei] uy nw) = “vu jay (ov fel [al fork [al (oly alk fob fal [aly [aly (oly jak -U Wave- length 16122 16132 16141 16154 16165 16170 16180 16190 16108 16206 16223 16232 16246 16256 16265 16272 16301 16322 16333 16350 16358 16362 16373 16379 16390 16309 16407 16430 16438 16462 16473 16481 16407 16507 16516 16524 16534 16543 16560 16566 16580 16605 16610 16632 T6651 16672 NO. I INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN Ly, TaBLE 3.—Lines and Bands in the Infra-Red Solar Spectrum.—Continued Linear Wave- Linear Wave- measures Intensity length measures Intensity length +203.065 d 166890 +214.210 d | 17380 225 d 166909 214.591 Cc 17404 203.421 d 16711 215.326 c 17449 204.042 d 16748 215.855 d? 17482 3365 d 16768 216.083 d 17495 417 d? 16772 .207 d +c 17504 .550 d? 16780 422 d? 17510 204.851 d 16798 754 d 17537 205.087 d 16812 835 d 17542 .443 d 16834 216.959 d 17550 SY, d 16839 217.123 d 17560 .678 d 16848 217.662 c 17593 789 d 16858 218.336 c 17634 205.982 d 16865 218.958 d 17673 206.140 d 16877 219.168 d 17686 206.630 d 16907 .288 d 17602 207.242 4d 16044 Bao sd 17704 320 d 16950 219.607 Cc 17718 .630 d 16969 220.119 d 17744 207.863 d | 16084 724 c 17782 208.031 d? | 16904 857 d? | 17790 245 d 17006 220.988 d b 17797 492 d 17022 221.105 d | 17805 208.960 d 17051 743 d 17843 200.367 d 17077 221.933 d \ 17855 .490 d 17084 222.043 din® 17862 200.758 de 17102 222.538 d | 17892 210.031 d 17119 223.207 deiac 17937 544 d 17150 223.520 d 17952 .846 d 17168 224.172 Cc 17902 210.965 d Q 17176 .692 d 18024 211.700 d 17223 224.904 Gaaac | 18042 211.822 d a 17220 225.155 d 18052 212.284 Cc | 17258 742 d 18088 880 cL 17200 225.017 d 18100 212.981 de fe 17304 226.318 d 18124 2133537 d 17338 .469 d 18132 .668 d 17347 226.816 d 18154 Gs. dis te 17353 227.152 d | 18174 213.910 d? 17362 227.486 d 18194 oe oe | ae > -_ - SMITHSONIAN MISCELLANEOUS COLLECTIONS { Botocrarns or THE INFRA-Rep PrisMATIC SOLAR SPECTRUM. The A region, Wave-lengths 7600 to 8600 Angstroms. VOPR 3 2.eNOreti) peae SMITHSONIAN MISCELLANEOUS COLLECTIONS VOES S27 NO dG been4: 2 180 | t., 7b my - et, . i SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82, NO. 1, PL. 5 Ay BoLoGRAPHS OF THE INFRA-RED PrisMATIC SOLAR SPECTRUM The region. Wave-lengths 15200 to 18200 Angstroms bas f a f Saeel : | P| 3 j e I F ; 1 , ‘ 6 f - / t i I =z a ' ; \ c 1 * vy i i i i ‘ { ' i ; iy ‘ oT \ : » - " (Hise ‘ { ‘ fd me i Wes he un | * , ’ la “a if) } Bie i ‘ é - > 1 ij ‘ j : A i I ah ' 4 oe, Mey. , Pasig ee WALT eae a ‘ ‘ > é i i « ' of [ 1 © Le ad , f : A ~ ro a = » t i 1 y ; ) "i "y : ' + ) Ua i 1 i ‘ i ) A i i ' ’ f DIS A aK eS J J fi rod ° i Wied ae ALSTON Sn) SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 2 THE THORACIC MECHANISM OF A GRASSHOPPER, AND ITS ANTECEDENTS BY R. E. SNODGRASS Bureau of Entomology, U. S. Department of Agriculture m SO 7 s\o) b (PUBLICATION 3027) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION DECEMBER 31, 1929 TBe Lord Baltimore Press BALTIMORE, MD., U. S. A. THE THORACIC “MECHANISM OF A> GRASSHOPPER, AND TYS*ANTECEDENTS By R. E. SNODGRASS BuREAU OF ENTOMOLOGY U. S. Department of Agriculture CONTENTS PAGE IPT CHEMIE STONER yas, a, «= Gok ETN gee eM tae Bee IRAN tLe had es pce ides I Peet Ali CISCUSSION :.. csee Lie toe enero aes era lets cos, ie elas beg aeons Sd 3 Wie yehoracie tergela ce elvatcre eee eee ear eio cre ee he ese tere Wh techies es 5 hex thoracie ’ pletirasceinae seco ee ee ee eee ie oe 10 Rhemthoracie stertiadaensa cee ee eT eo eee tater eee AA hieethesthoracic skeleton ot Oissosteuaeeneee isms eine ee eek 33 Whe scervical sclerttes. Steps eerie mes pce eas eee ierk acata cs abs oa 33 hes prothorax > bac aera Cee Cee Her eens, eros ie see es 34 Rhea pterothoraxy je scs se coe IIe Ac enna e es flere orion a 48 37 Diieehesthoractc: muscles) on Mrssosrcoraaeeseneae tee deere eine ae 51 Nimsclessor the neckandsnnothonaxeeemoeieer sini ss oeinesitie asic 53 Murscles: of the pterothiotas sr racrocterat teres crieienetons +t ere psieus creme ake uses 59 eieemesothoracic miutisc esmeennr errata re eerae eis ieee cer 60 ihe smetathoracicmusclessemernememm racemic cei alee: 66 Werine. lees and their niscles soaeesarne see sae ae sheet Aceh e'e als 72 Structire: (of thestlegis.., yp cterertre ths Sneeeteie whe Sis tea eaanese cetera pa aie lov ares 73 Miuscles’of thea least raerere ere aric teen he erecta ce eat chia 78 Veo the wanes and. their mechaitsmenr tame tee. cies 2 hk races, nevaneo vs 84 Structure. ot the ‘winesaa meee ce nose satiate seats toons weds 84 Sih writes mechanisnne tyecuer tre se eee rs ithe an. inetd syagedacadase wars 92 Wile Res spiracles... sad 5 «trclerae- tale meee arse T a ae edn ereuas eal arp slab alee a ares acne 99 Abbreviations .used on the fie tnesa-eeme eerie cereals ete ee ies P= 108 TEC TS eS stele a I eta Seis ig UU bolo om Combe ao Clorecad oem Sod en aaeaoe 109 INTRODUCTION The principal elements in the motor mechanisms of arthropods are the muscles and the body wall, though the blood often plays an im- portant secondary part as a hydraulic medium. All movements, how- ever, come primarily from muscle contractions. A contracted muscle, when it relaxes, must be actively extended before it can operate again, and therefore muscles generally occur in antagonistic sets. But the muscles of insects are not necessarily opposed by other muscles ; the counter force may be produced by the elasticity of the part of the body wall on which a muscle is attached. For this reason it is often SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL, 82. No. 2. 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 found in studying the anatomy of insects that a muscle has no an- tagonist. Moreover, while most insect muscles are muscles of motion, some are tensors inasmuch as they appear merely to maintain rigidity between parts that are subject to strain from other muscles. The ectodermal cell layer of the body wall, or epidermis (commonly known as the “ hypodermis”’), is covered externally by a cuticula of which the general constituent is probably chitin, but in which other substances are deposited to form hardened areas called sclerites. The nature of the sclerotizing substances in insects is not yet known, but it appears to be definitely established that the sclerotic areas of the cuticula are not places where the chitin is thicker or denser (Campbell, 1929). Sclerites are secondary formations in the body wall, and it would be both interesting and important to know the physiological processes that produce them, for we should then be better able to evaluate sclerites as morphological units. The major plates of the body-wall of an insect are very definite structures that are consistently reproduced by the deposit of sclerotiz- ing substances throughout the whole series of insect forms, and some of them appear to be homologous with corresponding plates in other arthropod groups. On the other hand, all parts of the insect skeleton called “sclerites”’ in descriptive entomology are not of equal value. Many of them are simply areas of larger plates which have become secondarily demarked by lines of inflection in the cuticula that have formed internal strengthening ridges. The so-called sclerites in such cases are in themselves of no significance. The important morpho- logical features are the endoskeletal structures ; these are the rafters, the joists, and the upright supports that give strength to the edifice and enable it to withstand the strain of the muscles pulling on its walls. It frequently happens, however, that a primary region of sclerotiza- tion becomes broken up by a discontinuity in the hardening substance of the cuticula, thus producing true secondary sclerites. The inter- vening “ membrane ” may take the form of a narrow line of flexibility (‘‘ suture ’’), or it may cover a large part of the original hard surface and reduce the primary sclerotization to two or more widely separated plates. Or again, an original sclerotic area may be contracted to a relatively small sclerite, or it may be obliterated. It then becomes a question, if the primary plate has been given a name, whether we are to apply this name to the area originally occupied by the plate, or restrict it to the sclerotic remnants or remnant. It is the usual prac- tice to apply the name only to the sclerite, whatever its extent, and, if the sclerite is obliterated, to say that the part in question is obsolete NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 3 or lost. This usage has convenience for descriptive purposes, but it is likely to confuse our morphological conceptions, since an anatomical part is the same thing regardless of the nature of its surface covering. I. GENERAL DISCUSSION If all that has been written about the thorax of insects were true, or could be made to fit with our present knowledge of insect struc- Pe’ “ates on ie Pe acs \ / oe ~ | i \ / ra oS | Z Sen Ist Fic. 1—Diagram of the theoretical structure of a primitive thoracic segment. The tergum (7) includes the segmental and preceding intersegmental sclero- tization of the dorsum; the ventral sclerotization consists of a primary seg- mental sternal plate (Stn) and intersegmental intersternites (Jst) ; the pleural area is occupied by a basal subsegment of the leg, the subcoxa (Scx), divided dorsally into a eupleuron (Eupl) and a eutrochantin (Eutn). acs, antecostal suture; c, d, dorsal and ventral subcoxo-coxal articulations ; Eupl, eupleuron; Eutn, eutrochantin; Jsg, primary intersegmental line; J/st, in- tersternite; Mb, secondary intersegmental membrane; Pc, precosta; Scx, sub- coxa; Sin, primary sternite; 7, tergum. ture, there would be little need of prefacing a special description of the thoracic skeleton and musculature of the grasshopper with a gen- eral discussion. Science, however, is not a collection of facts but a concept in which to hold the facts. As our collections of facts become larger, our concepts must be altered and enlarged from time to time. Moreover, we often think that we have nicely fitted a fact into a mental container, only to discover presently that it does not fit at all, or that an important part of the fact has been left out. There is noth- 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 ing to do then but to discard the container or to remodel it as best we can to make it serve its intended purpose. The writer, therefore, finds it necessary to enlarge some general conceptions previously expressed concerning the nature of the thoracic mechanisms and their apparent evolutions from simpler origins, in order to accommodate new obser- vations that must be admitted. _ The primary intersegmental infoldings of the integument of arthro- pods are the original lines of attachment of the longitudinal muscles, and in most cases the principle longitudinal muscles are still attached on them. When the cuticula becomes sclerotized, the intersegmental inflections are usually converted into apodemal ridges, and a primary segmental plate is laid down in the dorsum and generally in the venter of each segment. In some cases the intersegmental sclerotizations take the form of narrow intersegmental sclerites alternating with the seg- mental plates. This condition is found more frequently in the ventral than in the dorsal region, though it exists dorsally in some insect larvae. The typical sclerotization of the dorsum of any segment in an adult insect consists of a plate (fig. 1, 7) which covers most of the dorsal area of the segment, and which is continuous anteriorly with the inter- segmental sclerotization bearing the intersegmental fold or ridge (fig. 2 A, Ac). The definitive tergum, therefore, occupies a primary segmental region and the preceding intersegmental region; it bears anteriorly a submarginal, intersegmental ridge, or antecosta (fig. 2 A, Ac), marked externally by the antecostal suture (figs. 1, 2 A, acs), and it terminates anterior to this ridge and its suture in a narrow lip, or precosta (Pc). The ventral sclerotization of the segment may take the same form as the dorsal sclerotization, as in the abdomen of most insects, where the definitive terga and sterna duplicate each other in structure (fig. 3). The functional intersegmental rings of the body in such cases are the posterior, non-sclerotized areas of the primary segments, and the definitive segmentation is clearly a secondary one. The sternal sclerotization, however, may preserve a more primitive condition, as in some of the chilopods (figs. 8, 15) and in the thorax of certain insects, where the primary sternal and intersternal plates remain inde- pendent (figs. 1, 2 A, Stn, Ist). In the membranous areas of the lateral, or pleural, walls of the seg- ment are implanted the bases of the segmental appendages. In most arthropods the basis of the appendage (coxopodite) is preserved as an integral limb segment. In the body segments of the chilopods, the thoracic segments of insects, and the ambulatory segments of decapod NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 5 crustaceans, however, it appears that the limb basis has become sub- divided into a coxa and a subcoxa, and that the latter has been incor- porated into the wall of the body segment (fig. 1, Sc), where it either forms a “ pleuron”’ supporting the free part of the limb, or also the base of the wing, or it becomes degenerate and reduced to small sclerites having little significance or function. Mp Pe \ \ ‘ Stn / i ras Ph: , DMek B ZPh ZPh Fic. 2—Diagram showing the relation of the longitudinal muscles to the tergal and sternal sclerites of the body. A, three successive segments in which the terga include the primary inter- segmental regions bearing the intersegmental ridges (Ac, Ac), but in which the primary sternites (Stn) and intersternites (/sf) are distinct. B, the tergal region of the thorax in an insect in which the precostae (A, Pc) are enlarged to form postnotal plates (PN). Ac, antecosta; ac, antecostal suture; DMcl, dorsal longitudinal muscles; Ist, intersternites; JT, first abdominal tergum; L, positions of leg bases; Mb, secon- dary intersegmental membrane; Pc, precosta; 1Ph, 2Ph, 3Ph, the three thoracic phragmata; PN, postnotal plates; Stn, primary sternite; V Mcl, ventral longi- tudinal muscles. THE THORACIC TERGA The dorsal plates of the insect thorax never retain in all three seg- ments the simple structure of the definitive abdominal terga, and in the Pterygota the mesothoracic and metathoracic terga are modified in various ways correlated with the development of the wings. The prothoracic tergum (fig. 4, 71) always lacks an antecosta, and the principal longitudinal muscles (DMcl) that extend forward from 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 the anterior phragma of the mesotergum (zPh) run continuously through the prothorax and the neck (Cv) to be inserted on the post- occipital ridge of the head (PoR). This ridge, as the writer has else- where contended (1928), is evidently the intersegmental fold between the first and second maxillary segments. The neck, therefore, must be derived from the posterior part of the second maxillary, or labial, segment and from the anterior part of the prothorax, there being no satisfactory evidence of the existence of a separate neck segment. If so, the first postcephalic intersegmental line, or that between the labial and prothoracic segments (fig. 4, 1/sg), must be contained in the membranized cervical region, where the protergal costa is lost. By the suppression of the primary intersegmental line between the head and Fic. 3.—Diagram of the body segmentation of an insect, and the primitive relation of the longitudinal muscles to the definitive segmental plates of the body and to the head; showing the reversed overlapping of the sterna between the thoracic and abdominal regions. Cv, cervix; DMcl, dorsal longitudinal muscles; H, head; JS, first abdominal sternum; JT, first abdominal tergum; Ppt, periproct, or terminal segment; S1, S2, Ss, thoracic sterna; 71, Tz, Ts, thoracic terga; V Mcl, ventral longitudinal muscles; XJ, eleventh abdominal segment. the thorax, giving continuity to the muscle fibers of two segments, the head acquires a much greater freedom of motion than it could have if it were attached to the body by an ordinary intersegmental membranous ring. The loss of the protergal antecosta deprives the prothorax of the possibility of being a wing-moving segment, and there is nothing to suggest that the prothorax ever possessed movable organs of flight. The reduction of the primitive gnathal region of the body and its con- densation into the head capsule, accompanying the transfer of the gnathal appendages to the head, shifted the center of gravity pos- teriorly in the insect’s body, and the paranotal lobes of the second and third thoracic segments were developed into movable wings, leaving the prothorax as a free segment between the head and the pterothorax. The most conspicuous modifications of the thoracic terga occur in the mesothorax and the metathorax of winged insects, where clearly NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 7 they are correlated with the part.the terga of these segments play in the mechanism of flight. In the Apterygota the corresponding terga are simple plates showing none of the special characters of the wing- bearing plates of pterygote insects. The first important tergal modifications connected with the develop- ment of the paranotal lobes into movable organs of flight pertain to the ridges upon which the dorsal muscles of the mesothorax and metathorax have their attachments. These ridges, which are the ante- costa of the mesotergum, the antecosta of the metatergum, and the antecosta of the first abdominal tergum, bear each a pair of apodemal plates, varying in size, that project into the body cavity to give in- creased surfaces of attachment for the greatly enlarged dorsal muscles (fig. 2 B, DMcl) which have become depressors of the wings. The antecostal apodemes, primarily intersegmental, are the thoracic phrag- mata (1Ph, 2Ph, 3Ph). The lengthwise pull of the dorsal muscles on the phragmata de- mands sclerotic continuity in the dorsum, since the function of these muscles as depressors of the wings depends on their ability to produce a dorsal curvature in the terga on the relaxation of the antagonistic tergo-sternal muscles. To insure action by the dorsal muscles the intersegmental membranes between the mesotergum and metatergum and between the latter and the first abdominal tergum must be prac- tically eliminated, and their suppression has been accomplished either by a fusion of the succeeding terga, or by a forward extension of the precostal lips of the terga into the territory of the membranes. In the second case, the precostae become postnotal plates (fig. 2 B, PNo, PN;), often of large size, lying behind the true tergal plates of the mesothorax and metathorax (T., T;), where they appear to be parts of these segments, to which, in fact, they do belong since they lie anterior to the antecostal sutures (ac, ac) which are the primary intersegmental lines. In those insects in which the fore wings are the principal organs of flight, the second thoracic phragma becomes partially or wholly de- tached from the metatergum, and both the phragma and the postnotal plate establish a close association with the mesotergum, while the ex- tremities of the postnotum commonly unite for security with the pos- terior dorsal angles of the mesothoracic epimera. In those insects in which the hind wings have taken on the chief function of flight, the middle phragma always remains attached to the metatergum, and the precosta is not enlarged. The third phragma may preserve its connec- tion with the first abdominal tergum, as it does in the Orthoptera (fig. 25, PN;), but in most cases it becomes more or less separated 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 from the abdomen and, together with the precosta, becomes trans- ferred to the metathorax, where the precosta forms a distinct post- notal plate united laterally with the epimera. Thus it is usually found that the segment which assumes the leading role in the flight mechan- ism is provided with a phragma at both its anterior and its posterior ‘end. Since the tergal plates of the mesothorax and metathorax are the intermediary elements in the wing mechanism between the dorsal mus- Fees / / Vi SA, 5; 19S D2. 208 Fic. 4.—Diagram of the typical relation of the head and the prothorax in : pterygote insects. Cu, cervix; Icv, 2cv, first and second lateral cervicai sclerites; DMcl, dorsal longitudinal muscles; H, head; r/sg, 2Isg, first and second primary interseg- mental lines; rPh, first thoracic phragma; Poc, postocciput; PoR, postoccipital ridge; PT, posterior arm of tentorium; Si, S2, thoracic sterna; SA, sternal epopryees Ss, spinisternites; 71, T2, thoracic terga; V Mcl, ventral longitudinal muscles. cles of the segments and the bases of the wings themselves, it is clear that a proper execution of their function depends upon the ability of each to respond to the muscle tension at its ends with a dorsal curva- ture reaching its maximum at the transverse line between the wing bases. For this reason, as Weber (1924, 1925) has pointed out, the terga of the wing segments are provided with internal ridges so ar- ranged that the force of the muscles will not merely deflect the an- terior and posterior parts of the plates, but will be distributed gradu- ally toward the middle from each extremity, and thus produce an even dorsal flexion with its apex between the fulcra of the wings. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 9 The posterior gradient of an alar tergum usually has the form of a V-shaped ridge with the apex directed forward and the arms diverging toward the posterior lateral angles of the tergum (fig. 5 B, VR). The anterior gradient is less commonly developed than the posterior one, but, when present, it generally consists of two ridges, the parapsidal ridges (fig. 5 B, PaR), converging from the anterior margin of the tergum toward the middle, where they usually terminate without meet- ing. In some insects the anterior part of the tergum is strengthened by a transverse prescutal ridge (PR). In addition to these more gen- eral endoskeletal structures of the tergum, there may be present also Pe Psc Ph ps acs fe Fse. Ph PR Ac _Aw mm» XM E-ANE Em —PNP AxC ae ‘ / AxC Rd f& B Rd Fic. 5.—Structure of a wing-bearing tergum, not including a postnotum, diagrammatic. A, dorsal. B, ventral. Ac, antecosta; acs, antecostal suture; ANP, anterior notal wing process; AxC, axillary cord; Aw, prealar process of tergum; Em, lateral emargination of tergum; Pak, parapsidal ridge; pas, parapsidal suture; Pc, precosta; Ph, phragma; PNP, posterior notal wing process; PR, prescutal ridge; ps, prescutal suture; Psc, prescutum; Fd, posterior fold, or reduplication, of tergum; Scl, scutellum; Sct, scutum; VR, V-shaped ridge; vs, suture of the V-ridge, or scuto-scutellar suture; WV”, base of wing. a variety of accessory ridges, or even lines of flexibility in the tergal cuticula ; but all such features are highly variable in different groups of insects, and homologies can be traced between them only within limited groups. On the outer surface of the tergum the positions of the endoskeletal ridges are marked by the lines, or “sutures,” of their inflection (fig. 5 A, ps, pas, vs). The tergal areas defined in this manner by the more constant of the inner structures can be identified as homologous in different insects, and some of them have been given distinctive names used in descriptive works (fig. 5 A, Psc, Sct, Scl). It is quite impossible, however, to follow the lesser modifications consistently through the various orders of winged insects, and attempts to do so have only led to confusion. In any case, it must be recognized that IO SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 the external “ divisions” of the wing-bearing terga have no signifi- cance in themselves; they are merely incidental to the formation of the internal ridges by cuticular inflections, the ridges being the true functional structures adapting the tergum to its part in the flight mechanism. THE THORACIC PLEURA The lateral walls of arthropod segments, or the areas along the sides of the body between the terga and the sterna, when dorsal and ventral plates are present, may properly be designated the pleural regions. The pleural areas of the segments are primarily membranous, and Fic. 6—Diagram of the theoretical elementary musculature of the segmental appendages. a-b, primitive dorsoventral axis of the appendage; J, tergal promotor muscle; J, tergal remotor; K, sternal promotor; L, sternal remotor; 7, tergum; S, sternum. within them are implanted the bases of the limbs (fig. 6). In some arthropods, as in many of the Arachnida, each limb basis occupies almost the entire space between the tergum and the sternum, and may be articulated to one or the other of these plates, or to both of them. In most cases, however, a membranous area partially or entirely sur- rounds the limb base. In this area there are sometimes developed true pleural sclerites, as in the chilopod family Geophilidae, where there is a series of lateral plates of the body wall lying between the terga and the leg bases (fig. 8 A, pl), or in the larvae of some insects where similar plates occur on the sides of the abdomen. In many arthropods, however, there are plates in the definitive lateral walls of certain seg- ments that appear to have been derived from the bases of the appen- dages. While such sclerotizations are, therefore, not true pleural prod- ucts, they are generally termed pleurites, and those of each side of each segment constitute collectively the so-called pleuron of the segment. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS Il It is claimed by Becker (1923, 1924) that the pleurites, the coxae, and the trochanters in the Chilopoda are formed, during the develop- ment of the individual, from numerous schlerotizations in the lateral -Eppd es WS ox Fic. 7.—Maxillipeds and pleuron of a decapod crustacean, Macrobrachium jamarcensts. A, first maxilliped, left, posterior surface. B, second maxilliped, right, an- terior. C, third maxilliped, left, posterior. D, left pleuron, or inner wall of bran- chial chamber. Brn, branchia, gill; Cx, coxa; Cxrpd, coxopodite; Endp, endopodite; Eppd, epipodite; Expd, exopodite; Scx, subcoxa; rTr, first trochanter. : walls of the body segments, which unite to form the definitive leg bases and the pleural sclerites of the adult. Though the apparent facts in the development of the chilopods may be as Becker describes them, it is difficult to see how they can be interpreted literally as repre- 12 “ SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 senting the phylogenetic origin of the definitive pleural plates and the leg bases. It would seem more probable that they are ontogenetic phe- nomena only, and that Becker’s observations really show simply that the pleurites and the bases of the legs have a common origin. In the decapod crustaceans the inner walls of the gill chambers, which are covered externally by lateral folds of the carapace, are formed of large cuticular plates bearing the gills (fig. 7 D). Each plate, or pleuron, shows subdivisions (Sca4-Scxg) corresponding with the body segments of the ambulatory legs, and each subdivision bears a gill (Brn4-Brng). In the second maxilliped (B) the homologue of the gill is borne on an epipodite (Eppd) which is distinctly carried by / N A cx. Stn Ist B Fic. 8—A body segment of Strigamia bothriopus (Chilopoda, Geophilidae). A, lateral view, with leg removed beyond the coxa. B, ventral view, including bases of legs. Cx, coxa; /st, intersternite; pl, pleurites between the tergum and the subcoxa; Scr, subcoxa; Sp, spiracle; Stn, primary sternite; 7, tergum; Tr, trochanter. the basal segment of the appendage, or coxopodite (Cxpd). In the third maxilliped (C), however, the gill arises from a subcoxal part of the limb basis (Sc). In the ambulatory region (D) the gills on the pleuron are successively more and more removed from the coxae. It thus becomes evident that the pleural wall of the branchial chamber in the decapod crustaceans has been formed from dorsal extensions of the subcoxal parts of the leg bases, and that the coxae have acquired special articulations with the subcoxae. In the majority of crustaceans the leg base is an undivided coxopodite. In the Chilopoda there is a definitely circumscribed subcoxal area about the base of each leg, which may be continuously sclerotized, as in Strigamia (fig. 8 A, Scx), or which may contain one or more sclerites, as in Lithobius (fig. 9), Scolopendra, or Scutigera (fig. 10). The coxa is usually articulated to a sclerotized part of the subcoxa dorsally (fig. 10 A, c), or ventrally (figs. 9, 15, d) ; but since the axis NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 13 Fic. 9—A body segment and leg of Lithobius (Chilopoda), left side. c, dorsal articular point of coxa; Cx, coxa; d, ventral articulation of coxa with subcoxa; Fm, femur; Ptar, pretarsus; S, sternum; Scr, subcoxa; Sp, spiracle ; T, tergum; Tar, tarsus; Tb, tibia; 1Tr, first trochanter ; 2Tr, second trochanter. Fic. 10.—The leg base of Scutigera forceps (Chilopoda). A, external view of base of a left leg and part of segment. B, internal view of base of right leg, showing muscles. c, dorsal subcoxo-coxal articulation; cpl, supra-coxal plate of subcoxa; Cx, coxa; Fu, furca; J, tergal promotor muscles; J, tergal remotor muscle; K, sternal promotor; L, sternal remotor; M, subcoxo-coxal muscle; N, sternal adductor of coxa; N’, furcal adductor of coxa; Scx, subcoxa; Stn, segmental sternite; 7, tergum; 17,Y, first trochanter. I4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 of movement in the coxa is always between its dorsal and ventral angles, we may presume that the chilopod coxa has had both a dorsal and a ventral articulation with the subcoxa (fig. 1, c, d), though one or the other, or both of the articulations (fig. 8) may lose the struc- ture of definite articulating surfaces. In the geophilid Strigamia bothriopus (fig. 8) the subcoxal area of the pleuron has the form of a complete basal limb segment (A, Scr), though its ventral margin is expanded and united with the sternum (B), and the coxa turns upon it by an obliquely vertical axis. In Scolopendra, Lithobius (fig. 9), and Scutigera (fig. 10) the subcoxal area is mostly membranous, but it contains one or more well-sclerotized plates. The tergal muscles of the leg bases in the Chilopoda are inserted not on the coxae but on the subcoxae. In Scutigera the tergo-subcoxal muscles are strongly developed, those of each leg comprising a pair of anterior (promotor) muscles (fig. 10 B, J) inserted upon the dorsal plate (coxopleure, cpl) of the subcoxal region, and a single large posterior (remotor) muscle (J) inserted on the posterior dorsal mar- gin of the subcoxal region. The structure and musculature of the subcoxal region in the Chilopoda can leave little doubt that this area is the true base of the leg, which has become flattened into the lateral body wall, where, in most forms, its sclerotization has been more or less broken up and reduced. The sternal muscles of the leg base in the chilopods have gone over to the ventral rim of the coxa (fig. 10 B). They include an anterior (ventral promotor) muscle (A) and a posterior (ventral remotor) muscle (L). In Scutigera (fig. 10) the first of these mus- cles arises in the anterior lateral angle of the sternum, but in Scolopen- dra the corresponding muscle arises mesally on the anterior half of the sternum. The fibers of the posterior muscle in Scutigera (fig. 10 B, L) are mostly continuous from one coxa to the other, but a small anterior group on each side arises on the sternum at the base of the ligamentous endosternal furca (Fu). In Scutigera the coxa has no ventral articulation with the subcoxa or the sternum, but in those chilopods in which a ventral subcoxo-coxal articulation is present, the anterior and posterior ventral muscles (K, L) must act as promotors and remotors. The base of the coxa in the Chilopoda is provided also with median dorsal and ventral muscle. The dorsal median muscle in Scutigera (fig. 10 B, M) consists of a flat band of short fibers arising on the dorsal plate of the subcoxa (cpl), and is inserted on the rim of the coxa just behind the dorsal articulation with the subcoxa. This muscle NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 15 appears to be a remotor of the coxa in Scutigera, though it may have an abductor function also. The ventral median muscles of Scutigera comprise two bundles of fibers, one arising medially on the sternum (fig. 10 B, NV’), the other (.N’) arising on the lateral arm of the en- dosternal furca. These muscles are coxal adductors since the coxa has no fixed ventral articulation in Scutigera. The ventral coxal mus-~ cles are covered dorsally by large bands of trochanteral muscles that take their origin on the sternum. Fic. 11.—Diagram of the basal musculature of an insect leg. Bs, basisternum; Cx, coxa; J, tergal promotor muscle; J, tergal remotor; K, sternal promotor (anterior rotator); k, furcal suture; L, sternal remotor (posterior rotator) ; M, abductor of the coxa; M’, M”, abductors of the coxa that become the basalar and subalar muscles in the wing-bearing segments of adult insects; N, adductor of the coxa; SA, sternal apophysis; Scr, subcoxa; SI, sternellum; T, tergum; Tn, trochantin. In the insects the sclerotic areas of the subcoxae of the legs evi- dently become the pleural plates of the thoracic segments. The tergal promotor muscle of the leg base (fig. 11, /) retains its connection with the subcoxa in the more generalized pterygote insects, being inserted on the trochantinal sclerite of the subcoxa (Tn) except when the trochantin is lost, the muscle then having its insertion on the anterior angle of the coxal base. The remotor muscle (/), which may be repre- sented by several fiber bundles, is always inserted on the coxa or on coxal apodemes. The anterior and posterior sternal muscles (K, L) arise on the sterna or the sternal apophysis, or on the spinasteraum. 16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The median coxal muscles are represented in insects by both dorsal (MM) and ventral (NV) fibers. In the wing-bearing segments of ptery- gote insects the first comprise three distinct groups of abductor fibers (M, M’', M”) arising dorsally on the pleuron, and inserted ventrally on the coxa both anterior and posterior to the dorsal articulation of the latter (c). The second and third muscles of this group (/’, M”) Fic. 12.—Thoracic pleural sclerites of Apterygota. A, lateral view of left side of mesothorax of Acerentomon doderoit (from Berlese, 1910). B, thorax, base of head, and base of abdomen of Jsotoma sp. (from Ewing, 1928). C, left mesothoracic leg turned forward, and lateral re- gion of mesothorax of Acerentulus barberi (from Ewing, 1928). c, dorsal articulation of coxa; Cx, coxa; d, ventral articulation of coxa; Fm, femur; H, head; JT, JIT, first and second abdominal terga; Ptar, pretarsus; S, sternum; Scr, subcoxa; 7:, Tz, Ts, thoracic terga; Tar, tarsus; Tb, tibia; Tr, trochanter. become wing muscles in the adult by the partial or complete detach- ment of the epipleural areas on which they arise to form the basalar and subalar plates of the wing base. The ventral median muscle of the coxa (N) is present in insects that lack a ventral coxal articulation ; it arises on the sternal apophysis and functions as a coxal adductor. In the Apterygota the subcoxa becomes rudimentary. In most of the Protura its sclerotization is reduced to two slender plates arched concentrically over the base of the coxa (fig. 12 A, C, Sc+), as shown by Berlese (1910) and by Ewing (1928), though Prell (1913) has NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS Wf described the pleural sclerotizations of Eosentomon germanicum as consisting of a number of small sclerites, which, however, fall into two concentric series. (See Snodgrass, 1927, fig. 8.) In the Collem- bola, as shown by Ewing (1928), the subcoxal sclerotizations of the mesothorax and metathorax (fig. 12 B, Sc2, Scv3) consist in each segment of two slender, supra-coxal arches ; the subcoxal sclerotiza- tion of the prothorax (Scx,) is a single plate with an incomplete sub- division. In the Thysanura the subcoxal pleurites likewise take the form of two arches over the coxal base, or they become reduced to a single sclerite. The coxal and subcoxal musculature of the Aptery- gota has been but little studied. In the thoracic segments of the Pterygota the subcoxae evidently become the sclerotized parts of the lateral segmental walls known as the pleura (cf. figs. 1 and 13). The ventral rim of each subcoxa, lying between the coxa and the sternum (fig. 13 A), may be reduced to a membranous fold, though in rare cases it contains a large plate (fig. 17, Ls2, Ls;), and in others a rudimentary sclerite (fig. 16 A, Ls). In the majority of insects, as has been shown by Weber (1928, 1928 a), the ventral arc of the subcoxa has apparently fused with the primary sternite to form a laterosternite of the definitive sternum (figs. 13 B, TOO). Hes). The coxa of insects is universally hinged to the subcoxa by a dorsal articulation (fig. I, c) ; it may also have either an anterior articulation with the trochantinal piece of the subcoxa (fig. 13 B, e), or a ventral articulation (A, d) with the ventral rim of the subcoxa or with the subcoxal laterosternite. The trochantinal articulation of the coxa is peculiar to certain insects and is, therefore, probably a secondary one. The ventral articulation, however, so frequently recurs both in the Chilopoda (fig. 15, d) and in the more generalized insects (fig. 16 A, B, d) that there can be little doubt that the primitive axis of the subcoxo-coxal hinge was vertical or approximately so. The writer, therefore, would retract the opinion, expressed in a former study of the thorax (1927, pp. 34-36), that the primitive axis of the coxal movement was a horizontal one between anterior and posterior articu- lations with the eutrochantinal arch of the subcoxa. The ventral ar- ticulation of the coxa is highly variable in insects ; it is always absent in the more generalized Pterygota that have a well-developed trochan- tin. In the members of the higher orders lacking a trochantin it is commonly present, but it is to be suspected in such cases that the articulation is a secondary one developed between the coxa and the sternum. 2 18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The usual trochantin of the pterygote pleuron (fig. 13 B, Tm) is clearly a remnant of a more extensive, primitive, supra-coxal scleroti- zation (fig. 1, Eutn) carrying the dorsal articulation of the coxa (c), which Crampton (1914) has named the eutrochantin, and which is best preserved in the ventral arch of the apterygote pleuron (fig. 12). The eutrochantin is retained as an independent sclerite also in the prothorax of the Plecoptera, but in all other Pterygota (fig. 13, Pe acs Ble Pe acs “a / SS / / : \ , / \ aml EX Ist Stn $a lst B Ps TES itera Ss¢Ist) Fic. 13.—Diagrams suggesting the development of the pterygote pleuron from the subcoxa of the leg basis. (Compare with Fig. 1.) A, subcoxal sclerotization (Sc) united ventrally with edge of primary ster- nite (Stn), its dorsal extremity prolonged upward as a wing support (B, WP), posterior part of entrochantin (fig. 1, Eutn) fused with eupleural arch (fig. 1, Eupl) of subcoxa. B, a fundamental structural condition of pleuro-sternal region of a wing- bearing segment: the area of subcoxa differentiated into an episternum (Eps), an epimeron (Epm), a precoxal bridge (Acx), a postcoxal bridge (Pcx), a laterosternite (Ls), and a trochantin (Tn); the definitive sternum includes the primary segmental sternite (Stn), the following intersegmental intersternite, or spinasternite (S's), and a subcoxal laterosternite (Ls) on each side; the ventral coxal articulation (A, d) is lost, and coxa has a secondary anterior articulation with trochantin (¢). A, B) its dorsal and posterior parts unite or fuse with the upper arch of the pleuron (eupleuron), and only its anterior part remains as a free sclerite (fig. 13 B, Tm) carrying the anterior coxal articula- tion (e). The elaborate pterygote pleuron has evidently been developed to give support to the paranotal lobes, or to the wings evolved from the latter. It is therefore strengthened by an internal ridge formed from a linear inflection of its wall, the pleural suture (fig. 13 A, PIS), ex- tending from the dorsal articulation of the coxa (c) upward to the wing support (B, WP). The area lying posterior to the pleural suture is the epimeron (B, Epm), that situated anterior to it and dorsal to NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 19 the trochantin is the episternum (Eps). The sclerotized parts of the subcoxa lying anterior and posterior to the coxa are the precoxal and postcoxal bridges (Acx, Pcx), or precoxalia and postcoxalia. The ventral wall, or infra-coxal arc, of the subcoxa, as already noted, prob- ably unites in many cases with the edge of the primary sternum (Stn) to form a laterosternal element (Ls) in the definitive sternum, though it may be reduced to a separate sclerite or form a membranous fold between the coxa and the sternum. All parts of the pleuron are subject to innumerable secondary modi- fications taking the form of sutures that subdivide the primary areas, or of membranous lines and spaces that break them up into separate sclerites. Such modifications are not necessarily homologous between different orders, but within an order or group of orders they may give valuable evidence of the evolution and interrelationships of the fami- lies and genera. An example of this is given by Shepard (1930) in a study of the secondary pleural sutures of Lepidoptera. In the wing-bearing segments of the Pterygota two large pleuro- coxal muscles (fig. 11, M’, MM”) become important muscles of the wings. These muscles evidently are derived from the abductor system of the coxa. In nymphal Orthoptera (fig. 27 C) the anterior muscle (M’) has its origin on the dorsal part of the episternum, the posterior muscle (.4”) on the dorsal edge of the epimeron. In adult insects, however, the areas upon which these muscles are attached become par- tially or entirely separated from the pleuron and intimately associated with the base of the wing, the first lying before the pleural wing process, the second behind it. In this way the muscles come to func- tion as wing muscles, though each retains its ventral attachment on the coxa. The epipleurites (“‘ paraptera’’), or sclerites detached from the pleuron in connection with the coxo-alar muscles, include one or two episternal sclerites, or basalares, and usually a single epimeral sclerite, or subalare. The subalare is always completely detached from the epimeron in adult insects (fig. 14 A, B, Sa). A basalar plate, how- ever, is not always present as a distinct sclerite ; it frequently occurs as but an imperfectly separated lobe of the upper end of the episternum (fig. 14, Ba), and its area is sometimes marked only by the insertion of the anterior coxo-alar muscle (/’). Even when the basalare is dis- tinct from the episternum, it is generally hinged to the upper edge of the latter in such a manner that it is deflected by the contraction of its muscle. Frequently there is present a second basalar muscle (figs. 27 C, E) having its origin on the pleuron or on the sternum. 20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The theory of the origin of the principal pleural sclerites of the Chilopoda and Hexapoda from subcoxal segments of the legs has much in its favor. There is little evidence, however, that a subcoxa is a primary segment in the general arthropod appendage. The limb bases of the Arachnida, Xiphosura, and most Crustacea are the primi- tive coxae (coxopodites), for there can be no doubt of the identity of the coxo-trochanteral articulation in all arthropods. The writer Fic. 14.—The mesopleuron and base of the middle leg of a scorpion fly, Panorpa consuetudims. A, external view. B, internal view, showing muscles. a, accessory sclerite of basalar lobe; Ba, basalar lobe of episternum; bcs, basicostal suture of coxa; Bex, basicoxite; Cx, coxa; Epm, epimeron; Eps, episternum; MM’, basalar muscle; M”, subalar muscle; Mer, meron; O, levator muscle of trochanter ; PIS, pleural suture; Sa, subalar sclerite; W”7P, pleural wing process. clearly was mistaken in suggesting in a former paper (1927, p. 33) that the large basal leg segments of the ticks (Ixodoidea) are sub- coxal ; and he now believes that the segmentation of the arachnid limb can be given an interpretation different from that proposed by Ewing (1928), who would make the basal segment in most cases a subcoxa. In the decapod crustaceans the inner walls of the gill chambers, as has already been pointed out, are evidently expansions of the subcoxal regions of the bases of the ambulatory legs, to which the coxae of the latter have become articulated ; but there is no evidence of the pres- ence of subcoxal segments in the limbs of the more generalized Crus- tacea. In the myriapods and insects, moreover, as the writer has else- NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 21 where shown (1928), there are no true subcoxal segments in the mouth part appendages. From the evidence at hand, therefore, it ap- pears most in accord with the known facts to conclude that the subcoxa, wherever it occurs as a basal leg segment, has been produced by a secondary subdivision in the primitwe limb basis, or coxopodite. THE THORACIC STERNA Sternal plates are by no means so constant a feature in the scleroti- zation of arthropod segments as are the tergal plates. They may be present or absent within the same major group, and, where present, Fic. 15.—Sternites and leg bases of two consecutive segments of Lithobius (Chilopoda). Cx, coxa; d, ventral subcoxo-coxal articulation; Jst, intersternite; Scx, sub- coxa; Stn, segmental sternite; r7r, first trochanter; 277, second trochanter. they are often highly variable both in form and extent of development between closely related groups and in the different body regions of almost any species. In adult insects the sternal mechanism of the thorax differs in three important respects from that of the abdomen, and the functional dif- ferences in the two body regions are reflected as three distinctive struc- tural features in the sternal parts. The first distinction to be noted in the sternal structure, as between the thorax and the abdomen, pertains to the segmental relations of the intersegmental sternites. In the abdomen of adult insects the inter- segmental sclerotizations of both the dorsum and the venter are con- tinuous with the segmental sclerotizations following, and the trans- verse inflections in the cuticula of the primary intersegmental regions, 22 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 on which the fibers of the longitudinal muscles are attached, become the antecostae of the definitive terga and sterna (fig. 3). In the thorax, on the other hand, the ventral intersegmental sclerotizations either remain as small, free sclerites (fig. 1, 7st), or they unite with the posterior parts of the segmental plates preceding. The interseg- mental sternites, or intersternites, of the thoracic region are the spinasternites (fig. 18 D, Ss), so-called because each usually bears a small median apodemal process, the spina (fig. 4). A spinaster- nite occurs typically between the prothorax and the mesothorax, and between the mesothorax and the metathorax; there is never a free spinasternite following the metasternum because the corresponding intersegmental element goes with the first abdominal sternum to form the antecosta of the latter, except where it is lost as a result of the degeneration of the first abdominal sternum. The first spinasternite is more commonly persistent than the second which is usually fused into the posterior part of the mesosternum, where it may become entirely obliterated. The second structural difference between the thoracic and abdomi- nal sterna accompanies the difference in the relations of the interseg- mental sclerites to the segmental plates, but is not necessarily corre- lated with it. It consists of a reversal in the overlapping of the sterna. The successive abdominal sterna overlap regularly in a posterior direc- tion, as do the terga of both the abdomen and the thorax (fig. 3). The sterna of the thorax, on the other hand, overlap anteriorly. The meta- thoracic sternum, therefore, stands as a dividing plate between the anteriorly overlapping sterna of the thorax and the posteriorly over- lapping sterna of the abdomen (fig. 3, S3). This reversal in the overlapping of the sternal plates as between the thorax and the abdomen is probably the oldest structural differentia- tion between the two regions of the body, for it is well shown in some of the Apterygota, particularly in Japyx, and is exhibited by all pterygote insects in which the thoracic sterna remain free from each other. It was probably, therefore, established when the thorax was first set apart as the locomotor center of the body, and has nothing to do with the development of the wings. Just what advantage accrues to the thoracic mechanism from the reversed relations of its sternal plates is not clear, but presumably it gives a better device for the movement of the legs or for the movement of the successive seg- mental plates on each other. The third distinction between the thorax and the abdomen occurs in adult pterygote insects, and pertains to the attachments of the ven- tral muscles. We have assumed that the primitive attachments of the NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 23 fibers of the longitudinal muscles are on the intersegmental folds or on intersegmental sclerotizations (figs. 2, 3). The dorsal muscles throughout the length of the body, and the ventral muscles of the abdomen are thus attached, except where the anterior ends of the fibers may have migrated to the segmental regions of the definitive terga and sterna. In the thorax of adult pterygote insects, however, most of the sternal muscles are stretched between paired apodemal processes of the segmental sternites (fig. 4, S41, SA2), except that the anterior- most fibers are inserted anteriorly on the head, while the posteriormost fibers extend into the abdomen. Only a few slender median muscles retain a connection with the intersternites (7Ss, 2Ss). The paired Eps pee Fic. 16.—Sternal structure of ephemerid and odonate nymphs. A, ventral surface of mesothorax, metathorax, and first abdominal segment of an ephemerid nymph, showing ventral articulations of coxae (d) with sub- coxal, laterosternal sclerites (Ls). B, ventral surface of neck and prothorax of an aeschnid nymph, showing direct articulation of coxae (d) with laterosternal parts (Ls) of the definitive sternum. apophyses of the thoracic sterna are the so-called furcal arms, which in the higher orders are united upon a common median base and here constitute a true furca. The anterior ends of the ventral muscle fibers, as we have noted, are attached on the back of the head. In orthopteroid insects the attach- ment is with the posterior arms of the tentorium (fig. 4, PT), but this condition is clearly a secondary one since the posterior tentorial arms are tergal apodemes. In many adult insects, and in most holometabo- lous larvae, the anterior ventral muscles are inserted on the posterior part of the head wall. Morison (1927) enumerates three pairs of prothoracic sternal muscles in the honeybee, all of which are attached anteriorly on the lateral occipital regions of the head. In the caterpil- lars the corresponding muscles are inserted on apodemes of the ventral margin of the foramen magnum. In all such cases the insertion points of the ventral head muscles must have acquired their present positions 24. SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 by a migration from the true sternal region of the last head segment, which is the membranous floor of the neck behind the base of the labium. The ventral muscles of the thorax retain apparently the primitive condition in the larvae of most holometabolous insects. In the cater- pillar, for example, the principal longitudinal ventral muscles consist of two wide bands of fibers lying to each side of the ventral nerve cord, extending through the entire length of the body, and attached regularly on the intersegmental folds as are the dorsal longitudinals. External to the dorsal and ventral intersegmental muscles of the cater- pillar there is an intricate complex of small muscles disposed in all directions against the wall of each segment. In certain larval forms, as in some Coleoptera, the attachment of the ventral body muscles shows a condition intermediate between the usual larval condition and that of the adult. In the larva of Dytiscus, for example, as shown by Speyer (1922), though most of the ventral thoracic muscles are intersegmental, being attached either to processes of the intersegmental folds or to transverse ligaments arising from the folds, some of the fibers extend between segmental furcal apo- physes, which are present on each primary sternal region of the thorax. The ventral muscle bands of the thorax are continued into the abdomen, some of the fibers of the first abdominal segment being attached anteriorly on the intersegmental fold behind the metathorax, others on the furcal arms of the metasternum. In the adult of Dytiscus (Bauer, 1910) all the ventral muscles of the thorax are interfurcal in their attachments, and none extends from the thorax into the abdomen. Ventral muscles from the thorax into the abdomen are absent in the adult stage of many pterygote insects (fig. 35), though they may be present in the larval or the nymphal stages. In the nymph of Psylla mali, according to Weber (1929), two bundles of fibers diverge from the base of the metafurca to the anterior edge of the second abdominal sternum, but these muscles, Weber says, are lost in the adult. In some insects, however, the ventral thoracico-abdominal muscles are present in the adult stage. They are well developed in the cock- roach (Blatta orientalis), comprising here three pairs, the first arising on the second spina, the second on a ligamentous bridge between the bases of the metasternal apophyses, the third on the apophyses, all of which are inserted posteriorly on the anterior margin of the second abdominal sternum. The fibers arising on the metapophyses form the anterior ends of the ventral longitudinal muscle bands of the abdomen. In Gryllus, Voss (1905) describes a median pair of muscles arising on the metafurca which branch posteriorly to the third, fourth, and NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 25 fifth abdominal sterna, and two lateral groups on each side which go to the parasternal plates of the second abdominal segment. In the Cicadidae ventral muscles extend from the metathorax to the second abdominal sternum. In the Tenthredinidae, according to Weber (1927), a pair of muscles extends from the metafurcal arms to the second sternum of the abdomen, and in the honeybee Morison (1927) describes two corresponding pairs of muscles going from the meta- furca to the anterior margin of the second abdominal segment. Inas- much as these muscles, which represent the ventral muscles of the first abdominal segment, have no connection with the first abdominal ster- num, it is evident, as Morison points out, that their insertions, normally on the intersegmental anterior edge of the first abdominal sternum, have been secondarily transferred to the furcal apophyses of the meta- thoracic sternum. In the Ephemerida, however, Durken (1907) records the presence of a pair of muscles attached anteriorly on the bases of the metasternal apophyses and posteriorly on the anterior margin of the first abdominal sternum. These muscles would appear to correspond with the furco-spinal muscles, which are present in the prothorax of the grasshopper (fig. 35, 61). Even a brief review of the comparative musculature of larval and adult holometabolous insects thus shows that there takes place during metamorphosis a rearrangement in the attachments of the ventral muscles of the thorax, and, in some cases, of those of the first abdomi- nal segment, as a result of which most of the persisting fibers lose their intersegmental connections and acquire segmental attachments on the furcal apophyses of the thoracic sternal plates. The larval condition of intersegmental muscle attachments is clearly a more primitive one than that of the adult. The adults of insects with incomplete metamorphosis resemble those of holometabolous forms in having the principal ventral muscles attached on the furcal arms. Therefore, we must suspect that the latter condition is one secondarily acquired in all pterygote insects, and that it has come about during the evolution of the thorax as a specialized locomotor region of the body. Since the transposition of the ventral muscles takes place in the prothorax as well as in the other two thoracic segments, we cannot attribute its inception to the development of the wings. As yet, how- ever, we may draw only tentative conclusions concerning the evolution of the ventral musculature of the thorax, since our knowledge of the nymphal muscles in hemimetabolous insects and of both the larval and adult muscles in the more generalized holometabolous forms is very incomplete ; but the facts known point strongly to the transformation suggested above. 26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 An alteration in the attachment of the ventral muscles similar to that which evidently has taken place in insects may be observed also in the Chilopoda, here between members of different families. In the Geophilidae and in Lithobius the ventral longitudinal muscles consist principally of two flat, widely-separated bands of fibers lying close against the body wall and inserted on intersegmental sclerotizations. Fic. 17.—Ventral view of the base of the prothorax, the mesothorax, the metathorax, and the base of the abdomen of the large South American embiid, Cylindrachaeta spegazzinii. d, ventral articulation of coxa with subcoxal laterosternite (Ls); k, furcal suture; J, secondary suture of mesosternum; Ls, laterosternite; 1S.:, anterior plate of mesosternum; 252, posterior plate of mesosternum (furcasternite) ; Ti, ventral fold of protergum. In Scolopendra and Scutigera, on the other hand, both the longitudinal ventral muscles and many other muscles of each segment are attached on two ligamentous supports that arise from the posterior parts of the segmental sternites. In Scolopendra each ligament has a separate origin on the sternum ; in Scutigera the two ligaments in each segment arise from a common base, forming thus a furca-like structure (fig. 10 B, Fu) suggesting that of the higher pterygote insects. It is scarcely possible that there is any genetic relation between the furcal apophyses of insects and the muscle-supporting structures of NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 27 Scolopendra and Scutigera, but it is clear that the muscle attachments have been altered by a transposition which is of a parallel nature in the two cases. In the Chilopoda the sternal plates are uniformly developed through- out the length of the body. In Strigamia, Lithobius, and Scolopendra there is a series of alternating segmental sternites (figs. 8 B, 15, Stn) and intersegmental intersternites (Ist). The intersternites are lacking in Scutigera; they are highly developed in the geophilid Strigamua bothriopus, where their lateral ends extend upward on the sides of the body between the subcoxae (fig. 8 A), but they are small and incon- spicuous in Lithobius (fig. 15). In both the geophilid and lithobiid as we have seen, the longitudinal ventral muscle bands have their at- tachments on the intersternites. The presence of alternating sternites and intersternites in the chilo- pods might suggest that this condition was the primitive one in in- sects, and that the intersternites (spinasternites) have remained free in the thoracic region or have united with the preceding sterna, while they have fused with the segmental sternites following in the abdomen. In the odonate larva shown at B of figure 16 there is a long interseg- mental sclerite (2/st) between the posternum (S,) and the mesoster- num suggestive of the intersternites of the Chilopoda, and the fold (Ist) in the ventral side of the neck (Cv), which bears the cervical sclerites laterally (cv), appears to be likewise an intersternite between the labial segment and the prothorax. In the Acrididae the spinaster- nite between the prothorax and mesothorax (fig. 21, Ss) is a well- formed plate attached to the prosternum (.S) ; that between the meso- thorax and metathorax is indistinguishably fused into the posterior border of the mesosternum, though the spina persists (fig. 31, 2S pm). In many insects the first spinasternite is a free sclerite, and in the Blat- tidae both the first and the second are distinct plates (fig. 19 A, Ps 25 Ss). The definitive thoracic sterna of most insects are undoubtedly com- posite structures. The first and second intersternites are usually con- tained in the posterior parts of the prosternum and mesosternum, respectively, or at least are closely associated with them, though the first frequently retains its independence. The ventral arcs of the sub- coxae contribute laterosternal elements in many insects. The evident union of the ventral rim of the subcoxa with the sternum has been noted in the Hemiptera (Heymons, 1899, Snodgrass, 1927), but Weber (1928, 1928a) has given ample reasons for believing that this fusion of subcoxal elements with the primary sternum has taken place in the majority of insects. The frequent ventral articulation of the 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 coxae with the lateral margins of the sternum in generalized insects (figs. 12 C, 16 B, d) is further evidence that the sternum in such cases includes the infracoxal parts of the subcoxae, especially since it is found that, where distinct subcoxal laterosternal sclerites exist (figs. 16 A, 17, Ls), the coxae articulate with these sclerites (d). It is difficult to find in the insects a good example of a simple pri- mary sternal plate, comparable with the sterna of the Chilopoda (fig. 15), that does not contain either the following intersternite or sub- coxal laterosternal elements, or both. In the mesothorax and meta- thorax of the ephemerid nymph shown in figure 16 A, the sterna (Sz, S;) may contain the intersternites, but the two small sclerites in each segment (Ls, Ls) that articulate between the sternum and the coxa on each side appear to be the only remnants of subcoxal lateroster- nites. In the large embiid Cylindrachaeta (fig. 17) laterosternal plates (Ls2, Ls3) likewise are distinct, though the intersternites are clearly united with the primary sternites. In the prothorax of the aeschnid larva shown in figure 16 B the intersternite (2/s¢) is independent of the sternum, but the laterosternites (Ls) are fused into the lateral sternal margins. These several forms make it clear that the definitive thoracic ster- num of insects is typically a compound plate. It consists of a primary sternite (fig. 18 A, B, Stn), to which may be added the succeeding intersternite (Ist), which becomes the spinasternum (C, D, Ss), and a pair of latcrosternites (D, Ls, Ls) derived from the ventral arcs of the adjoining subcoxae (B, C, Scr). The possession of paired apophyses, or furcal arms, is character- istic of the thoracic sterna of all pterygote insects. The apophyses arise from the sternal plates between the bases of the legs, and their outer ends are usually closely attached, either by fusion or by short muscle fibers, to the inner ends of the corresponding pleural apophyses. Weber (1928, 1928a) advances the view that the sternal apophyses are primarily invaginations formed on the line of union between the primary sternites and the subcoxal laterosternites. In some insects, however, in which there are laterosternal plates not united with the sterna (figs. 16 A, 17), the origins of the sternal apophyses (s@) are still well within the sternal margins; and in an aeschnid nymph (fig. 16 B) the apodemal invaginations (sa, sa) are removed from the apparent margins of the laterosternite sections (Ls) of the definitive sternum. From evidence of this nature the writer would regard the sternal apophyses as invaginations in the primary sternal plate itself (fig. 18 B, Stn), though there is much in favor of Weber’s view. The mesosternum of wingless females of the black aphis, Aphis fabae, NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 29 Weber (1928a) says, presents a case in which there can be no doubt that the furca arises at a point between the basisternite, the furcaster- nite, and the subcoxal laterosternite. In the higher insects the sternal apophyses approach each other in each segment and unite upon a common basis produced by a median Fic. 18.—Diagrams suggesting the theoretical evolution of a thoracic sternum. A, primitive condition in which the ventral sclerotization consists of alter- nating segmental sternites (Stn) and intersegmental intersternites (Jst); the leg basis (LB) is an undivided coxopodite. B, primary sternite marked by the pits (sa) of a pair of internal apophyses, intersternite (/st) by the pit (spn) of a median process, or spina; leg basis (A, LB) subsegmented into subcoxa (Scx) and coxa (Cx), articulated dorsally and ventrally (d). C, area of primary sternite (A, B, Stn) divided into basisternum (Bs) and sternellum (S7) by a furcal suture (k) forming an internal furcal ridge between bases of sternal apophyses; the following intersternite has become a spinaster- num (Ss) by union with segmental sternite; subcoxa (Scx) united ventrally with sternum. D, typical definitive sternum, composed of primary sternite (A, B, Stn), a pair of subcoxal laterosternites (Ls, Ls), and the spinasternite (Ss); area of pri- mary sternite divided into basisternum (Bs) and sternellum (S7) by the furcal suture (k), and with a narrow presternum (Ps) set off by a secondary presternal suture (7). inflection of the sternal wall. In this way is formed the typical, forked endosternal structure known as the furca, the evolution of which has been portrayed by Weber (1928). The part of the sternum bearing the furca lies between the coxae, and is usually much narrowed by comparison with the region of the sternum anterior to it. The definitive sternal plate, whether it includes subcoxal lateroster- nal elements and the following intersternite, or does not, is commonly subdivided into an anterior and a posterior region. Fundamentally the 30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 dividing line is a transverse inflection, or “ suture,” passing through the bases of the sternal apophyses (fig. 18 C, k). The inflection is usually strongly sclerotized, forming an internal ridge evidently de- signed to brace the sternum and to support the apophyses (figs. 21 B, 31, k) ; it sometimes remains weak, however, and establishes a line of flexibility in the sternum. In either case the sternum is demarked by the furcal ridge and its suture (k) into a prefurcal area (fig. 18 C, Bs) and into a postfurcal area (ST). The anterior region of the sternum has been variously named sternum, in a restricted sense, antesternum, mesosternum, basisternwm, eusternum, and sternannum; the second has been called sternellum, poststernum, metasternum, and furcasternum. There are objections to all but one of these terms. “‘Antesternum”’ and “ poststernum ”’ (Amans, 1885) are applicable in some cases, but there is often a pre- sternal piece before the “‘ antesternum,”’ and very commonly the inter- segmental spina-bearing plate forms an actual posternal element of the definitive sternum behind the “ poststernum.” “ Mesosternum ” and ‘““metasternum ”’ (Berlese, 1909) violate the priority of the segmental prefixes. “ Basisternum ” and “ furcasternum ”’ (Crampton, Ig0g) are misleading because the part designated by the first is not basal, and that bearing the second name does not always carry the furcal apophyses. “ Eusternum ”’ (Snodgrass, 1910) implies that the part so named is the “true ”’ sternum, which it is not. “ Sternannum”’ (Mac Gillivray, 1923) has no grammatical standing, so far as the writer can find. “ Sternellum ” (MacLeay, 1830) alone can be given a clean bill. Of the terms applied to the prefurcal area, however, “ basisternum ”’ ap- pears to be the least objectionable. In the present paper, therefore, the writer adopts the following terms for the principal divisions of the definitive sternum (fig. 18 D): presternum (Ps), basisternum (Bs), sternellum (S71), and spinasternum (Ss). The first three are secon- dary subdivisions of the primary segmental sternum; the fourth is the intersegmental intersternite. To the primary sternal region there may be added on each side a subcoxal laterosternite (Ls). The parts of the definitive thoracic sternum as described here fit exactly with the definitions of the sternal sclerites given by Weber (1928, pp. 250, 251), with the understanding that the term “ sternel- lum” is substituted for ‘‘ furcasternum,” and that the poststernite is the intersegmental spinasternite. This idea of the sternal composition differs from Crampton’s (1909) conception in that the fundamental transverse dividing line of the sternum is assumed to be the furcal suture (k) between the bases of the sternal apophyses, and not a divi- ‘ NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 31 sion anterior to the apophyses. A prefurcal division sometimes does occur (fig. 17, 7), but it is clearly of a secondary nature and is vari- ously produced. The furcal suture is subject to much diversity in form, being some- times produced forward and branched laterally, or curved posteriorly, thus giving a variety of structure to its apodemal ridge, and often obscuring the primary line of the sternal division. The form and size of the sternal plates are frequently altered by a variation in the extent of the ventral sclerotization in the different thoracic segments. In the Blattidae it is evident that a partial de- sclerotization of the sternal cuticula has produced the unusual shapes and relationships of the sternal sclerites of the thorax (fig. 19). The prosternum most nearly preserves the typical form (B). It comprises two median plates (A, Bs,, Sl,) separated by a transverse fold (k) across the sternal region, from which arise the prosternal apophyses (SA,). A comparison with the assumed generalized structure of a thoracic sternum (B) will easily suggest that the transverse fold is the furcal suture (#), and that the pattern of the prosternal plates (C) has been produced by suppression of sclerotization in the lateral fields of the sternal area. In the mesothorax of Blatta (A) the ventral sclero- tization is reduced to a pair of basisternal plates (Bs.), and a Y-shaped furca-bearing sclerite (S/.), the two separated by an ample mem- branous area. In the latter are remnants of the sternal fold (k) from which arise the sternal apophyses (SA.) at the ends of the sternellar arms. The diagram D shows more clearly the relation of the mesoster- nal structure in the roach to the fundamental sternal structure (B), and again suggests that the peculiar features of the thoracic sterna of the roach are results merely of a reduction in the extent of the sclero- tized areas. The metasternum of Blatta (A) is essentially the same as the mesosternum, but the sternal fold appears to be suppressed and the apophyses (S'A;) arise from the sternellum (S/,). In some insects a thoracic sternum may be divided into two parts by a suture that is quite independent of the furcal suture. A clear case of this is seen in the thorax of the large embiid Cylindrachaeta (fig. 17), where a suture (/) cuts the mesosternum into an anterior plate (1S) and a posterior plate (2S,). The second plate is marked by the usual furcal suture (k) and bears the furcal arms; it is a true furca- sternite. The metasternum has the usual structure, though the sternel- lum is reduced to a narrow band behind the furcal suture (2). Most entomologists have believed that the sternum of a thoracic segment of an insect is “ composed of ” two principal plates, and the 32 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 pattern of the sternal sclerites in the cockroach (fig. 19) has had much to do with establishing this idea, for students have not recognized that the separated plates here are products of sclerotic degeneration, and that the fundamental structure, as shown best in the prothorax, is the same as in insects with undivided thoracic sterna. While the Blattidae undoubtedly retain some relatively generalized structural sa A Fic. 19.—The thoracic sterna of a cockroach, Blatta orientalis. A, general view of the three thoracic sterna and their paired apophyses. B, diagram of typical structure of a sternum. C, diagram of prosternum of Blatta. D, diagram of mesosternum of Blatta. Bs, basisternum; JS, first abdominal sternum; k, furcal suture; SA, sternal apophysis; sa, external pit of sternal apophysis; S/, sternellum; spn, external pit of spina; Ss, spinasternum; S, segmental sternum. characters, they are in many respects highly specialized insects adapted to a particular kind of habitat, though to one almost universally dis- tributed. The flattening of the body has been accompanied by a struc- tural alteration in most of the under parts of the thorax, and there is every reason to believe that the sterna, covered as they are by the bases of the legs, have become largely membranized to allow of an inflection of their posterior parts. We should be on very unsafe ground, there- fore, if we take the fragmented condition of the sternal sclerotization NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 33 in the thorax of the roach as representative of the primitive structure of the thoracic sterna in insects. A search for a generalized thoracic sternum among all groups of insects, the writer believes, would reveal nowhere the thing sought for, because it does not exist. A study of the arthropods as a whole, how- ever, suggests that the original area or areas of sclerotization in the ventral region of each segment spread into a continuous plate between the leg bases. The thoracic sterna of insects have been variously modi- fied by the development of apodemal braces where rigidity is demanded, and by secondary divisions or by reductions in the areas of sclerotiza- tion where flexibility is important. This theory recommends itself by the fact that it permits all kinds of specific structures and sclerotic patterns to arise, and does not assume that homologies must exist where none can be established. If. THE THORACIC SKELETON OF DISSOSTEIRA The Carolina locust, Dissosteira carolina, is here used as the subject for a special study of the thorax and its mechanisms because it is an insect sufficiently large for work on internal structure and is readily obtained, and because its muscular system is simple and comparatively easy to dissect. The thorax of the Acrididae is by no means general- ized, but for this reason it offers a good test for the application of gen- eral principles to the solution of specific problems. The structural features of the thorax in the locust, however, are those common to all insects, and in the musculature there is almost no addition of special muscles such as are found in most of the higher insect orders and to some extent in the other orthopteran families. The thorax of the jumping Orthoptera is so distinctly divided into a prothorax and a pterothorax that it is scarcely to be regarded as a unit in the organization of the body. The box-like structure of the com- bined mesothorax and metathorax, the oblique slant of the pleurites of these segments, and the firm connection of the first abdominal seg- ment with the metathorax are characters evidently correlated with the development of the hind legs as saltatorial organs. THE CERVICAL SCLERITES The grasshopper ordinarily keeps its head retracted against the pro- thorax, in which position the insect appears to have no neck, for the ample neck membrane (fig. 20 B, Cv), as well as the back part of the head, is thus concealed within the projecting anterior rim of the pronotum. 3 34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The neck skeleton of Dissosteira consists of two pairs of small cervical sclerites situated ventro-laterally in the membranous walls of the neck (fig. 20 B, rcv, 2cv). The two sclerites of each pair in the grasshopper are closely hinged to each other, and form a bridge on each side between the head and the prothorax. The first sclerite (rcv) is an irregularly triangular plate articulating with the occipital con- dyle (fig. 32, g) of the posterior rim of the head, situated just above the base of the posterior tentorial arm (A, PT). Immediately behind its articulation this plate bears externally two small lobes that are conspicuous by their covering of short hairs. The second cervical sclerite (fig. 20, B, 2cv) is a slender bar articulating posteriorly with the anterior margin of the prothoracic episternum (Eps) just within the overlapping edge of the protergum. The two cervical sclerites of each pair are movably hinged to each other at an angle directed ven- trally. They are mostly concealed when the head is in the usual re- tracted position, but they form a small prominence of the neck pro- jecting just behind the base of the maxilla. The probable function and mechanism of the cervical sclerites will be described in connection with the account of the muscles inserted upon them. The lateral, muscle-bearing cervical sclerites are probably homolo- gous structures in all insects in which they occur. Dorsal and ventral neck plates are presnt in some insects, but they are variable in size and arrangement and are probably secondary sclerotizations of the neck membrane. THE PROTHORAX The prothorax of the grasshopper is a highly individualized segment of the body, for, though its posterior dorsal and lateral parts widely overlap the anterior part of the mesothorax, it is separated from the latter by an ample intersegmental membrane (fig. 20 B, Wb). The external parts of the prothorax comprise tergal, pleural, and sternal sclerites. The principal plate is the tergum, a large bonnet-like piece that covers the back and most of the sides of the segment (fig. 20 A, T). Only a corner of each pleuron shows externally: this is the small triangular lobe lying anteriorly between the base of the leg and the lower margin of the tergum (fig. 20 A, Eps). The rest of the pleuron is deeply invaginated within the lateral wall of the tergum (B, Eps). The prosternum consists of two sclerites in the ventral wall of the segment between the bases of the first legs (fig. 21 A, S, Ss), the anterior one connected by the precoxal bridges (dcx) with the pleura. The prothoracic legs appear to be inserted between the ster- num and the lower edges of the tergum, but the lateral connections of NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 35 the legs are really with the inflected pleura covered by the tergal ex- tensions. The procoxal cavities are “ open” behind, that is, there are no postcoxal sclerotizations. Lying before the coxa of each leg in the articular membrane of the leg base is a small trochantinal sclerite (fic. 20 A, Tn). The protergun.—The tergum of the prothorax, besides covering the back and sides of its own segment, projects posteriorly over the dorsum of the mesothorax in a wide, triangular lobe which fits between the bases of the folded front wings. The top of the tergal bonnet Fic. 20.—The prothoracic tergum and pleuron of Dissosteira carolina. A, outer view of left side. B, inner view of right side, showing episternum invaginated within the tergum. a, posterior edge of anterior fold of tergum; b, anterior edge of posterior fold (B, Rd) of tergum; c, d, e, the external vertical grooves or sutures of the ter- gum (A) forming the internal tergal ridges (B); f, g, h, 1, horizontal sutures and their ridges connecting the vertical sutures and ridges. (fig. 20 A, T) is cut by a deep transverse notch somewhat before the middle, and the part before the notch is compressed into a median ridge. Each lateral area of the protergum is marked by a number of grooves forming a definite pattern, and by two non-impressed lines. The first non-impressed line (fig. 20 A, a) lies near the anterior border of the tergum and runs parallel with it; the second (b) extends downward in a sinuous course just posterior to the dorsal tergal notch. These two lines mark the limits of the inner folds of the anterior and pos- terior inflections of the tergal wall (B, a, b). The grooves of the tergal surface (A, c-7) lie in the space between the two non-impressed lines. They have no significance in themselves, but it is important to note 36 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 their positions because they form ridges on the inner surface (B) which have definite relations to the muscle attachments of the proter- gum. The first (c) is a short curved line on the upper lateral part of the tergum ; the second (d) is a longer line extending from the back almost to the ventral margin of the tergum; the third (e) begins at the dorsal notch and reaches ventrally just before the second non- impressed line (b) to the middle of the side. Connecting the three vertical grooves are four short longitudinal grooves, one (f) lying be- tween the first and second vertical grooves (c, d), the other three (g, h, 7) between the second and third vertical grooves (d, e). A study of the inner surface of the tergum (fig. 20 B) will show the endoskeletal ridges (c-i) formed by the external grooves. There AWiaakis Fic. 21.—The prothoracic sternum and pleura of Dissosteira. A, ventral view of sternum and lower edges of pleura, showing the spina- sternum (Ss) united with the segmental sternal plate (S), the latter continuous with the episterna (Eps) by the antecoxal bridges (Acx). B, dorsal surface of ee ee bases of sternal apophyses (SA, SA) united by a furcal ridge (k). will also be noted the anterior and posterior inflections of the tergal walls. From the margin of the first inflection (a) the neck membrane (Cv) is reflected forward, and from the margin (0) of the posterior fold or reduplication (Rd) the intersegmental membrane (Mb) is reflected posteriorly to the mesothorax. The first spiracle (Sp2) is located in this membrane. The propleura—-We have already noted that each pleuron of the prothorax appears externally only as a small plate projecting from beneath the edge of the tergum anterior to the base of the leg (fig. 20 A, Eps). It is to be seen on the internal surface of either half of the seg- ment (B), however, that the pleural piece exposed externally is merely the lower anterior corner of a much larger triangular sclerite (B, Eps) extended upward within the lateral tergal wall by a deep inflec- tion of the tergo-pleural membrane. The posterior margin of the sclerite is turned inward, forming the pleural ridge, which gives off NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 37 the pleural arm (P/A) and ends ventrally in the articular process of the coxa (CxP). Behind the lower part of the pleural ridge is a small epimeral piece (Epm) fused with the lower border of the tergum and concealed just within the edge of the latter. The anterior ventral angle of the episternum is continuous through the precoxal bridge (Ac) with the anterior lateral angle of the prosternum (fig. 21 A). The prosternum.—The sternum of the prothorax in the grasshopper consists of two distinct plates (fig. 21 A, S, Ss) separated by a trans- verse suture. The anterior plate (S) is the larger and the more strongly sclerotized. It is continuous laterally with the precoxal bridges (Acx) from the episterna (Eps). The definitive sternal plate of the prothorax, then, evidently includes laterosternal elements derived from the pleura (subcoxae), but the true pleuro-sternal limits are entirely obliterated. The anterior rim of the sternum is set off as a narrow presternal strip (Ps) by a submarginal external suture (A, 7) and a corresponding internal ridge (B, 7). Posteriorly the first sternal plate is marked by a deep transverse groove which forms a strong ridge on its inner surface (fig. 21 B, k) between the bases of the sternal apophyses (B, SA, SA), which latter are indicated externally by a pair of pits (A, sa, sa). The first prosternal plate in the grass- hopper, therefore, is divided in the primitive fashion (fig. 18 C) into a basisternal and a sternellar region by the suture of a ridge connecting the bases of the apophyses. The prosternal apophyses are simple arms (fig. 21 B, SA) diverging dorsally and laterally. Their distal ends are solidly united with the corresponding pleural apophyses. The second prosternal plate (fig. 21, Ss) is a spinasternite, and is, therefore, the intersternite between the prothorax and the mesothorax which has become closely associated with the primary sternite of the prothorax. It is mostly overlapped by the anterior margin of the mesosternum. The spinasternite of Dissosteira is triangular in shape, and is marked by a deep median impression (fig. 21 A) which forms the spina internally (B, Spi). THE PTEROTHORAX The united mesothorax and metathorax of the grasshopper consti- tute a unit in the body mechanism. The pleural and sternal walls of the two segments are solidly united, forming a trough-like structure perforated only by the openings of the coxal cavities. The leaping force of the hind legs is thus applied to a rigid middle section of the body, which also bears the wings. The dorsum of this body section is covered by the mesothoracic and metathoracic terga, but these plates 38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 are freely attached to the upper pleural margins of the pterothoracic trough by the ample membranes of the wing bases, and they are mov- ably joined to each other. As we shall later see, the wing mechanism demands at least a limited freedom of movement in the wing-bearing terga. In the grasshopper the back plates of the pterothorax (figs. 22, 24) differ somewhat in shape and in details of form and proportion, but the two have the same essential structure. They are relatively small, and when the insect is at rest they are hidden beneath the folded wings. The pleurites are defined externally by distinct grooves (fig. 26) forming strong ridges internally (fig. 28), which slant posteriorly and downward in a manner to suggest that they serve thus to brace the pleural walls against the projectile force of the hind legs. The sterna of the wing-bearing segments are wide plates fused laterally with the pleura before the leg bases (fig. 30). The mesotergum.—tThe tergum of the mesothorax (fig. 22 A) isa rectangular plate ending posteriorly in a distinct, transverse fold (Rd), the extremities of which are continued into the posterior thickened margins, or axillary cords (Axc), of the wing bases. Close to the anterior margin of the tergum is a deep groove (acs). This is the antecostal suture, or primary intersegmental inflection which forms the antecosta of the internal surface of the definitive tergum (B, Ac). The antecosta bears laterally two wide, flat apodemal plates (1Ph) projecting into the cavity of the thorax (fig. 25), which are the first pair of thoracic phragmata. On the external surface of the mesotergum, two sutures (fig. 22 A, ps, ps) diverge laterally and posteriorly from the antecostal suture (acs). They form internally a pair of strong ridges (B, PR) extend- ing to the bases of the anterior wing processes (ANP). The large, ir- regular, triangular regions (A, Psc, Psc) forming the anterior lateral angles of the tergum, set off by the divergent sutures (ps, ps), con- stitute the prescutal areas of the tergum. In the metathorax the prescutal sutures do not meet the antecostal suture, and the lateral prescutal lobes are continuous by a narrow median bridge behind the antecostal suture (fig. 24). In some other Acrididae, as in Melanoplus, the continuity of the prescutal area is more pronounced. In other orthopteran families the prescutum is narrow, but in the Blattidae and Gryllidae there is a suggestion of its separation from the scutal area. In any case, however, the prescutum of the Orthoptera must be re- garded as a secondary differentiation of the anterior part of the tergum. Its lateral parts become most sharply defined in the mesotergum of the Acrididae by the strong development of the prescutal ridges (fig. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—-SNODGRASS 39 22 B, PR) that brace the anterior wing processes. Upon the irregular surfaces of the prescutal lobes are attached the tergo-sternal muscles which are the principal elevators of the wings. A prescutum similar to that of the Orthoptera occurs also in certain other insects, though very likely it may be an independent differen- tiation formed as an adaptation to similar demands. In many insects of the higher orders, however, such as the Hemiptera, Diptera, and Hymenoptera, a prescutal area of quite a different nature is set off in the anterior median part of the tergum by the development of two Fic. 22——The mesothoracic tergum of Dissosteira. A, dorsal surface. B, ventral surface. Ac, antecosta; acs, antecostal suture; ANP, anterior notal wing process; Aw, prealar arm of tergum; 14x, first axillary; 44x, fourth axillary; AxC, axillary cord; Em, lateral emargination of tergum; Mb, secondary intersegmental membranes; n, lobe of prescutum articulating with base of subcostal wing vein; 0, lobe of scutum articulating with posterior part of first axillary; Pc, precosta; 1Ph, first phragma; ps, pre- scutal suture; Psc, Psc, lateral prescutal areas; Rd, posterior reduplication of tergum; Scl, scutellum; Sct, principal part of scutum; sct, sct, posterior lateral subdivisions of scutum; s, s, secondary ridges of tergum; tg, tegular rudiment; VR, remnant of V-ridge of tergum. lateral ridges, the parapsidal gradients (fig. 5 B, PaR), which extend a varying distance posteriorly from the anterior tergal margin, and usually converge. These ridges and their sutures apparently lie in the scutal region of the tergum, for there is sometimes present a narrow transverse prescutal band anterior to their bases. Parapsidal ridges are absent in the Orthoptera. The area of the mesotergum of Dissosteira posterior to the ante- costal and prescutal sutures is differentiated topographically into a large anterior scutal region (fig. 22 A, Sct), a median, posterior, tri- angular scutellar region (Sc/), two small, lateral, posterior scutal re- gions (sct, sct), and a posteriormost, deflected marginal region (Rd). The structure here presented is quite different in appearance from that of a typical wing-bearing tergum (fig. 5 A) in which the surface 40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 is divided into scutal and scutellar areas (Sct, Scl) by the suture (vs) of an internal V-shaped ridge (B, VR), the arms of which are con- vergent forward from the posterior lateral angles of the tergum. In the Acrididae the V-shaped endotergal ridge (fig. 22 B, VR) is almost obliterated, and the tergum is braced by two secondary ridges, one on each side (s), that converge posteriorly from the posterior lateral margins of the scutal area and intercept the arms of the rudi- mentary V-ridge (VR). The altered structure of the acridid tergum Rd Fic. 23.—Diagram of the structure of a wing-bearing tergum of Acrididae. The prescutal suture (ps) is either continuous, or suppressed medially; the usual V-ridge and its suture (vs) are partially suppressed and subordinated to a secondary ridge of similar shape but having its arms (s, s) convergent posteriorly. may be expressed diagrammatically as in figure 23, where the sup- pressed suture (vs) of the obsolete V-ridge is crossed by the dominant suture (s) of a secondary ridge of similar shape but having its arms convergent posteriorly. Thus the scutum consists of a principal an- terior scutal area (Sct) and of two small postero-lateral scutal areas (sct, sct) ; and the scutellum is divided into a median scutellar area (Scl) and two lateral scutellar areas (scl, scl), including the posterior fold of the tergum (Fd). The evolution of this condition can be traced in other Orthoptera from the primary structure which occurs in the Blattidae. A similar modification has taken place in the mesotergum of Hemiptera and Coleoptera, producing the triangular elevated shield of the scutellum that lies between the bases of the folded wings. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 41 It is clear that the external “ divisions’”’ of the wing-bearing ter- gum are incidental to the development of the internal ridges, which are adaptations to the part the tergum plays in the mechanism for moving the wings. The old idea that the tergum is “ composed of ” sclerites gave undue emphasis to surface features. Though a study of the latter may have a value for descriptive purposes, the student must look to the internal characters for a true understanding of the skeleton of insects. There is no postscutellar plate in the mesothorax of the grasshopper. The posterior deflected margin of the scutellum ends in a narrow inter- segmental membrane (fig. 25, 2b) uniting the mesotergum with the anterior margin of the precosta of the metatergum. The tergum of the mesothorax of the grasshopper, therefore, is a typical dorsal plate of a secondary segment, comprising the primary segmental sclerotization and the preceding primary intersegmental sclerotization of the back. In the latter the primary intersegmental fold is marked by the antecosta (fig. 25, dc) and the antecostal suture (acs). The lateral margins of the mesotergum are very irregular (fig. 22). The wings are extended from the tergal edges between the middle of the prescutal borders and the posterior reduplication of the scutellum. Anterior to the wing bases the anterior angles of the tergum are ex- tended as short prealar arms (fig. 22 A, Aw) to which are articulated the dorsal processes of the first basalar plates (fig. 26, Ba). The lat- eral margin of the prescutal area forms posteriorly a small process bearing a socket-like surface (m) in which the base of the subcostal wing vein turns when the wing is flexed or extended. Posterior to this process the anterior angle of the scutum is produced to form the large anterior notal wing processes (ANP), which support the neck of the first axillary sclerite of the wing base (14). The inner edge of the first axillary bridges the lateral emargination of the tergum (Em) and articulates with a marginal lobe (0) behind the latter. There is no posterior notal wing process in the mesotergum of the grasshopper ; the fourth axillary (44), which is itself probably a detached piece of the tergal margin, articulates with the edge of the scutellum. The metatergum.—tThe tergal plate of the metathorax (fig. 24) is somewhat longer than that of the mesothorax, since it must support the wider bases of the hind wings; but in many respects it is more weakly developed than the mesotergum, there being extensive non- sclerotized areas in the posterior part of the scutal region. The precostal rim of the metatergum (fig. 24, Pc) is narrow, except medially where it forms a conspicuous lip before the deeply inflected 42 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 antecostal suture (acs). The prescutal ridges and their sutures (ps, ps) are much weaker than those of the mesotergum, but they are not confluent medially with the antecostal ridge and suture, and the lateral prescutal triangles (Psc, Psc) appear to be continuous across the back in a narrow, weakly sclerotized area deflected into the antecostal suture (acs). Fic. 24.—The metathoracic tergum and postnotal plate of Dissosteira. acs, antecostal suture; ANP, anterior notal wing process; 1A», first axillary, 4Ax, fourth axillary; AxC, axillary cord; Em, lateral emargination of tergum; n, prescutal lobe to which base of subcostal wing vein is attached; 0, tergal lobe to which posterior end of first axillary articulates; p, tergal arm supporting anal veins of wing (see fig. 47 B); Pc, precosta; 2Ph, second phragma: PNs, postnotum; ps, prescutal suture; Psc, prescutum; Fd, posterior fold of tergum (see fig. 25, Rds); s, s, sutures of secondary tergal ridges; Sci, scutellum; Sct, principal part of scutum; sct, sct, subdivisions of scutum. The surface features of the scutal and scutellar regions of the meta- tergum have even less relation to the generalized structure of a wing- bearing tergum than do those of the mesotergum, because the tergal ridges (fig. 23) are here almost completely suppressed, and the exter- nal characters are the result of secondary inflections which produce a topographical pattern quite independent of the primary divisions of the tergum (fig. 5). Most of the scutal region (fig. 24, Sct) and the NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 43 median triangle of the scutellar region (Sc/) are confluent in a large shield-shaped area that forms the principal part of the tergal plate. The depressed posterior lateral parts of the scutum (sct, sct) are cut transversely by the faintly-marked sutures (s, s) of the posteriorly convergent ridges, which are obsolete in the metatergum, though strongly developed on the mesotergum (fig. 22 B, s). The posterior marginal area of the metatergum (fig. 24, Rd), which is a part of the true scutellar region, is sharply inflected (fig. 25, Ad;) and is continu- ous with the greatly extended precosta of the first abdominal segment, which constitutes a postnotal plate of the metathorax (figs. 24, 25, PNs3). Ee Set, Sel, Rd Setz Sls acs Fic. 25.—Median longitudinal section of mesotergum, metatergum, and meta- thoracic postnotal plate of Dissosteira, showing the phragmatal lobes of the right side. Ac, antecosta; acs, antecostal suture; JT, first abdominal tergum; 1M/b, 2Mb, secondary intersegmental membranes; z7Ph, 2Ph, 3Ph, first, second, and third phragmata; PNs, postnotal plate of metathorax, or greatly enlarged precosta of first abdominal tergum; Fd, posterior reduplication of tergum; Sct, scutum; Scl, scutellum. The lateral margins of the metatergum present the same features as do those of the mesotergum. The posterior angle of each prescutal area projects as a small marginal process (fig. 24, n) which is con- nected with the head of the subcostal wing vein by a ligament-like thickening of the basal wing membrane; it does not articulate with the vein as in the mesothorax. The anterior notal wing process (ANP) is a flat lobe of the scutum, to which the first axillary (14x) is closely hinged. Behind the wing process is a deep emargination (Em) of the scutellum, posterior to which is a second lobe (0) articulating with the posterior end of the first axillary. The slender fourth axillary (4A) articulates with the extreme posterior angle of the lateral scu- tellar area (sct). Each extremity of the posterior marginal fold of the tergum (Id) gives off into the anal membrane of the wing a long arm (p) that supports the anal veins (fig. 47 B). 44 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 The pterothoracic pleura——The pleurites of each side of the meso- thorax and metathorax are firmly united to form continuous lateral walls of the pterothoracic region (fig. 26) in which the episterna and epimera (Eps, Epm) are distinct plates separated by oblique grooves sloping from above downward and posteriorly. The first principal groove is the pleural suture of the mesothorax (P/S:;), the second is the intersegmental line, the third is the pleural suture of the meta- thorax (P/S;). Each pleural suture terminates above in a large wing Aer ZS ee EAS / Za / \ \ / s, Tn Cx, 0 Se asAaue a Fic. 26—The pterothoracic pleura of Dissosteira. Ba, basalar sclerites; Cx, coxa; Epm, epimeron; Eps, episternum; Fs, base of hind femur; 7, prepectal suture; P/S, pleural suture; PN3:, lateral arm of metathoracic postnotum; Ppct, prepectus; r. pleuro-sternal suture; S, sternum; Sa, subalare; Sp, mesothoracic spiracle; Ss, metathoracic spiracle; Tn, tro- chantin; Tr, trochanter; 1” P, pleural wing process. process (WP:, WP:), and below in the pleural articulation of the coxa. The episternum of each segment (Eps:, Eps) is united ven- trally before the coxal cavity with the edge of the sternum, the line of union (7) in the adult insect being obsolete in the mesothorax, but distinct in the metathorax. In the nymph of Dissosteira and of other Acrididae (fig. 27 A) the ventral edge of the precoxal part of the pleuron in both the mesothorax and the metathorax is distinctly sepa- rated from the sternum ; in the nymph of Gryllus (B) a precoxal plate (Acx) is separated from the pleuron and intervenes between the episternum and the sternum. The episternum of the mesothorax of Dissosteira (fig. 26, Eps.) is marked anteriorly by a submarginal NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 45 suture (7) which is continuous through the anterior part of the meso- sternum (.S;) and sets off from the sternum and the two episterna a narrow anterior marginal piece, or prepectus (Ppct), which is analo- gous to the similar sclerite of the Ichneumonidae and some other Hymenoptera. To the posterior margin of the epimeron of the meta- thorax (Epm3) is attached the large lateral extension of the meta- thoracic postnotum (PN;). The two pairs of spiracles of the thorax are presumably the meso- thoracic spiracles and the metathoracic spiracles, each pair being dis- placed anteriorly. The first spiracle on each side (fig. 26, Sp.) is PIS Ve Fic. 27.—Pterothoracic pleura of orthopteran nymphs. A, pterothoracic pleura of an acridid nymph, showing laterosternal arms of pleura (Ls) separated from sterna (S2, Ss) by the pleuro-sternal sutures (r, 1). B, mesopleuron and coxa of young nymph of Gryllus assimilis, showing a dis- tinct precoxal sclerite (Acx) between episternum (Eps) and sternum (S). C, inner view of B, showing the basalar and subalar muscles of the nymph (M', M") attached dorsally on edges of episternum and epimeron, respectively. situated laterally in the intersegmental membrane between the pro- thorax and the mesothorax, where it is covered by the posterior fold of the protergum. The second spiracle (fig. 26, Sp;) appears in the adult to lie in the lower posterior angle of the mesepimeron (Epmz) just above the base of the middle leg, and anterior to the fold between the mesothorax and the metathorax (fig. 28), but in the nymph (fig. 27 A) it occurs in the intersegmental fold. The structural pattern of the internal surface of the pleural wall of the pterothorax (fig. 28) is a replica of that of the outer surface, except that the impressed lines of the latter are represented by ridges. Each pleural ridge (P/R2, PIR;), however, gives off from its lower end a large pleural arm, or pleural apophysis (P/A2, PIA;), that projects inward across the coxal cavity, where it is closely associated with the lateral arm of the corresponding sternal apophysis (fig. 31, 46 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 PIA, SA), and the two are connected by a dense mass of short muscle fibers (figs. 34, 35, 86, II5). Of particular interest in the pterothoracic pleuron are the epipleu- rites, or the small plates situated in the membranes below the bases of the wings (figs. 26, 28, 29, Ba, Sa). Upon these plates are inserted the principal so-called direct muscles of the wing mechanism. In the grasshopper there are three epipleurites in each segment, two (Ba) Ba pe Sa ee Fic. 28.—Inner surface of right pterothoracic pleura of Dissosteira, showing the endoskeletal features. Lettering as on figure 26, with the following additions: CP, pleural coxal process; P/A, pleural arm; P/R, pleural ridge. situated before the wing process and articulated to the episternum, and one (Sa) in the membrane behind the wing process and above the epimeron. The episternal epipleurites are distinguished as the basalares, or basalar sclerites (Ba), the epimeral epipleurite as the subalare or subalar sclerite (Sa). In most insects there is but a single basalare. In Dissosteira the basalar sclerites are freely hinged to the upper margin of the episternum before the wing process (fig. 29, 1Ba, 2Ba) so that they can be turned inward and downward by the muscle inserted on their inner faces (fig. 49, E, M’'). The function of the epipleurites in connection with the movement of the wings will be de- scribed in Section V. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 47 There can be little doubt that the epipleurites are derived from the upper parts of the pleura. In a nymphal orthopteron the muscles that are inserted on the epipleurites in the adult (fig. 49) are attached directly to the upper edges of the episternum and epimeron (fig. 27 C, M',M"). In many adult insects the basalare remains as an undetached lobe of the episternum (fig. 14 A, Ba). In the membranous corium at the base of each leg there is a small plate (fig. 26, 7) situated before the coxa and loosely attached by its lower end to the rim of the coxa. These scierites are evidently rem- nants of the trochantins (fig. 13 A, B, Tm) since they exactly cor- 2Ba es Ys \ —— PIR Epmg Fic. 29.—Upper edge of the metathoracic pleuron and epipleurites of Dissosteira, inner view. 1Ba, first basalare; 2Ba, second basalare; Epm, epimeron’; Eps, episternum ; Sa, subalare; WP, pleural wing process. respond with the small trochantin of the prothorax (fig. 20 A, Tn), which is identified as such by the attachment of the promotor leg muscle upon it (fig. 33 A, 62). The pterothoracic sterna.—The sternal plates of the mesothorax and metathorax are united in a broad plastron covering the ventral surface of the pterothorax, and continuous laterally, in the adult, with the pleura by a fusion with the precoxal parts of the latter (fig. 30 A). In the nymph of Dissosteira and of other Acrididae, as already noted, the pleural plates of the mesothorax and metathorax (fig. 27 A, Plo, Pls) are distinctly separate from the sterna (S»2, S3), and the pre- coxal part of each pleuron is extended ventrally and posteriorly as a slender arm (Ls, Ls) between the sternum and the coxal corium. These arms are clearly remnants of the infra-coxal arcs of the sub- 48 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 coxae (fig. 18 B). In the adult grasshopper they form the ventral rims of the coxal cavities, that of the mesothorax becoming a weakly sclerotized plate, that of the mesothorax a membranous fold. The definitive sterna of the pterothorax in the Acrididae, therefore, do not appear to contain subcoxal laterosternal elements as integral parts of their areas. In the adult of Dissosteira the pleuro-sternal suture (fig. 30 A, 7) is obsolete in the mesothorax anterior to the coxa, but remains distinct in the metathorax. Fic. 30.—Pterothoracic sterna and the base of the abdomen of Dissosteira. A, general view of pterothoracic sterna and first two abdominal sterna. B, diagram of probable structure of mesosternum. C, diagram of probable struc- ture of metasternum. D, diagram of structure of first abdominal sternum. acs, antecostal suture of first abdominal sternum; Bs, basisternum; C+, coxa; CaC, coxal cavity; JS, IJS, first and second abdominal sterna; j, prepectal suture; k, furcal suture; Pc, precosta; Ppct, prepectus; r, r, pleuro-sternal sutures ; sa, sa, roots of sternal apophyses; SJ, sternellum; ¢, t, infra-coxal lobes of metasternum. The mesosternum of Dissosteira is a broad plate (fig. 30 A, Bso, Sl2) bounded laterally by the obsolete lines of the pleuro-sternal sutures (vr) and the rims of the coxal cavities. Its anterior edge is slightly convex ; its posterior border is deeply emarginated to receive a median rectangular extension of the mesosternum (Bs;) which is dove-tailed into the mesosternal notch. A prominent transverse suture (k), which forms internally a ridge through the bases of the sternal apophyses and extends laterally toward the coxal cavities (fig. 31, k, k) 1s coin- cident with the posterior edge of the median part of the sternum and NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 49 contains the external impressions of the sternal apophyses (fig. 30 A, sa, sa). The suture, therefore, is the furcal suture of the mesoster- num, and the two postero-lateral, quadrate mesosternal lobes (Sls, SI,) lying laterad of the median projection of the metasternum must belong to the sternellar region of the mesosternum. A median pit (spn) opening just behind the furcal suture (k) marks the site of the internal spina (fig. 31, 2Spu), which normally is intersegmental be- tween the mesosternum and the metasternum, but which is here fused with the mesosternal furcal ridge (k). There can be no doubt, there- fore, that a part of the mesosternum normally intervening between the furcal ridge and the spinasternum, which is the median area of the mesosternellum (fig. 30 B, S/), has been obliterated in Dissosteira, and that the spinasternum itself has been reduced to little more than the base of the spina. The mesosternum of Dissosteira is thus to be analyzed into the same structural elements that are preserved in a less modified form in the prosternum. The sternellar region of the sternum (fig. 30 B, SJ, S7) has been cut into a pair of lateral lobes (A, SJz, Slz) by the suppres- sion of its median area, and the following spinasternum (B, Ss) has been reduced to the base of the spina (fig. 31, 2Spn), which is united with the furcal ridge (/). The endoskeletal features of the mesosternum consist principally of the strong furcal ridge (fig. 31, k, k) and the two sternal apophyses (SA, SA). The latter are broad, tapering plates arising from thick bases and extending laterally beneath the pleural apophyses, to which they are attached by short muscle fibers (figs. 34, 35, 6). Each has a triangular basal lobe directed forward. Anteriorly the mesosternum is marked by the sternal part of the prepectal ridge (fig. 31, 7) which cuts off a marginal presternal strip continuous laterally with the pre- episternal areas of the prepectus (figs 26, 30, Ppct). The metasternum of Dissosteira (fig. 30 A, Bs3) is wider than the mesosternum and is separated laterally by distinct sutures (r) from the precoxal parts of the metapleura. Its anterior margin, as just ob- served, is extended in a large, median, quadrate lobe which is dove- tailed between the scutellar lobes of the mesosternum. Its posterior edge is broadly emarginate to receive a corresponding extension of the first abdominal sternum (Pc). The median scutellar region of the metasternum, shown diagrammatically at C of figure 30, is suppressed in the same manner as is that of the mesosternum, and the suture of the transverse sternal ridge (#) is here also coincident with the transverse margin of the sternal notch; but the suture does not extend laterad of the apophyses (sa, sa), and the lateral sternellar lobes are, therefore, 4 50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 not set off by sutures as in the mesosternum. The small triangular plates (t, t) bordering the coxal cavities appear to be subdivisions of the sternellar lobes rather than subcoxal laterosternal pieces, since the ventral arms of the pleurites in the nymph (fig. 27 A, Ls) form only the membranous folds beneath the coxal cavities in the metathorax. There is no spina associated with the metasternum. Crampton (1918) says the spinal pit has disappeared from the metasternum, but he gives no evidence of its former existence. As we have seen, the intersternal sclerotization between the metasternum and the first ab- dominal sternum remains as an integral part of the latter, or disappears Fic. 31.—Inner surface of ventral pleuro-sternal region of mesothorax. Bs, basisternum; CrC2, coxal cavity; Epm, epimeron; Eps, episternum; Isg, intersegmental groove; 7, ridge of prepectal suture; k, furcal ridge; PIA, pleural arm; P/R, pleural ridge; PIS, pleural suture; Ppct, prepectus; Ss, an- terior part of metasternum; SA, sternal apophysis; S/, sternellum; 2S pn, second spina, united with furcal ridge of mesosternum. when the first abdominal sternum becomes rudimentary. In Dissosteira the ventral muscles of the first abdominal segment (fig. 35, JS) are attached anteriorly on a weakly developed ridge (Ac) which crosses the first abdominal sternum between the angles of the sternellar lobes of the metasternum. The line of this ridge appears externally as a faint transverse suture (fig. 30 A, D, acs). The ridge (fig. 35, Ac), therefore, is the antecosta of the first abdominal sternum, and the representative of the spinae of the prothoracic and metathoracic sterna. The median plate dovetailed into the metasternum (figs. 30 A, D, 35, Pc) is the enlarged precosta of the first abdominal sternum. It cor- responds exactly with the postnotal plate of the metathorax (fig. 25, PN;), which is an extension of the precosta of the first abdominal tergum. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 51 Il. THE THORACIC MUSCLES OF DISSOSTEIRA The evolution of insect structure has been largely an evolution of mechanisms made up of the cuticula and the muscles. Though the study of the insect skeleton will remain the most important branch of insect anatomy for purposes of taxonomic description, it is becoming evident that the morphology of the skeleton is not to be understood without a knowledge of the relations that exist between the cuticular modifications and the muscles. Systematists and anatomists have con- sumed much time and have occupied much printed space with discus- sions of homologies between sclerites, which, in many cases, are of little value because the fundamental structure of the parts in question has not been studied and because mechanical relationships have been entirely ignored. The time is at hand when we must understand in- sects as living creatures rather than as museum specimens. Morphol- ogy must become a basis for the study of function, including both the physiological processes by which the insect is maintained as a liv- ing thing, and the mechanisms by which it directs its bodily activities. A grasshopper furnishes a particularly good subject for the study of insect musculature. Not only are the individual muscles easily dis- tinguished in dissections, but the muscles present are principally those that are common to all generalized insects. Fresh specimens do not serve well for the purpose of muscle study, but after twenty-four hours’ immersion in 80 per cent alcohol the fiber bundles become more compact and are more readily seen as separate muscles. Since most of the insect’s muscles are arranged laterally, a median sagittal section of the body will give the best approach to the muscles for an initial examination ; but eventually it will be necessary to cut specimens into numerous pieces, for each muscle must be followed from one attach- ment to the other. Never accept a supposed observation for a fact until it is seen alike in at least two preparations—not that specimens differ, but that observations frequently do. It is customary in describing muscles to follow them from their origins (fixed ends) to their insertions (movable ends), but the mus- cles of insects are in general more easily studied by finding the inser- tion points first and then tracing the bundles of fibers out to their basal attachments. The origins of muscles are likely to vary more in different segments and in different species than are the insertions, and branched muscles are often confusing until their common parts or apodemes of insertion are determined. The student will find that the principal thoracic muscles of Dis- sosteira more nearly correspond with the description of the muscles of the field cricket, Liogryllus (Acheta) campestris, given by Carpen- 52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 tier (1923) than with the description of the muscles of Gryllus domes- ticus given by Voss (1905). The musculature of the cricket is in some respects more elaborate than that of the locust; but the extra fibers constitute small and apparently secondary muscles that are not defi- nitely repeated in insects generally. The account of the musculature of Gryllus pennsylvanicus given by DuPorte (1920) contains inaccura- cies, especially with regard to the muscles of the legs ; the leg muscles of Gryllus are in no essential way different from those of Dissosteira. No attempt will be made in this paper to homologize the muscles of Dissosteira with those of other insects, or to correlate them with the muscles described by other writers, since this would add too much to the size of the paper. The student, however, should consult the recent descriptions of the thoracic musculature of insects contained in the works of Bauer (1910, 1924, adult Dytiscus), Speyer (1922, 1924, larval Dytiscus), Carpentier (1923, Acheta campestris and Tachy- cinus asynamorus), Weber (1927, Tenthredinidae; 1924, 1928, Lepi- doptera ; 1928a, Aphis fabae; 1929, Psylla mali), and Morison (1927, Apis mellifera). Berlese’s (1909) review of the musculature of in- sects will need some revision in the light of more extensive compara- tive studies of insect muscles; but a general myology of insects can not yet be undertaken since we need more extensive information con- cerning such groups as Apterygota, Plecoptera, and Neuroptera. The terminology of insect musculature offers some difficulty for the reasons that in different species the number of muscles in a functional group is variable, the attachments may shift from one point to another, and the functions of muscles undoubtedly homologous are often changed as a consequence of altered relations in the skeletal parts. In the following description of the thoracic musculature of the grass- hopper individual muscles are designated numerically for convenience of reference only, and the series of numbers (46 to 139) follows the enumeration of the head muscles of Dissosteira given in a former paper by the writer (1928). Dissection of the thoracic muscles is simplified when the general plan of the segmental musculature is understood. The thoracic mus- cles of insects fall into a few major groups which, in a general way, are as follows: (1) dorsal body muscles ; (29 ventral body muscles; (3) tergo-sternal muscles; (4) special wing muscles; (5) pleuro-sternal muscles ; (6) coxal wing muscles ; (7) body leg muscles ; (8) muscles of the leg segments; (9) muscles of the spiracles. In addition there are the muscles of the neck plates, and often oblique, lateral interseg- mental muscles. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 53 MUSCLES OF THE NECK AND PROTHORAX The prothoracic and neck muscles of the grasshopper are best studied from the mesal plane of the body. They may be exposed by cutting into lateral halves a specimen that includes the back of the head, the prothorax, and the mesothorax. Before removing the alimentary canal, a branched muscle should be observed going from the side of the protergum to the crop and the gastric caeca, which is, | JEST ; ee Py) SA. Bs..53, 7S B Fic. 32.—Muscles of the neck of Dissosteira, right side, internal view. A, muscles extending between head and prothorax, omitting 52, 53, and 54, shown in B, inserted on first cervical sclerite. B, muscles of cervical sclerites. Bs,, basisternum of prothorax; c, first ridge of protergum; Cv, neck; Icv, first cervical sclerite; 2cv, second cervical sclerite; d, second ridge of protergum; e, third ridge of protergum; Eps, prothoracic episternum; Eps:, mesothoracic episternum; g, process of head articulating with first cervical sclerite; H, head; 1Ph, first phragma; PoR, postoccipital ridge of head; PT, base of posterior ten- torial arm; ed, posterior fold of protergum; SA, prosternal apophysis; 1Spn, first spina; Ss, spinasternum; 71, protergum. 46. Posterior protractor of the crop and gastric caeca (fig. 33 A) .— A slender, branched muscle arising on lateral surface of protergum from lower end of first tergal ridge (c) just before base of tergal pro- motor of coxa (62) ; branching posteriorly to lateral wall of crop and tips of gastric caeca. The alimentary canal and fat tissue should now be removed in order to expose the muscles in the side of the neck and prothorax, some of which extend from the mesothorax to the head. Functionally there are three groups of these muscles, namely, those that move the head, those that move the prothorax, and those that move the fore leg. 54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 It is impossible to determine, from an anatomical study alone, the individual action of the muscles attached on the back of the head and on the cervical sclerites (fig. 32 A, B), since their functions may vary according to whether opposed sets of them act together or as antagon- ists. It is evident that the dorsal muscles (fig. 32 A, 47, 48, 49) and the ventral muscles (55) may tilt the head up or down respectively by pulling on opposite sides of the fulcrum of the cervical sclerites (g), or also that they may turn the head laterally if both sets on either side act as antagonists to those of the other side, while, finally, if they all act together they would become retractors of the head. The dorsal muscles of the cervical sclerites (A, B, 50, 52, 52, 53) must be the pro- tractors of the head, since their combined pull would straighten the angles between the two sclerites of each pair and thus push the head forward. The oblique ventral muscles of the cervical sclerites (fig. 35, 54) would appear to be accessory to the lateral movement of the head. 47. First protergal muscle of the head (fig. 32 A).—A slender muscle arising dorsally on protergum ; inserted dorso-laterally on post- occipital ridge of head (PoR). 48. Second protergal muscle of the head (fig. 32 A)=—A larger muscle arising dorsally on third ridge (¢) of protergum; inserted with 47 on postoccipital ridge of head. 49. Longitudinal dorsal muscle of the neck and prothorax (fig. 32 A).—A broad muscle from first thoracic phragma (1P/) to post- occipital ridge of head just below 48. 50, 51. Cephalic muscles of the cervical sclerites (fig. 32 A, B).— Origins on postoccipital ridge below 49; both extend ventrally and posteriorly, the first (50) inserted on first cervical plate, the second (51) on second cervical plate. 52, 53. Protergal muscles of the cervical sclerites (fig. 32 B:).— Origins dorso-laterally on protergum at lower end of first tergal ridge (c) ; both extend ventrally and anteriorly, crossing internal to 50 and 51, to insertions on first cervical sclerite, the first muscle with a branch (52a) to articular process (g) of head. 54. Prosternal muscle of the first cervical sclerite (figs. 32 A, B, 33 C, 35).—A horizontal, diagonal muscle arising on prosternal apo- physis (figs. 32, 35); inserted anteriorly on first cervical sclerite of opposite side (figs. 32 B, 35), the right and left muscles crossing each other medially (fig. 35). . 55. First ventral longitudinal muscle (figs. 32 A, 33 A, 35).—A broad, flat muscle from base of posterior arm of tentorium to apophy- sis of prosternum (figs. 32 A, 35, SA). NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 55 56. Dorsal lateral neck muscle (fig. 32 A).—A band of slender fibers from first phragma (zPh) inserted on base of neck mem- brane (Cv). 57. Ventral lateral neck muscle (fig. 32 A, B)—A short, flat mus- cle from anterior edge of prothoracic episternum (F/s,), inserted on base of neck membrane (Cv). The prothorax is movable on the mesothorax by two oblique, lateral intersegmental muscles on each side (fig. 32 A, 58, 59), and by three pairs of ventral intersegmental muscles (figs. 32 A, 35, 60, 87, 88). 58. Tergo-pleural intersegmental muscle (fig. 32 A)—A broad muscle of several sections, attached anteriorly on protergum behind upper end of ridge d; extends posteriorly and ventrally to interseg- mental membrane just before upper end of mesepisternum (EF ps2). 59. Sterno-pleural intersegmental muscle (figs. 32 A, 33 A, 35).— Attached anteriorly on upper end of prosternal apophysis (figs. 32 A, 33 A, SA) ; extends posteriorly and dorsally to dorsal end of anterior margin of mesepisternum (Eps.). In some insects this muscle is at- tached posteriorly on the anterior angle of the mesotergum. 60. Second ventral longitudinal muscle (figs. 32 A, 33 A, 35).— Extends between prosternal and mesosternal apophyses. Attached anteriorly by broad base on prosternal apophysis ; tapers posteriorly to attachment on anterior margin of mesosternal apophysis (fig. 35). The other two sternal muscles that move the prothorax are the third and fourth ventral longitudinals (figs. 32 A, 35, 87, 88) attached an- teriorly on the first spina (7Spn), but they will be described with the mesothoracic muscles. | 6r. Sterno-spinal muscle (figs. 33 C, 35).—A very small muscle arising on base of prosternal apophysis (SA) ; the two from opposite sides converging posteriorly to insertions on anterior end of first spina (7Spn). Since the spinasternum (Ss) is but little movable on the prosternum (S,) in the grasshopper, this pair of muscles can act only as tensors or levators of the spinasternum. The muscles that move the prothoracic leg of Dissostetra represent the tergal promotor (fig. 11, J), the tergal remotor (J), and the sternal remotor (L) of the primitive limb base, and the abductors (M) and the adductors (N) of the coxa. A representative of the sternal promotor (K) is absent in the prothorax of Dissosteira. The sternal remotors function as posterior rotators of the coxa by reason of the single articulation of the latter with the pleuron only; in Dissosteira one branch of the sternal remotor arises on the spina. 50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 62. Tergal promotor of the coxa (fig. 33 A).—The largest muscle of the prothorax. Origin on upper lateral wall of protergum, posterior to lower end of first ridge (c) ; insertion ventrally on the small tro- chantin (fig. 33 A, B, D, Tn). 63. Furst tergal remotor of the coxa (fig. 33 A).—Origin on lateral wall of protergum mesad of upper end of 62 below ridge f; extends ventrally and posteriorly external to 59 and 60 to insertion on posterior angle of base of coxa (fig: 33 B, C, D). 64. Second tergal remotor of the coxa (fig. 33 A, B, C, D)—A short muscle arising on lateral wall of protergum (D) beneath ridge 7; insertion on posterior angle of coxa (C, D). 65. Third tergal remotor of the coxa (fig. 33 A, B, C, D).—A slender muscle arising on protergum (D) in angle between ridges e and h,; insertion ventrally on posterior angle of coxa. 66. First posterior rotator of the coxa (figs. 33 C, D, 35).—Origin on base of sternal apophysis (figs. 33 C, 35, SA) ; insertion on pos- terior angle of coxa. 67. Second posterior rotator of the coxa (figs. 33 C, D, 35).— Origin on side of spina (figs. 33 C, 35, 1S pm) ; insertion on posterior angle of coxa. 68. Abductor of the coxa (fig. 33, B, D).—A flat, two-branched muscle arising on inner face of episternum (Eps), the larger branch (68b) dorsally, the smaller branch (68a) in anterior ventral angle; both inserted by a common stalk on outer rim of coxa (D) just before pleural coxal articulation (C+P). 69. Adductor of the coxa (fig. 33 C).—Origin on outer end of sternal apophysis (SA), or at union of the latter with pleural apo- physis (P/A) ; insertion on inner rim of base of coxa (Cr). The following nine muscles (70 to 7S) pertain to the segments of the telopodite of the prothoracic leg. Three branches of the depressor of the trochanter (77) have their origins within the body. zo. Levator of the trochanter (fig. 36 A).—Origin dorsally in an- terior part of coxa; fibers converge to insertion on tendon arising from dorsal lip of base of trochanter. This is the lifting muscle of the telopodite. 71. Depressor of the trochanter (figs. 33 A, B, C, 36 A).—A five- branched muscle, two groups of fibers arising in the coxa and three in the prothorax, all converging upon a strong apodeme arising from ventral lip of base of trochanter (fig. 36 A, 77Ap). The coxal branches arise anteriorly (77a) and posteriorly in ventral part of coxa; of the three body branches the first (77D) arises dorsally on anterior margin NO. 2 .THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 57 / ae 1Spn 67 66 Fic. 33.—Musculature of the base of the fore leg of Dissosteira. A, inner view of base of right leg, showing coxal and trochanteral muscles arising on lateral walls of protergum; tergal ridges lettered as on figure 20 B. B, same as A but with inner muscles removed, showing coxal and_trochanteral muscles arising on episternum, and posterior group on tergum. C, posterior view of prosternum, right pleuron, and right coxa, showing leg muscles arising on sternum and pleural arm. D, articular region of base of right coxa, and associated muscles, inner view. 58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 of episternum (fig. 33 B, Eps), the second (77c) on ventral edge of pleural arm (fig. 33 C, PIA), the third (77d) on lateral wall of pro- tergum (fig. 33 A, B) just below ridge h. These groups of fibers con- stitute the most powerful muscle of the leg and function as the de- pressor of the telopodite as a whole. 72. Reductor of the femur (fig. 36 A).—A short, broad muscle in posterior part of trochanter (771) arising on ventral wall of the seg- ment; fibers extending dorsally and posteriorly to posterior rim of base of femur, giving the latter a slight posterior flexion. 73. Anterior levator of the tibia (fig. 36 A).—An extremely slen- der muscle arising anteriorly in base of femur; inserted by long, thread-like apodeme on a process from anterior side of base of tibia (as in middle leg, fig. 36 B, r05Ap). 74. Posterior levator of the tibia (fig. 36 A).—Origin dorsally in proximal part of femur; insertion by a strong tendon on posterior dorsal angle of base of tibia (as in middle leg, fig. 36 E, 106). 75. Depressor of the tibia (fig. 36 A).—Origin anteriorly (75a) and posteriorly on ventral wall of femur, with branch (75c) from base of trochanter (Tr) ; inserted by a strong tendinous apodeme aris- ing from small ventral plate in membrane of femoro-tibial joint. 76. Levator of the tarsus—Origin on distal third of dorsal wall of tibia; insertion on dorsal lip of base of tarsus. 77. Depressor of tarsus——Origin on ventral wall of tibia; inser- tion on ventral lip of base of tarsus. 78. Depressor of the pretarsus: retractor of the claws (fig. 36 A).— This muscle comprises three branches, the principal one arising pos- teriorly in base of femur (fig. 36 A, 78), the other two in upper part of tibia; all inserted on a long tendon extending from femur through tibia and tarsus to unguitractor plate at base of claws. The following two muscles are those of the first spiracle, but since the first spiracle is situated within the region of the prothorax, its muscles are to be classed as prothoracic. The mechanism of the spira- cles will be discussed in Section VI. 79. Closing muscle of the first spiracle (fig. 51 B).—Origin on ventral process of peritreme (/) ; insertion on lever of posterior lip of spiracle (7). 80. Opening muscle of the first spiracle (fig. 51 B).—Origin on ventral process of peritreme; insertion on base of posterior lip of spiracle. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 59 MUSCLES OF THE PTEROTHORAX The musculature of the wing-bearing segments differs in many respects from that of the prothorax, particularly in the great develop- ment of the dorsal longitudinal muscles (fig. 34, 87, 112), in the pres- ence of large tergo-sternal muscles (83, 84, 113) and special wing muscles which are lacking in the prothorax, and in the presence of two pleuro-coxal muscles that become wing muscles in the adult. The dorsal longitudinals and the tergo-sternals constitute a group known as the indirect wing muscles because they effect movements of Sete Scl, oe es Selz fs NO ane By Wye Sea Goher ina ea Fic. 34.—General view of the musculature in the right half of the pterothorax of Dissosteira. Median section, seen from the left. the wings by alternate changes in the curvature of the tergum. There is but one special wing muscle in Dissosteira connected with each wing : this is the wing flexor (figs. 37 A, 85; 49, D), a short muscle hav- ing its origin on the pleuron and its insertion on the third axillary sclerite of the wing base. In many insects there are several small muscles from the upper parts of the pleuron to the edge of the tergum or to the base of the wing, but representatives of these muscles are absent in the grasshopper. The two pleuro-coxal muscles that become important wing muscles in the adult are apparently abductors of the coxa in the nymph (fig. 27 C, M’, M”). The first is the pronator- 60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 extensor of the wing (fig. 49, M’), having its dorsal insertion on the basalar plates of the adult ; the second is the depressor-extensor (M”) with its insertions on the subalar plate. Associated with the first is a large muscle (£) arising ventrally on the sternum. These three epipleural muscles (E, M’, M”) together with the wing flexor (D) constitute the so-called direct wing muscles, though only the flexor is a true wing muscle. The ventral muscles of the pterothorax are small ; those of the meso- thorax (figs. 34, 35, 60, 87, 88) serve to move the prothorax ; those of the metathorax (176, 777) can have but little motor function, since the mesothorax and metathorax are immovable on each other, and they are reduced mostly to tendinous strands. The muscles of the mid- dle and hind legs are essentially the same as those of the prothoracic leg, but the muscles of the hind tibia are particularly large and not of the same relative size as those of the fore and middle legs. A first dissection of the pterothoracic musculature should be made from the median plane of the body in a specimen cut into lateral halves (fig. 34) from which the alimentary canal and other visceral tissues have been removed. THE MESOTHORACIC MUSCLES 81. Longitudinal dorsal muscles (fig. 34).—A large mass of fibers in each side of upper median part of mesothorax, attached anteriorly on lobes of first phragma (zPh) and posteriorly on middle phragma. 82. Oblique dorsal muscles (not shown in figures).—A small mus- cle laterad of longitudinal dorsals; arising on lateral part of scutum, extending posteriorly and ventrally to insertion on outer part of mid- dle phragma. 8&3. First tergo-sternal muscle (fig. 34.).—Attached dorsally on pos- terior part of lateral prescutal lobe ; attached ventrally on anterior part of mesosternum. 84. Second tergo-sternal muscle (fig. 34).—A very large muscle im- mediately posterior to §3; attached dorsally by inner branch on middle of lateral scutal area, and by outer branch on marginal lobe of scutum behind posterior articulation of first axillary; attached ventrally on mesosternum before inner margin of coxal cavity. 85. Pleuro-alar muscle: flexor of the wing (fig. 37 A).—This mus- cle lies laterad of the series of dorsoventral muscles in the side of the segment and may be noted after the latter are removed. It arises by a broad base on upper part of pleural ridge (PIR), and goes dorsally and posteriorly between 98 and 99 into wing base where it is inserted on the third axillary (fig. 49, 34%). NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 61 ZOU ZED fe | Fic. 35.—General view of the ventral musculature of Dissosteira from the head to the second abdominal segment. 62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 86. Pleuro-sternal muscle (figs. 34, 35).—A dense mass of very short fibers connecting the approximated ends of the pleural apophysis and the sternal apophysis. 87. Third ventral longitudinal muscle (figs. 34, 35)—Attached laterally on first spina (1Spm) ; extends posteriorly and laterally over posterior end of 60 to anterior edge of apophysis of mesosternum (S'A2). 88. Fourth ventral longitudinal muscle (figs. 34, 35).—A slender muscle attached anteriorly on first spina (1Spn) and posteriorly on second spina (2S pn). The following thirteen muscles (89-101) include the muscles of the base of the leg and the principal direct muscles of the wing. 89. Tergal promotor of the coxa (fig. 34).—Lies close behind &4 in the innermost series of lateral muscles. Origin on scutum; inser- tion on stalked disc (fig. 37 A, B, C, 89) arising from articular mem- brane at anterior angle of coxa close to lower end of trochantin (B, C, Tn). The representative of this muscle in the prothorax (fig. 33 A, 62) is inserted on the trochantin, as it is in most insects in which the trochantin is well developed. 90. First tergal remotor of the coxa (fig. 34).—Origin on scutum ; goes ventrally posterior to pleural arm to insertion on stalked disc arising from inner posterior angle of coxa (fig. 37 A, B, 90). o1. Second tergal remotor of the coxa (fig. 37 A).—A slender muscle arising on scutum from outer end of ridge s (fig. 22 B) ; goes obliquely ventrally and posteriorly to slender apodeme arising from extreme posterior angle of coxa (fig. 37 A, B, 91). This muscle is the last of the tergal muscles of the mesothorax ; it lies just external to posterior border of go and is partially visible from median plane (fig. 34.) between 9o and 173. The group of mesothoracic muscles attached dorsally on the tergum includes two segmental branches of the depressor of the trochanter (103) which will be described later. When the tergal muscles have been removed there is exposed a second or outer set of lateral muscles having their origin on the pleuron (fig. 37 A). These muscles include the abductors of the coxa, and the direct muscles of the wing. The wing flexor (85) of the latter group has already been described as a pleuro-alar muscle; the others are pleuro-coxal, with one pleuro- sternal muscle. Ventrally there will be seen also the sterno-coxal mus- cles, or rotators of the coxa, a description of which will logically fol- low that of the tergo-coxal muscles. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 63 Fic. 36.—Leg musculature of Dissosteira. A, posterior view of muscles in proximal part of right fore leg, including coxa (Cx), trochanter (77), and base of femur (Fim). B, anterior and ventral muscles of tibia arising in femur and trochanter of left middle leg. C, cross-section near middle of second left tibia, proximal surface of distal half, showing positions of tibial muscles. D, dorsal view of trochanter (77) of left hind leg, showing anterior and pos- terior coxo-trochanteral articulations (f, g), and levator muscles of trochanter arising in coxa. E, dorsal view of femoro-tibial joint of left middle leg, showing anterior and posterior articulations (J, mm), and bases of levator muscles of tibia. F, corresponding view of femoro-tibial joint of left hind leg. 64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 92. Anterior rotator of the coxa (figs. 34, 35, 37).—Origin on sternellar lobe of mesosternum (figs. 34, 35) ; extends anteriorly and outward to anterior angle of coxa (figs. 35, 37 A, B, C). 93. Posterior rotator of the coxa (figs. 34, 35, 37).—Origin on second spina (figs. 34, 35) ; extends outward, above 92, to posterior inner angle of coxa (figs. 35, 37 A, B). 04,95. First and second abductors of the coxa (fig. 37 A) —Origin on anterior ventral area of episternum (Eps) ; fibers of each converge to a pair of long, flat apodemes arising anteriorly on outer margin of coxa (fig. 37 B, C, 94, 95). 06. Third abductor of the coxa (fig. 37 A)—A wide, flat, fan- shaped muscle arising on episternal area posterior and dorsal to 95; fibers converging to insertion on a slender apodeme arising in articu- lar membrane laterad of base of coxa just anterior to pleural articu- lation (fig. 37 B, 96). 07. First pronator-extensor of the forewing (fig. 37 A).—A large muscle inserted dorsally on first basalar plate (7Ba) ; extending ven- trally to attachment on lateral part of sternum before base of mid- dle leg. 98. Second pronator-extensor of the forewing (fig. 37 A)— Insertion dorsally close to 97 on first basalar plate (1Ba) ; attached ventrally on bases of apodemes of first and second abductors of coxa (figs 337) B, G08): 99. Depressor-extensor of the forewing (fig. 37 A).—Inserted dor- sally on subalar plate of wing base (Sa) ; attached ventrally on flat extension of basicoxal ridge (fig. 37 B, 99) in meral region of coxa (Mer) posterior to pleural articulation (c). 100. First adductor of the coxa (fig. 37 A).—A broad flat muscle arising on posterior margin of mesosternal apophysis; insertion on inner rim of coxa (A, B, 100). ror. Second adductor of the coxa (fig. 37 A).—A smaller muscle arising on mesosternal apophysis ; inserted on posterior angle of coxa (A, B, ror) between attachments of 90 and 91. The telopodite of the middle leg, or that part of the limb beyond the coxa, has the same musculature as the telopodite of the first leg; its muscles are the following : 102. Levator of the trochanter——Origin dorsally in base of coxa; insertion on dorsal lip of base of trochanter. 103. Depressor of the trochanter.—-A five-branched muscle with all branches inserted on a tongue-like apodeme arising from ventral lip of base of trochanter. Two branches arise ventrally in the coxa, one NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 65 anteriorly, the other posteriorly; the others take their origin in the mesothorax. The first and second body branches arise on scutum, one medially the other on lateral margin, both pass into coxa anterior to pleural arm; the third body branch arises on ventral margin of meso- sternal apophysis. The trochantinal muscles effect the movement of the telopodite as a whole. 1Ba 2Ba WP, Sa at 95 Mer easy J ie | 99 91 \ AI ie | 98-1 me \ 96—-~ IA WN Fic. 37.—Coxal musculature of the middle leg of Dissosteira. A, general view of pleural muscles, right side, inner view, and bases of sternal coxal muscles. B, base of coxa, inner view, showing muscle attachments. C, anterior rim of coxa (Cx), trochantin (Tm), and attachments of associated muscles, inner view. 104. Reductor of the femur.—A sheet of very delicate fibers in posterior part of trochanter, arising in base of latter, inserted on pos- terior rim of base of femur. This muscle is much weaker than the corresponding muscle of the prothoracic leg (fig. 36 A, 72), the femur of the middle leg being scarcely movable on the trochanter. 105. Anterior levator of the tibia (fig. 36 B, C).—A delicate, at- tenuate muscle arising anteriorly in base of femur; inserted by a long tendon-like apodeme arising from dorsal end of a slender process from anterior margin of base of tibia (fig. 36 E, 105Ap). 5 66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 106. Posterior levator of the tibia (fig. 37 C, E).—A long, pinnate muscle with fibers arising on almost entire length of dorso-posterior wall of femur ; inserted by strap-like tendon on dorsal angle of base of tibia (E, 106). . 107. Depressor of the tibia (fig. 36 B, C)—The largest muscle in the middle femur, comprising three groups of fibers, all inserted on a long apodeme arising from small plate in ventral membrane of knee joint. Principal group of fibers (B, z07a) forms a long pinnate mus- cle arising ventrally in proximal part of femur; second group a small bundle of fibers (107b) arising in base of trochanter and joining with those of first group; fibers of third group (107c) arise anteriorly and dorsally in distal two-thirds of femur and converge ventrally to inser- tion on base of depressor apodeme. 108. Levator of the tarsus (fig. 42 A).—Origin dorsally in distal third of tibia ; insertion on dorsal lip of base of tarsus. tog. Depressor of the tarsus (fig. 42 A).—Origin ventrally in dis- tal three-fourths of tibia ; insertion on ventral lip of base of tarsus. 110. Depressor of the pretarsus: retractor of the claws (figs. 36 C, 42 A, C).—Fibers arising in femur and tibia ; inserted on long, thread- like apodeme arising from unguitractor plate at base of claws (fig. 42 C, 110Ap) and extending through tarsus (A) and tibia, and into femur. Principal group of fibers a long, tapering bundle (fig. 36 C, 110) arising proximally on posterior wall of femur and inserted on end of tendon ; two smaller groups of fibers in upper end of tibia, one arising anteriorly in base of tibia, the other dorsally, both inserted on tendon just above middle of tibia. Since the second thoracic spiracle lies within the region of the meso- thorax, its muscle belongs to the same segment. 111. Closing muscle of the second spiracle (fig. 52 B).—Origin on small lobe (0) of posterior dorsal margin of mesocoxal cavity ; inser- tion on ventral lobe of spiracular lips (7). THE METATHORACIC MUSCLES The musculature of the metathorax almost duplicates that of the mesothorax, with the principal difference that there are no oblique dorsal muscles and that there is only one pair of tergo-sternals in the metathorax. 112. Longitudinal dorsal muscles (fig. 34).—Most of the fibers extend between middle phragma and third phragma (3Ph), though a few dorsal ones are attached posteriorly on the postnotal plate (PNs). NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 67 113. Tergo-sternal muscle (fig. 34).—A large muscle, the first of the inner lateral series in metathorax, attached dorsally on lateral prescutal lobe, and below by a wide base on lateral part of sternum before coxal cavity. This muscle corresponds with 83 of the meso- thorax, a scuto-sternal muscle (84) being absent in the metathorax. 114. Pleuro-alar muscle: flexor of the hind wing (fig. 38, 114).— This muscle consists of two bundles of fibers in metathorax, one ex- ternal, the other internal, both arising from upper end of pleural ridge, and inserted on ventral surface of third axillary sclerite of wing base. The outer muscle is not visible from mesal plane until the first 1s removed. : 115. Pleuro-sternal muscle (figs. 34, 35).—A dense mass of very short fibers connecting pleural apophysis with apophysis of meta- sternum. 116. Fifth ventral longitudinal muscle (figs. 34, 35).—A strong fiber, apparently a sclerotized muscle, extending from posterior edge of mesosternal apophysis (SA) to median anterior angle of meta- sternal apophysis (SA;). 117. Sixth ventral longitudinal muscle (figs. 34, 35).—A slender muscle arising on second spina (2Spn), becoming tendinous pos- teriorly ; extends posteriorly and laterally to inner extremity of pleural apophysis of metathorax. The ventral longitudinal muscles of the metathorax have evidently lost their contractile nature because of the fusion of the mesosternum and metasternum, and are converted mostly into sclerotic strands to brace the pull of the mesothoracic ventral muscles (60, 87, 8S) on the sternal plates of the prothorax. The following thirteen muscles (118 to 130) are muscles of the metacoxa and the hind wing. 118. Tergal promotor of the coxa (figs. 34, 38 A).—Lies immedi- ately behind the tergo-sternal (fig. 34, 7273).’Arises dorsally on lateral area of scutum (fig. 38 A) ; inserted ventrally on apodemal disc of anterior angle of coxa (fig. 38 D, F, 178). 119. First tergal remotor of the coxa (figs. 34, 38 A).—A large muscle arising from posterior scutal margin; goes downward and posteriorly, behind pleural arm, to apodemal disc on posterior inner angle of coxa (fig. 38 D, F, 179). 120. Second tergal remotor of the coxa (figs. 34, 38 A).—A slender muscie lying close behind r79, tapering ventrally to slender apodeme arising from extreme posterior angle of coxa (fig. 38 B, D, F, 120). 68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 2Ba WPz Sa / / 1B Fic. 38—Muscles of the hind coxa and trochanter of Dissosteira. A, tergal muscles of leg base, and the tergo-sternal muscle (773), right side, inner view. B, sternal and coxal muscles of basalar and subalar sclerites (1Ba, 2Ba, Sa). C, abductor muscles of coxa. D, general view of muscle attachments on base of right coxa, inner view. E, sternal muscles of leg base, dorsal view. F, coxal muscle attachments, dorsal view. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS ° 69 The innermost series of lateral muscles includes two body branches of the trochanteral depressor (fig. 38 A, 733c) which will be described later. By removing the muscles attached on the tergum, there is ex- posed the outer series of pleural lateral muscles pertaining to the leg and wing, and the sternal muscles of the coxa. 121. Anterior rotator of the coxa (figs. 34, 35, 38 E).—A large muscle with fibers arising in two groups, one from lateral part of ster- num before base of sternal apophysis, the other from sternellar lobe behind the apophysis ; all fibers converge to insertions on anterior angle of coxa just mesad of stalked apodeme of 178 (fig. 38 D, F, r2r). 122, 123, 124. First, second, and third posterior rotators of the coxa (figs. 34, 35, 38 E).—Origins on posterior margin of lateral arm of metasternal apophysis ; insertions posteriorly on base of coxa, the first (fig. 38 D, E, F, 122) on process of meral region, the second (123) just within posterior angle of coxa, the third (124) on posterior part of meral rim of coxa. The innermost pleural muscles are the large basalar and subalar wing muscles (fig. 38 B, 127, 128, 129) ; external to them are the abductors of the coxa. 125. First abductor (accessory promotor) of the coxa (fig. 38 C).— A small muscle arising from anterior edge of metepisternum just behind and below second spiracle (2S/) ; insertion anteriorly on ex- ternal margin of coxa (fig. 38 C, D). Anatomically this muscle evi- dently belongs to the abductor system of the coxa, but apparently it functions as an accessory of the tergal promotor (D, 778). 126. Second abductor of the coxa (fig. 38 C).—A large flat muscle arising on inner face of episternum and on anterior surface of pleural ridge ; fibers converging to insertion on slender apodeme (fig. 38 D, F, 120) arising in articular membrane at base of coxa just before pleural articulation. 127. First pronator-extensor of the hind wing (fig. 38 B).—A large muscle attached dorsally on first basalar plate (7Ba), and ventrally on lateral part of sternum before coxa and laterad of base of the tergo- sternal muscle (figs. 34, 38 A, z73). 128. Second pronator-extensor of the hind wing (fig. 38 B).—Lies close behind 127; attached dorsally on second basalar plate (2Ba), ventrally on lateral rim of coxa (fig. 38, D, F, 128) anterior to pleural articulation (c). 129. Depressor-extensor of the hind wing (fig. 38 B).—A powerful muscle, attached dorsally on inner disc of subalar plate (Sa), and ventrally on wide basicostal surface of meral region of coxa (fig. 38 D, F, 129). 7O SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 130. Adductor of the coxa (fig. 38 C, D, E, F).—Origin on pos- terior surface of lateral arm of sternal apophysis (E) beneath base of first posterior rotator (122) ; goes posteriorly and downward be- low 123 and 124 to posterior part of inner margin of coxa (C, D, Je 82 10)) The following muscles belong to the telopodite of the hind leg. The total number is the same as in the fore and middle leg, but there are two distinct levators of the trochanter, and a reductor of the femur _is lacking. 131. Anterior levator of the trochanter (figs. 36 D, 39).—Origin on dorsal part of anterior wall of coxa; insertion on anterior lobe of dorsal rim of trochanter (fig. 36 D). 132. Posterior levator of the trochanter (figs. 36 D, 39). —A two- branched mus¢le arising dorsally in base of coxa ; both branches (132a, 132b) inserted on levator apodeme and supporting plate in dorsal articular membrane close to rim of trochanter (fig. 36 D). 133. Depressor of the trochanter (figs. 38 A, E, 39).—This muscle, as in the other legs, consists of five branches, two of which arise in the coxa, and three in the metathorax ; all are inserted on ventral rim of trochanter and together constitute a strong depressor of the telopo- dite. The coxal branches arise one anteriorly (fig. 39, 133a), the other posteriorly in ventral part of coxa. Two of the body branches arise on scutum of metatergum, one from lateral margin, the other (fig. 38 A, 133c) from center of lateral field. These two branches converge downward and unite before the pleural arm in a broad, tough band of fibers that curves posteriorly beneath the pleural arm (P/A) to enter the coxa. The third body branch arises from under surface of lateral arm of sternal apophysis (fig. 38 A, E, 133d). 134. Anterior levator of the tibia (figs. 36 F, 39)—This muscle appears to be represented in the hind leg of Dissosteira by only a very delicaté tendinous strand arising from the anterior angle of the tibial base (134Ap), and extending proximally for a short distance against the anterior wall of the distal part of the femur. The writer was un- able to discover muscle fibers attached to this tendon. 135. Posterior levator of the tibia (figs. 36 F, 39).—This great muscle occupies most of the cavity of the femur (fig. 39 A, B). The fibers arise in short, overlapping bundles from anterior and posterior walls of femur where they are attached on the spaces between the “fish-bone”’ ridges, with dorsal fibers of posterior set (17350) arising in dorsal crest of femur. Anterior and posterior fibers converge to sides of a large, thin, flat apodeme that tapers distally to a thick stalk NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 71 (fig. 39 A, 135AP) arising from dorsal margin of base of tibia. On the base of thrs apodeme are inserted two short, strap-like branches (fig. 36 F, 135c, 135d) arising dorsally in distal part of femur. 136. Depressor of the tibia (fig. 39).—A relatively small muscle with long, slender fibers (1736a) arising in ventral part of femur and converging to sides of long, tapering apodeme arising in ventral mem- brane of knee joint. The terminal, strap-like part of this apodeme slides over a strong, internal process (a) of ventral wall of femur. —— a v4 / Ny NS Il (Gye Aree Abie Fic. 39.—Musculature of the hind leg of Dissosteira. A, left leg, anterior (outer) view. B, cross-section through basal half of left femur, proximal end of distal piece, showing positions of levator and depressor muscles of tibia and of principal tracheae. Two small, anterior and posterior bands of fibers, arising on dorsal wall of femur, are inserted on apodeme near its base, the anterior one (136b) shown in the figure. 137. Levator of the tarsus (fig. 39)—A very small dorsal muscle in distal end of tibia, inserted on dorsal rim of base of tarsus. 138. Depressor of the tarsus (fig. 39).—A small muscle, but longer than the levator, arising ventrally in distal part of tibia, inserted on ventral lip of base of tarsus. 139. Depressor of the pretarsus: retractor of the claws (fig. 39).— Comprises three small groups of fibers, one arising posteriorly in ven- tral part of femur among fibers of tibial depressor, the second (139d) 72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 in proximal end of tibia, the third (z39c) on ventral wall of basal half of tibia; all inserted on fine, tendon-like apodeme (139 Ap) arising from unguitractor plate at base of claws. IV. THE LEGS AND THEIR MUSCLES The legs of the grasshopper are all of typical form and segmenta- tion, but the hind legs, being specially developed as organs of leaping, are not only of greater size than the others but differ from them in certain details of structure and in the relative proportions of some of the muscles. When the grasshopper sits in an ordinary resting posi- tion it supports itself principally on the first and second pairs of legs, the tibiae of the hind legs being flexed against the under surfaces of day, Ne De tn Gee, ir Fic. 40.—Middle leg of Dissosteira, anterior surface. Ar, arolium; Cx, coxa; Fm, femur; Tar, tarsus; Tb, tibia; Tn, trochantin; Tr, trochanter; Un, claw. the femora, with the knees usually held low and the tarsi barely touch- ing the ground. (The grasshopper of illustrations commonly rests on all three pairs of legs, with the hind knees elevated and the tibiae ex- tended.) In its natural resting attitude, the insect is always ready for a leap, the spring being caused by a forcible extension of the hind tibiae, probably accompanied by a strong depression of the trochantero- femoral parts of the legs. The chief function of the first and second legs is the support of the body and the directing of the few movements of walking or of changing the resting position ; the first legs are ac- tively used also during feeding for grasping and manipulating the edge of the leaf. When the grasshopper walks the hind legs are used with the others in the usual fashion. In describing the legs it is customary to use terms of orientation as they would apply if the appendage were extended laterally at right angles to the body. Preaxial and postaxial surfaces are called anterior and posterior, and upper and lower surfaces are dorsal and ventral. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 73 STRUCTURE OF THE LEGS The general form of a grasshoppper’s leg is shown in the illustra- tion of the middle leg of Dissosteira (fig. 40). The appendage con- sists of a cova (Cx), a trochanter (Tr), a femur (Fm), a tibia (Tb), a three-segmented tarsus (Tar), and a pretarsus comprising a pair of lateral claws (Un) and a median arolium (Ar). In the articular mem- brane before the base of each coxa there is a small trochantinal sclerite (Tn), best developed in the prothorax. Each leg is set into a membranous area, or coxal corium (fig. 26), occupying an oval'interruption in the sclerotic wall of the body between the pleuron and the sternum, known as the coxal cavity, the rim of which is reinforced by a submarginal inflection. The coxa is hinged to the body wall by only a single articulation, which is with the pleuron. The rudimentary trochantin (fig. 40, Tn) does not restrict the move- ment of the coxa. The anterior and middle coxae are free to move in any direction, but the hind coxae, which are directed posteriorly, have a more limited range of motion. The number of muscles inserted upon the hind coxae, however, suggests that what little movement these coxae possess is of much importance in the function of the hind legs. It should be noted that the articulating surfaces of the pleuro-coxal hinge are formed by inflections of the body and coxal walls, and there- fore lie on the inner surfaces of the latter (fig. 41 D). In this respect the basal joint of the leg differs from the basal articulations of the head appendages with the head wall, for the latter are external sur- faces of contact lying outside the articular membranes. The peculiar character of the pleuro-coxal (subcoxo-coxal) articulations attests, therefore, that these articulations are not homologous with the basal articulations of the gnathal appendages on the edge of the epicranium. The coxo-trochanteral joint and the articulations between the seg- ments of the telopodite, except the trochantero-femoral joint, which is but little movable, are all of the dicondylic hinge type with anterior and posterior articulating points on a horizontal axis transverse to the length of the leg segments. Movement at these joints is approximately in the same vertical plane. The trochanters are closely attached to the femora, but the hinge lines lie in a vertical plane, and the presence of a posterior femoral muscle in the trochanter of the first and the second leg (fig. 36 A, 72) shows that the primitive motions at the trochantero- femoral joint were movements of production and reduction. The seg- ments of the tarsus are movable on each other, but since they have no musculature, they can be moved only as they are influenced by the tendon of the ungual retractor which passes through them (fig. 44, ’). 74. SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 The coxae.—The three coxae of the grasshopper differ somewhat in their positions on the body. The first is the most freely movable; it projects downward and its base is almost horizontal. The second coxa is directed outward, downward, and posteriorly; its base lies in an oblique plane between the pleuron and the sternum. The hind coxa is directed posteriorly ; its basal aperture is on the inner face and lies in an approximately vertical, longitudinal plane. Fic. 41.—Structure of the coxae of Dissosteira. A, first coxa and base of telopodite, left, anterior surface. B, base of middle leg, left, anterior surface. C, hind coxa and trochanter, left, anterior (outer) surface. D, articulation of middle coxa to pleural process, right, inner view. 95Ap, apodeme of second abductor of middle coxa; Bc, basicosta of coxa; bcs, basicostal suture; c, pleural articulation of coxa; Cvs, hind coxa; cxs, coxal suture; Epm, epimeron; Eps, episternum; f, anterior coxo-trochanteral articu- lation; Mer, meron; PIS, pleural suture; 7, trochantin; 77, trochanter. Each coxa presents a well-marked basal rim, or basicoxite, set off by a submarginal basicostal suture (fig. 41 A, B, bes) which forms internally a strong basicosta (D, Bc). Laterally the costa of the mid- dle coxa (fig. 37 B) and of the hind coxa (fig. 38 D, F) are enlarged into wide, shelf-like plates for the accommodation of muscle attach- ments. The basicoxite is very narrow or obsolete on the mesal surface of the coxa, but on the lateral surface it forms a distinct prearticular and a postarticular lobe, the latter being known as the meron (fig. 41 B, Mer). The basicoxal lobes are well developed on the hind coxa (C) NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 75 but they are inconspicuous externally because each is bent outward and flattened upon the dorsal wall of the coxa. The articular surface (c) by which the coxa is hinged to the internal coxal process of the pleuron (D) is strongly inflected mesally in such a manner as to bring the point of suspension near the central axis of the coxa, thus giving the coxal muscles a leverage on all sides of it (fig. 43). Each coxa has a dicondylic hinge with the trochanter (fig. 36 D, f, g), the axis of which is horizontal and transverse to the length of the leg. The dorsal sur- tace of the coxa is deeply emarginate between the hinge points, and the ample articular membrane that occupies the notch allows a free upward movement of the telopodite. When the latter is deflexed, the ventral lip of the trochanter passes inside the lower edge of the coxa. The anterior wall of the prothoracic coxa is marked by a coxal suture (fig. 41 A, cvs) which extends from the anterior trochanteral articulation (f) to the basicostal suture at the articulation of the tro- chantin (Tn). The middle coxa (B) has a similar suture (cvs) ending at the trochanteral articulation (f), but it begins basally at the pleural articulation (c) and thus falls in line with the pleural suture (PIS) of the mesopleuron. The suture is absent in the hind coxa (C). The coxal suture, when present, forms a ridge on the inner surface of the coxal wall (fig. 36 A), the purpose of which is evidently to strengthen the latter. A coxal structure such as that of the middle leg of the grasshopper (fig. 41 B), in which the anterior wall is divided by a groove (cs) continuous with the pleural suture, is likely to be confused with the quite different structure illustrated by the coxa of Panorpa (fig. 14 A), in which the postarticular part of the basicostal suture (bcs) bends distally in the coxal wall and also falls in line with the pleural suture (PIS). The fundamental differences in the two cases, however, are quite apparent: in the grasshopper (fig. 41 B) the outer wall of the coxa itself is divided; in Panorpa (fig. 14 A) the meron (Mer) is greatly enlarged and is extended into the posterior coxal wall. The internal ridge of the coxal suture in the prothoracic and meso- thoracic legs of Dissosteira is continued through the anterior coxo- trochanteral articulation (fig. 36 A, f), giving a firm but flexible union between the two articulating segments. The posterior articulation be- tween the coxa and trochanter of the first and second legs consists of a condyle on the trochanter opposed by a concave surface on the coxa, but the two are united by membrane. In the hind leg both coxo- trochanteral articulations consist of opposing. processes united by ligament-like thickenings of the articular membrane (fig. 36 D, f, g). 76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The trochanters——The trochanteral segments of the prothoracic and mesothoracic legs have the usual form of the trochanter in insects, each being a short segment articulating as just noted with the coxa, and united distally with the femur. The trochantero-femoral union has an obliquely vertical hinge line and is perhaps slightly movable, since a femoral reductor muscle is present in each of the first and second legs (fig. 36 A, 72). The trochanter of the hind leg is a short ring-like segment (fig. 36 D, Tr) expanded on the posterior (mesal) surface, but so narrow externally as to be scarcely perceptible here (fig. 39, Tr) between the coxa and the base of the femur. It is immovably con- nected with the femur but not fused with it, and there is no trochantero- femoral muscle in the hind leg (fig. 39 A). The apodemes of the leva- tor and depressor muscles of the trochanter arise from small sclerites at the base of the trochanter in the dorsal and ventral articular mem- branes (fig. 36 D). The femora.—In the first and the middle leg the femur is a simple elongate segment (fig. 40, Fm) somewhat flattened in its antero- posterior diameter (fig. 36 C). At the distal end of the femur the anterior wall is expanded into a broad lobe that conceals the anterior femoro-tibial articulation (fig. 36 E, 1); the ventral wall is deeply emarginate and occupied by an ample articular membrane (fig. 36 B) which allows a free flexion of the tibia beneath the femur. The femur of the hind leg (fig. 39, Fm) contains the principal leap- ing muscles, which are the extensors of the tibiae (135) ; the hind femur is consequently greatly enlarged and is provided with special structural features. Its length is more than twice that of the middle femur, and its greatest vertical diameter is equal to the length of the prothoracic femur. The flat anterior and posterior surfaces (fig. 39 B) are ridged longitudinally above and below, and the space between is marked by the “fish-bone” pattern of a double series of oblique ridges. The latter separate the lines of attachment of the fiber bundles of the extensor muscles of the tibia on the inner walls of the femur (fig. 39, 135a). The distal end of the hind femur (fig. 36 F) is structurally similar to that of the first and second femora (E), but its anterior and posterior walls are strengthened by strongly sclerotized plates. The tibiae —The tibiae are of similar form and structure in all the legs, each being a slender shaft used as a lever rather than as a con- tainer for muscles, and so constructed that it can be folded beneath the femur. The femoro-tibial articulation is a strong dicondylic hinge (fig. 36 E, F, 1, m), and the dorsal lip of the tibial base projects well within the end of the femur to give an efficient leverage to the extensor NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 77 muscles (fig. 44). The ventral, flexor muscles are inserted upon an apodeme that arises from a small sclerite in the ventral membrane of the knee joint. The knee mechanism is most strongly developed in the hind leg (figs. 36 F, 39). The base of the tibia here forms a well dif- ferentiated articular head bent toward the femur almost at right angles Fic. 42.Tarsus and pretarsus of Dissosteira. A, tarsus of middle leg disjointed, showing levator and depressor muscles (108, 09) inserted on basal subsegment, and tendon-like apodeme (110A) of retractor of claws (Un) arising on unguitractor plate (Utr) and extending through tarsus. B, dorsal view of distal end of tarsus (Tar), arolium (Ar), and claws (Un), the latter articulated to unguifer (Uf) of tarsus. C, ventral view of pretarsus and end of tarsus, showing planta (Pin) and unguitractor plate (Utr) in base of pretarsus. to the length of the segment (fig. 39), and the dorsal lip of the tibial base is produced far into the end of the femur by an inflection of the articular membrane. The first and second tibiae are each provided with two rows of large, flexible, hollow spines on the distal half of the under surface, while the hind tibia has two rows of similar spines on its dorsal surface, but none on the ventral surface except at the end. The tarsi—tThe tarsi are each composed of three segment-like pieces (fig. 40, Tar) ; but the tarsal subdivisions, or articles, are clearly not 78 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 segments equivalent to the other parts of the leg, for they are inter- connected only by infolded membranes in which there are no sclerotic points of articulation, and none, except the basal one, is ever provided with muscles (fig. 42 A). The large basal subsegment of the grass- hopper’s tarsus bears three pairs of cushion-like pads on its under sur- face ; the middle subsegment has a single pair ; the longer terminal one has no pads. The presence of three pads on the basal subsegment 1s suggestive that this piece is a composite of three primary tarsal articles. The tarsal pads have been termed euplantulae by Crampton (1923). The pretarsi.—The terminal segment in each leg of the grasshopper bears a pair of large lateral claws (fig. 42 A, Un), but it is itself reduced to a simple median lobe, the arolium (B, C, Ar), and has two sclerites in its ventral wall (C, Pin, Uir). The proximal sclerite is the unguitractor plate (Utr) ; its base is invaginated into the end of the tarsus and gives attachment to the tendon-like apodeme (110A) of the depressor muscle of the pretarsus, known as the retractor of the claws. A levator of the pretarsus is lacking in all insects. The distal ventral sclerite, possibly a subdivision of the unguitractor, is distin- guished as the planta (Pin). The claws arise from the dorso-lateral parts of the base of the pretarsus and are articulated dorsally to the unguifer area on the end of the tarsus (fig. 42 B, Uf). MUSCLES OF THE LEGS The muscles of an insect’s leg are comprised in three groups: (1) muscles that move the limb as a whole; (2) muscles that move the telopodite ; (3) muscles that move the segments of the telopodite upon each other. The muscles of the first group have their origins entirely within the body ; they are inserted on the base of the coxa, on the tro- chantin, or on apodemes arising in thé coxal corium. The muscles of the telopodite arise in the coxa and within the body ; they are inserted on the trochanter or on apodemes arising close to the base of the tro- chanter in the articular membrane of the coxo-trochanteral joint. The muscles of the individual segments of the telopodite beyond the tro- chanter arise in the segments proximal to their insertions; they are inserted either on the bases of the segments they move or on apodemes arising in the articular membranes. Muscles of the leg base-——The muscles associated with the coxa that move the leg as a whole fall into three groups according to their points of origin ; namely, muscles that arise on the tergum, muscles that arise on the sternum, and muscles that arise on the pleuron. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 79 The basal leg muscles arising on the tergum comprise anterior and posterior groups of fibers, or tergal promotors (fig. 43 A, I) and tergal remotors (J). The tergal promotors are usually contained in a single muscle, which is inserted on the trochantin (B, 77) when this sclerite is present and well developed, otherwise in the articular mem- brane or on the base of the coxa. The tergal remotors often form a Pay 2% Fic. 43.—Diagrams of the cardinal axes of motion in a coxa articulated to the body by a pleural articulation only, and the coxal musculature in a wing-bearing segment. A, mechanism of the coxal movements on the pleural articulation (c), inner view. The cardinal movements are: (1) promotion and remotion on a trans- verse axis (c c) by tergal promotor and remotor muscles (J, J); (2) rotation on a vertical axis (d d) by anterior and posterior sternal rotator muscles (K, L); and abduction and adduction on a longitudinal axis (b b) by a pleural abductor muscle (J/), and a sternal adductor muscle (N) arising on sternal apophysis. B, diagram of typical musculature of a coxa in a wing-bearing segment freely movable on the pleural articulation. /, promotor of coxa, tergum to trochantin; J, remotor, tergum to coxa; K, anterior rotator, sternum to coxa; L, posterior rotator, sternum or spinasternum to coxa; M, abductor, episternum to coxa; M’', basalar muscle, basalare to coxa; M”, subalar muscle, subalare to coxa (M' and M” are pleural abductors of coxa in the nymph, fig. 27 C) ; N, adductor, sternal apophysis to coxa. group of muscles. In Dissosteira the tergal promotor is a single muscle for each leg: that of the prothorax (fig. 33 A, 62) is inserted on the trochantin (Tm) ; that of the middle leg is inserted by an apodeme (fig. 37 A, B, C, &9) arising between the trochanter and the coxa; whereas that of the hind leg (fig. 38 A, 778) is attached directly on the anterior angle of the coxa (A, D, F, 178). The tergal remotors of the first leg comprise a group of three muscles (fig. 33 A, B, C, D, 63, 64, 65) inserted on the posterior angle of the coxa; those of the middle leg include two muscles inserted by apodemes on the posterior angle of the coxa (fig. 37 A, B, 90, 91) ; and those of the hind leg em- 80 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 brace two muscles (fig. 38 A, 179, 120) similarly inserted (D, F). The two sets of tergal muscles, promotors and remotors, are clearly antagonists pulling on opposite extremities of the longitudinal basal axis of the coxa (fig. 43 A, b-b), the fulcrum of which is at the pleural articulation (c). The sternal musculature of the coxa, when complete, includes three groups of fibers, one inserted on the anterior angle of the coxal base, one on the posterior angle, and one on the mesal rim. The first two are the anterior and posterior rotators (fig. 43 B, K, L) serving to turn the coxa in the plane of its base (A) on the pleural articulation (c). In the foreleg of Dissosteira an anterior rotator is lacking, but there are two posterior rotators (fig. 33 C, 66, 67), the first arising on the base of the sternal apophysis (SA), the other on the spina (1Spn) ; both are inserted on the posterior angle of the coxa (C, D). The middle leg has a single anterior rotator (fig. 37 A, B, 92) and a single posterior rotator (93), the first arising on the sternellar lobe of the mesosternum (fig. 35, 92), the second (93) on the spina (2Spu). In the hind leg there is a single, large two-branched anterior rotator of the coxa arising on the metasternum laterad of the base of the sternal apophysis (fig. 35, 721), and inserted on the anterior angle of the coxa (fig. 38 D, 121) ; and there are three posterior rotators (figs. 35, 38 E, 122, 123, 124) all arising from the arm of the sternal apophysis. The mesal sternal muscle of the coxa (fig. 43 B, NV) is the adductor. It pulls upward (A, NV) on the inner end of the transverse axis (c-c) of the coxal base passing through the pleural articulation (c). In each segment of Dissosteira the coxal adductor arises on the under surface of the arm of the sternal apophysis (figs. 33 C, 69; 37 A, 100, IOI; 28:6, Di. Hoel 20). The pleural muscles of the coxa include the functional abductor fibers (fig. 43 B, 1) which directly oppose the adductor (NV), and, in the wing-bearing segments, two other muscles (B, ’, M”) that ap- pear to be derived from the primitive abductor system. In the foreleg of Dissostcira the abductor of the coxa is a two- branched muscle (fig. 33 D, 68a, 68b) arising on the inner surface of the invaginated episternum (Eps). In the middle leg the abductor group comprises three distinct muscles (fig. 37 A, 94, 95, 96) all arising on the episternum. The first two are inserted by flat apodemes anteriorly on the outer rim of the coxa (B, C, 94, 95) and perhaps function here as accessory promotors. The large third muscle (A, 96), however, is inserted close before and distinctly laterad of the pleural articulation (B, c) by a slender apodeme (96) arising in the coxal corium, and it must be the functional abductor of the coxa. In NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 81 the hind leg there are two muscles in the abductor group (fig. 38 C, 125, 126), one being a small anterior muscle (725), apparently acces- sory to the promotor (A, 178), the other a large posterior muscle (C, 726) which unquestionably functions as an abductor. The pleural muscles associated with the functional abductor mus- cles of the coxa in the wing-bearing segments are attached on the outer rim of the coxa (fig. 43 B, M’, M@”) and, in adult insects, arise typi- cally on the epipleural basalar and subalar sclerites (figs. 37 A, 98, 99; 38 B, 128, 129), and function as wing muscles. In some adult insects, as in Panorpa (fig. 14 B), the first of these muscles (M’) arises on a dorsal lobe of the episternum (Ba), which is clearly the homologue of the basalar plate or plates in other insects, such as are present in the adult of Dissosteira (fig. 26, Ba). The posterior epipleural muscle (M”) is always attached to the subalar sclerite in adult insects (figs. 14 B, 37 A, 38 B, Sa). Both muscles, however, in the nymph of Dissosteira (fig. 27 C, M’, M”) and in other nymphal Orthoptera, arise directly from the upper edge of the pleuron, one on the epis- ternum, the other on the epimeron, and, if they act together, they must be abductors of the coxa. The epipleural muscles, therefore, appear to be groups of coxal abductor fibers that have become specially developed as secondary wing muscles in the adult. The first is a pronator-extensor of the wing; the second is the depressor-extensor of the wing (fig. 49, M7’, M”). The foregoing analysis of the basal leg musculature of Dissosteira shows that the coxa is provided with six sets of muscles, including an anterior and a posterior group of fibers arising on the tergum (fig. 43 B, I, J), an anterior and a posterior group arising on the sternum (K, L), a lateral group arising on the pleuron (M, and also M’' and M” in the wing-bearing segments), and a mesal group arising on the sternum (NV). The anterior and posterior dorsal and ventral muscles may be supposed to represent the theoretical primary tergal and sternal promotors and remotors of a primitive limb basis (fig. 6, I, J, K, L), which have become transferred to the coxal region (fig. 11) after the subdivision of the basis into subcoxa and coxa. The lateral and mesal muscles, therefore, are subcoxo-coxal muscles, the fibers of the first (JZ) retaining their origins on the subcoxal pleuron, those of the second (N) having been transferred to the sternum, perhaps by the incorporation of the ventral rim of the subcoxa into the definitive sternal plate. Muscles that move the telopodite—The muscles that operate the telopodite, or that part of the leg beyond the coxo-trochanteral hinge, 6 82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 comprise the muscles normal to the trochanter, which are a levator and a depressor arising in the coxa (fig. 44, O, Q), and also special depressor muscles (P) that have their origin in various parts of the body segment carrying the leg. The basal lip of the trochanter usually projects into the coxa well beyond the line of the coxo-trochanteral hinge, thereby giving a strong leverage to the depressor muscles in- serted upon it. The branches of the trochanteral depressor arising within the body segment vary much in different insects and in different segments of Fic. 44.—Diagram of the mechanism of the hind leg of a grasshopper. O, levator muscle of trochanter, or extensor of telopodite, origin in coxa; P, body branch of depressor of trochanter, or flexor of telopodite, origin on tergum; QO, coxal branch of depressor of trochanter; S, levator of tibia; 7, de- pressor of tibia; U, levator of tarsus; , depressor of tarsus; X, X, tibial branches of retractor of claws; x, tendinous apodeme of retractor of claws aris- ing on base of unguitractor plate. the same insect. In the prothorax of Dissosteira there are three body branches of the trochanteral depressor, one arising on the episternum (fig. 33 B, 77), the second on the pleural arm (C, 7Zc), and the third on the tergum (B, 71d). In the mesothorax there are two body branches of the muscle, both arising on the tergum. In the metathorax a long outer branch and an inner branch (fig. 38 A, 133c) arise on the tergum, and a short branch takes its origin on the under surface of the lateral arm of the metasternal apophysis (fig. 38 A, E, 133d). These muscles ordinarily serve to lift the body on the legs, but those of the hind legs of the grasshopper are probably accessory to the extensor muscles of the tibiae in the act of leaping (fig. 44, P). Muscles of the telopodite segments.—Since the trochantero-femoral joint usually has but little movement in insects, the muscles of the NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 83 femur arising in the trochanter are small or absent. In Dissosteira a posterior, or reductor, muscle only is present in the trochanter of the first leg (fig. 36 A, 72) and in that of the second leg. In the hind leg there is no movement at the trochantero-femoral joint and femoral muscles are lacking. The usual flexion between the trochanter and the femur of insects is anterior and posterior (production and re- duction), and generally only a reductor muscle is present, called the “rotator” of the femur by some writers (Morison, 1927; Weber, 1929). The femur is occupied mostly by the tibial muscles (fig. 44, S, T), but it contains also the most proximal branch of the flexor of the claws (X). The tibial musculature comprises levator muscles (S) and depressor muscles (7). In Dissosteira there are two levator muscles in each leg, a larger posterior one (fig. 36 E, 106, F, 135), and a very small anterior one (EF, 105, F, 134). In the fore and middle legs the depressor of the tibia (fig. 36 B, C, 107) is larger than the levator, and it has a basal branch arising in the trochanter (B). In the hind leg the relative proportions of the two muscles are reversed, the posterior levator, or extensor, of the tibia consisting of the great masses of fibers arising on the ridged anterior and posterior walls of the femur (fig. 39, 735a, 1350), and including smaller branches (135c) arising on the dorsal wall in the distal part of the femur. The anterior levator of the tibia in each leg consists of a very slender bundle of fibers arising anteriorly in the base of the femur (fig. 36 A, 73) and inserted by a long, thread-like apodeme on the head of the tibia (FE, r0o5Ap, F, 134Ap). The tibiae contain the levator and depressor muscles of the tarsus, and the tibial branches of the flexor of the claws. The tarsal muscles are relatively largest in the fore and middle legs of Dissosteira; in the hind leg they occupy only the distal part of the tibia (fig. 39, 137, 138). The tarsus contains no muscles, the tarsal segments, as before noted, being flexible upon one another but not independently movable. This condition pertains to all insects. The tarsus is traversed by the “tendon,” or thread-like apodeme, of the flexor of the claws (figs. 39, 139AP, 44, x). The claws of insects are provided with only a flexor, or rectractor, muscle, which is the depressor of the pretarsus (fig. 44 X), or the homologue of the depressor of the dactylopodite in arthropods gen- erally. The fibers of the claw muscle arise in several groups in the tibia and femur, and are inserted on a long tendon-like apodeme that arises from the base of the unguitractor plate (fig. 42 C, Utr) and 84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 extends through the tarsus and tibia into the femur. In Dissostetra two small groups of fibers of the claw muscle arise in the upper part of the tibia (fig. 39, 139, 139c), and one arises posteriorly in the base of the femur (fig. 36 A, 78). The pull of the muscles on the tendon retracts the unguitractor plate and flexes the claws ventrally. The extension of the claws probably results from the elasticity of their basal connections and the pressure on the supporting surface. Typically, the muscles of the pretarsus should arise in the tarsus. It is probable, therefore, that the extension of the fibers into the tibia and femur in insects (and also in chilopods and diplopods) is a sec- ondary condition produced by a proximal migration of the primitive muscle. In Crustacea and Arachnida the pretarsus, or dactylopodite, is provided with levator and depressor muscles, both of which have their origin in the tarsus, or propodite. In some Arachnida there are two pretarsal claws, as in most insects, but the pretarsus has lateral articulations with the end of the tarsus, and is provided with dorsal and ventral muscles. V. THE WINGS AND THEIR MECHANISM The wing mechanism of the grasshopper is equally developed in each segment of the pterothorax. The hind wings, though much more extensive than the forewings, or tegmina, and probably the chief organs of flight, have no advantage over the latter except in the stronger development of the flexor apparatus. The forewings, on the other hand, have a more powerful levator equipment than the hind wings because of the presence in the mesothorax of the second pair of tergo-sternal muscles attached dorsally on the scutum (fig. 34, 84). In structure, the hind wings (fig. 45 B) differ from the forewings (A) only in the reduction of the costal area and in the great ex- pansion of the anal area. STRUCTURE OF THE WINGS In general structure, articulation, and mechanism the acridid wings differ little from the wings of other Orthoptera. The tegmina when at rest are flexed over the body in a manner to form a high roof with steeply sloping sides (fig. 50 A, W.) covering the back of the abdomen and inclosing the folded hind wings (W,) in the space above the latter. The anal areas of the tegmina overlap dorsally in a median horizontal plane, the left tegmen being usually on top; the pre-anal areas form the lateral inclines of the tegminal roof. The bend be- NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 85 tween the two wing areas takes place along the anal fold (figs. 45 A, 50 A, AF), and is produced mechanically during the flexion of the wing. The broad hind wings are folded in a complicated manner, to eroc kM i Pra Mar “ \\ Hi Ju (RN \ 2G.) SASvIiCu WN yan i \ SS \ _ ;——1 SS ———— Oe — —— — 7A. B Fic. 45.—The wings and wing veins of Dissosteira. A, fore wing, or tegmen. B, hind wing. A, anal veins, anal area of wing ; 1A, first primary anal vein; 74, seventh primary anal; C, costa; 1Cu, first cubitus ; 2Cu, second cubitus; /, intercalary vein; 71, 7, secondary anal veins of first anal plait; k, first concave anal vein; Ju, jugal area of wing; /, second con- cave anal vein; M, media; Pra, preanal area of wing; q, basal support of anal veins; R, radius; A, first branch of radius; Rs, radial sector; r, first anal plait of wing; R-+ M, united shafts of radius and media; Sc, subcosta; VD, vena dividens. be described later, and when fully flexed are concealed beneath the overlying tegmina (fig. 50 A). The area of an insect’s wing presents usually three well-defined regions, namely, a preanal region, an anal region, and a small, pos- 86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 terior, basal region, generally membranous, which Martynov (1925) terms the jugal region. The three wing regions are shown in typical form in the forewing of the grasshopper (fig. 45 A). The preanal region (Pra) is that lying anterior to the anal fold; the anal region is the region of the anal veins (4), the jugal region (Ju) is the membranous basal fold of the wing. In many insects the jugal region contains one or two definite veins unconnected basally, or an irregular network of small veins. The hind wing of the grasshopper (fig. 45 B), and of other insects with similar fan-shaped wings, is usually regarded as differing from the forewing in the great expansion of the anal region. According to Martynov (1925), however, the true anal region of the hind wing in Acridium is that part (fig. 45 B, 7) between the anal fold, or vena dividens (VD), and the first vein springing directly from the basal support (q) of the anal fan (designated 1A in fig. 45 B). Three veins (1, 7, k), branching from a common base, lie in this region in the wing of Dissosteira. The following part of the wing, or that containing the veins attached directly to the basal support (q) of the anal fan, Martynov claims is a development of the jugal region of the more primitive type of wing. A jugal area thus developed into a functional wing region he calls the “ neala.” Martynov deduces his interpretations of the morphology of the acridid wing from a general study of the wings in other orders of insects. In Dissosteira, however, the vein designated 1A in the hind wing (fig. 45 B) is so clearly the homologue of 1A in the forewing (A), considering the basal relations and the connection with the third axillary sclerite (fig. 47 A, B, 3A), that Martynov’s interpretation is not convincing. The area (7) of the hind wing (fig. 45 B), lying between VD and 1A, forms the first fold of the anal region (fig. 50 B) in which the vein k occupies the position of a “ concave” vein at the bottom of the fold, while the two preceding veins (7, 7) strengthen the anterior wall of the fold. The three veins of this region (fig. 45 B, i, j, k) are branches of the first primary anal vein (14). Mar- tynov’s general study of the wing regions, however, throws much light on the wing mechanism and morphology. Venation of the wings—While the venation of the grasshopper’s wings is comparatively simple, it is difficult to make a satisfactory interpretation of the homologies of the veins in the posterior parts of the preanal regions. If the relation of the vein bases to the axillary sclerites is taken as a guide to the identities of the veins themselves, the veins of the adult may be named consistently in the two wings, but their relation to the nymphal wing tracheae is not clear in all cases. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 87 The forewing (fig. 45 A) has a broad anterior, or costal, area in which there is no vein represented by a costal trachea in the nymph (fig. 46 A), though the anterior margin is strengthened by a vein-like thickening. The first vein (fig. 45 A, C) is evidently the costa branch- ing from the subcosta (Sc), though the common basal stalk has the usual relation of the subcosta to the first axillary sclerite (fig. 47 A, 1Ax). The next vein (J) is unquestionably the radius, as shown by its distal branches and by its basal connection with the second axillary (fig. 47 A, 2Ax). The media (M) is united proximally with the radius and with one of the median sclerites of the wing base (m’). The first long vein following the media is a two-branched cubitus (1Cu), between which and the basal part of the media is the inter- calary vein (J). Then comes an unbranched vein, here designated 2Cu, lying close before the anal fold (AF), and finally a group of three veins (4) connected basally with the third axillary, or flexor sclerite of the wing base (fig. 47 A, 34x). If we identify the “anal veins” as those veins lying posterior to the anal fold and connected basally with the third axillary, there are then but three anal veins in the forewing of Dissosteira (fig. 45 A, A, fig. 47 A, 1A, 2A, 3A). An incomplete vein (fig. 47 A, s) lying just behind the anal fold (AF) is apparently a secondary vein. The vein immediately before the anal fold (2C) is the “ first anal ”’ of the Comstock-Needham system, but probably it is the vein regarded as a part of the cubitus by Tillyard (1919) and others, designated Cuz by Tillyard and cubital sector by Karny. In Dissosteira the vein in ques- tion has no basal connections and is here termed the second cubitus (2Cu). It clearly belongs to the cubital area of the wing. In the nym- phal wing of an acridid, as illustrated by Comstock and Needham (fig. 46 A), tracheal precursors of the cubitals are not evident, since the final group of three tracheae springing from a common basal stem would appear to represent the group of three anals in the adult wing (fig. 45 A, A). According to Comstock (1918), however, the first vein of this group is the “cubitus” (fig. 46 A, Cu), and the second the “first anal” (14). The identity between the nymphal tracheae and the adult veins in the forewing is certainly not clear, and no solution of the problem can be offered here. The vein tentatively called “second cubitus”’ in this paper (figs. 45 A, 47 A, 2Cu) is, by nomenclatural priority, the true anal vein, and the name “anal,” though a poor designation, should be retained for it, while a new term should be devised for the veins lying posterior to the anal plica associated with the third axillary sclerite. The fan- , 88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 like wing region between the anal and jugal plicae might appropriately be called the vannus (Latin, fan), and its veins termed the vannal veins. This region plays a passive part in flight. The pre-vannal part of the wing is the true remigium (Latin, oar) of the flight mech- anism, being the region of the wing directly productive of motion. We might then say that the area of the wing distal to the basal axillary region is divided into a remigial, a vannal, and a jugal region. The separating folds, when present, would then become the vannal and the jugal plicae. The jugal region expanded is the neala of Martynov. Fic. 46.—Wings of an acridid nymph. (From Comstock, after Comstock and Needham.) A, fore wing. B, hind wing. The tracheal identifications as given by Com- stock and Needham: 14, first anal; Cu, cubitus; MM, media; FR, radius; Sc, subcosta. In the hind wing (fig. 45 B) the costa (C) forms the anterior margin of the wing and is united basally with the subcosta (Sc). The base of the subcosta (fig. 47 B, Sc) does not reach the first axillary sclerite (14), evidently by reason of the reduction of the anterior process of the latter, neither does it articulate with the pre- scutal lobe of the tergum (fig. 22 A, 7), but it is connected with the latter by a ligament-like thickening of the wing membrane (fig. 47 B, d). The radius (R) is well developed, branched distally, and con- nected basally with the second axillary (fig. 47 B, 247). The ap- parent media is united proximally with the radius; its free part con- NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 89 sists of a single branch (J) given off from the radial sector (Rs). Between the basal radio-medial shaft (A + MM) and the first anal fold, there are two veins in the cubital area (1Cu, 2Cu) ; the first (fig. 47 B, rCw) is united proximally with the radio-media, the second (2Cw) has no basal connections. In the hind wing, therefore, as in the forewing, there are two distinct cubitals, here named the first cubitus (zCu) and the second cubitus (2Cu). Each of these veins is represented by a trachea in the hind wing of the nymph (fig. 46 B) ; the first is the “cubitus” (Cw) of Comstock, and the second the “first anal”? (14). Since both of these veins lie anterior to the anal fold in the adult wing (figs. 45 B, 47 B), however, the writer would agree with Tillyard (1919) that the second is a cubital rather than an anal vein. The orthopteran wing suggests that the second cubitus has the status of an independent vein rather than that of a basal branch of the first cubitus. The anal fold of the hind wing is double (fig. 50 B), consisting of two plicae, or lines of flection in the wing membrane, between which lies the vena dividens (figs. 45 B, 47 B, 50 B, VD). According to Till- yard the vena dividens is the “ first anal,” but since it has no basal con- nection with the other anals (fig. 47 B), the writer would regard it as a secondary, interpolated vein. The incomplete vein of the fore- wing lying just behind the anal fold (fig. 47 A, s) may represent the vena dividens of the hind wing, but it appears rather to correspond with the vein 7 of the hind wing (figs. 45 B, 47 B). The anal veins of the hind wing form a distinct group lying pos- terior to the anal fold. All the primary anals spring from a basal sup- port (fig. 47B, q) which is attached anteriorly to the distal arm of the third axillary (34%), and which, in the grasshopper, is braced posteriorly by an arm from the tergum (figs. 24, 47 B, p). There are ten primary anal veins. A fork from the first (714) divides into three branches (7, j, k) lying in the first lap of the wing that folds beneath the preanal region when the wing is flexed (fig. 50 B). Al- ternating with the primary, or “ convex,” anal veins are nine secon- dary “concave” veins lying in the troughs of the folds between the primary anals, while the vein (#) branching from the first anal is the concave vein of the fold between the vena dividens and the first anal (fig. 50 B, Rk). Articulation of the wings—In the membrane of each wing base are four axillary sclerites. The first and the fourth (fig. 47 A, B, 1Ax, 4Ax) are hinge plates articulating with the edge of the tergum; the second (24x) is the pivotal sclerite of the wing base ; the third (347) TH 7A Fic. 47.—The wing bases of Dissosteira. A, base of tegmen. B, base of hind wing. 14, 2A, 3A, 7A, first, second, third, and seventh primary anal veins; AF, anal fold; 1Ax, 2Ax, 3Ax, 4Ax, first, second, third, and fourth axillary sclerites ; C, costa; Cu, first cubitus; 2Cu, second cubitus; d, attachment of base of subcosta to prescutal lobe of tergum; I, intercalary vein; i, secondary vein of first anal plait; k, first concave anal vein; J, second concave anal vein; M/, media; m, m’, median plates of wing base; p, posterior arm of tergum supporting the anal veins; g, basal support of anal veins; R, radius; R + M, united basal shafts of radius and media; s, secondary vein of fore wing behind anal fold; Sc, subcosta; tg, tegular rudiment; ’D, vena dividens. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS gli is the flexor sclerite. In addition to the axillaries there are two plates in the median area of the forewing (A, m, m’), and a single median plate in the hind wing (B, m). The first axillary intermediates between the edge of the tergum and the second axillary, with each of which it is movably connected, and usually, by an anterior process, it articulates with the base of the subcostal vein. The first axillary is confined to the dorsal membrane of the wing base. In the forewing of Dissosteira the first axillary (fig. 47 A, rAx) is a flat plate with a narrow anterior process curved outward to meet the base of the subcosta. The sclerite bridges the lateral emargination of the tergum (fig. 22 A, Em) ; its anterior end is supported on the anterior notal wing process (ANP), and its pos- terior part is hinged to the lobe of the scutum (0) behind the emargi- nation ; its oblique outer margin articulates with the second axillary (fig. 47 A). The first axillary of the hind wing of Dissosteira (B, 1Ax) is exceptional in the reduction of its anterior process which does not meet the base of the subcosta (Sc). The second axillary presents an exposed surface in both the dorsal and the ventral membranes of the wing base. Its dorsal part forms a triangular plate (fig. 47 A, B, 2A) lying lateral of the first axillary, and closely hinged to the oblique outer margin of the latter; its pos- terior outer margin articulates with the proximal median sclerite (#7) ; to its anterior end is attached the base of the radius (/¢). The ventral part of the second axillary forms a strong, concave plate (fig. 48, 2Ax) resting by its lower edge on the pleural wing process (WP). The second axillary differs somewhat in shape in the two wings of Dissosteira, as shown in the figures, but its structure and associations are the same in both. The third axillary is developed principally in the dorsal wing mem- brane (fig. 47 A, B, 34%), but it includes also a small sclerotization in the ventral membrane (fig. 48, 341). The dorsal part of the third axillary (fig. 47) has the form of a strong bar extending outward, in the fully-expanded wing, from the small fourth axillary (44x) to the anal veins, which latter it supports by an arm bent forward from its distal end. The mesal part of the sclerite bears a strong, elevated process on its anterior margin upon which is inserted the flexor muscle of the wing. Distal to the muscle process, the proximal median plate (m) is firmly attached to the third axillary and is functionally a part of it. In the forewing (fig. 47 A) the distal median plate (m’) is hinged to the outer margin of the proximal plate. g2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 The fourth axillary (fig. 47 A, B, 44x) is a plate of the dorsal wing membrane only. It is small in each wing and serves merely as a connective between the edge of the tergum and the third axillary. It is probably a detached lobe of the tergum, since it is usually absent in insects that have a posterior notal wing process. Beneath the base of each wing are the epipleurites, or small scler- ites derived from the pleuron, which are intimately associated with the wing mechanism in the adult insect. In Dissosteira there are in each segment two episternal epipleurites, or basalares, (fig. 48, IBds, 2Baz, 1Baz, 2Ba;), and a single epimeral epipleurite, or subalare (Sa). The basalares are hinged to the upper edge of the episternum (Eps), and are connected with the subcostal region of the wing base by a ligamentous thickening (a) of the ventral wing membrane. The subalare (Sa) lies free in the subalar membrane behind the wing process, but it is connected with the ventral plate of the second ax- illary (2Ax) by a thickening (b) of the intervening membrane. THE WING MECHANISM Flying insects are unquestionably descended from wingless an- cestors. When paranotal lobes were first evolved on the thoracic seg- ments, the insect was already organized for terrestial locomotion— there was no provision for future organs of flight. When movable wings were evolved from the paranotal lobes, they had available for their purposes only a motor mechanism developed for other pur- poses. It needed but an area of flexibility at the base of each paranotal extension to convert the lobe into a movable flap. The dorsal ends of the pleura, previously supporting the bases of the paranotal lobes, easily became fulcra on which the wing flaps could rock up and down. A contraction of the longitudinal muscles of the dorsum could now give a down-stroke to the wing flaps by producing an upward curva- ture in the tergal plates of the wing-bearing segments, and probably at first the elasticity of the terga sufficed to produce the up-stroke. Thus, apparently, by the simple device of becoming flexible at their bases, the paranotal lobes became wings that could be weakly flapped up and down by the simple motor equipment already at hand. Modern insects, however, have added much to the primitive wing mechanism. In each of the wing-bearing segments there are powerful tergal-depressor muscles, which, since they do not occur in the pro- thorax or in the segments of the abdomen, are probably specially developed wing muscles, though they may be supposed to have been evolved from small, lateral tergo-sternal muscles such as are usually NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 93 present in the abdomen. Being attached ventrally on the sternum, these muscles indirectly impart a strong up-stroke to the wings by flattening the dorsal curvature of the tergum. The down-stroke of the wings produced by the contraction of the longitudinal dorsal muscles has been strengthened in two principal ways: first, by the obliteration of the secondary intersegmental membranes between the terga, thus eliminating lost motion ; and second, by the great enlarge- ment of the dorsal muscles themselves in the wing-bearing segments. hea a WP, _ 2 Nap bane a ~ _1Baz --2Baz Bal fos 2Bay Eps, \ Epm,\ Epsz \Epm; paaey Fic. 48.—Ventral surface of the base of the left tegmen, and upper part the pleuron of Dissosteira. a, thickening of membrane uniting basalar sclerites with humeral angle of wing ; 2A x, ventral plate of second axillary; 34x, ventral plate of third axillary ; b, connection between subalar sclerite and ventral plate of third axillary; 1Ba, first basalare; 2Ba, second basalare; Sc, base of subcostal vein; Sa, subalare; WP, pleural wing process. The suppression of the intertergal membranes has been accomplished by a fusion between the successive tergal plates, or by a forward extension of the precostal lip of the tergum until it meets the pos- terior edge of the preceding tergum. Thus are produced the post- notal plates between the mesothoracic and metathoracic terga, and between the metathoracic and first abdominal terga. The enlargement of the dorsal muscles has been accompanied by the development of supporting plates (phragmata) from the ridges of the muscle attach- ments on the primary intersegmental folds. Furthermore, each tergal plate has been strengthened and better adapted to its function in the flight mechanism by the development of internal ridges, the principal 94 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 ones of which are so arranged as to bring the peak of the curvature in the tergum on a transverse line between the wing bases. The Odonata are commonly said to have a wing mechanism quite different from that of other insects. On the basis of von Lendenfeld’s (1881) description of the odonate wing muscles, the dragonflies have been supposed to be equipped with a special set of muscles inserted directly on the wing bases. A study of the thoracic musculature in either the Anisoptera or the Zygoptera, however, will show that there are ony two small muscles that can be regarded as special wing muscles ; one of these is accessory to the pronator of the wing, the other to the depressor. The large pronator and depressor muscles, though they arise ventrally on the lower edge of the pleuron and are inserted directly on the two basal plates of the wing, are evidently the homologues of the basalar and subalar muscles of other insects. Two smaller muscles lying mesad of the pronator are clearly leg muscles since they have their origins on the coxa and their insertions on the extreme lateral edge of the tergum. Von Lendenfeld ascribed these muscles to the wings ; he describes them as arising on the pleuron and as inserted on the wings. Each wing has a homologue of the flexor muscle in other insects, though it does not function as such because of the lack of a flexor mechanism in the base of the odonate wing. The tergo-sternal muscles are highly developed, their ventral attach- ments are on the sternum and their dorsal attachments on the antero- lateral lobes of the tergum. The dorsal longitudinal muscles are re- duced to a pair of small, divergent fiber bundles attached anteriorly on the median apodemal spine of the tergum, and posteriorly on the anterior margin of the following tergum. The wing mechanism of the dragonflies is thus merely an extreme modification of that common to all insects. A wing, in order to be an efficient organ of progressive flight, must be capable not only of an up-and-down movement, but also of anterior and posterior movements accompanied by a partial rotation on its long axis. The anterior margin of the wing must be brought forward and deflected during the down-stroke, and lifted with a posterior movement during the up-stroke. The rotary movement of the insect’s wing is caused partly by the structure of the wing itself and its re- sponse to air pressure, and partly by the nature of the wing articula- tion on the body, but it is greatly augmented by muscles that pull downward on the base of the wing, one before the pleural fulcrum, the other behind it. These muscles are inserted on the basalar and subalar sclerites beneath the wing base (fig. 48, Ba, Sa). Two of them NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 95 are evidently muscles of the leg that have been taken over into the service of the wing, for they are attached ventrally on the coxa (fig. 49, M’, M”) ; the other (£) arises on the sternum, or in some insects on the pleuron, and is perhaps a specially developed wing muscle. The two muscles of the basalar sclerites (E, M’) are called pronators be- cause they deflect the costal wing margin. The muscle of the subalar sclerite (M”) not only deflects the posterior part of the wing, but it acts as a powerful depressor of the entire wing by reason of its con- nection (b) with the ventral plate (c) of the second axillary (24+). These muscles probably also enable the insect to alter its course during flight, and, by changing the plane of the wing movements, to hover in the air, or to fly sidewise or backward. Finally, most insects have found it advantageous to fold the wings posteriorly over the body. The folding of the wings has involved the development of a mechanism for their flexion and extension. The ability of the wing to be flexed depends upon the mechanism of its axillary region, but the flexing is caused by one or more flexor muscles arising on the pleuron and inserted on the third axillary sclerite (fig. 49, D). The extension of the wing is produced by the basalar and subalar muscles (F, M’, M”). Considering the other functions of these muscles, the first, therefore, is a pronator-extensor of the wing, the second a depressor-extensor. The special features in the mesothorax and the metathorax of the grasshopper that contribute to the mechanism of the wings have been described in Section II of this paper. It was there shown that the fusion of the pleurites and sterna of the mesothorax and metathorax converts these segments into a strong trough-like structure covered dorsally by the two wing-bearing terga. The union of the pleural and sternal elements in the pterothorax is probably a direct adaptation to the leaping function of the hind legs, but the resulting structure also gives a strong framework for the support of the wings and the wing muscles. The tergal plates are separated from the edges of the pleuro- sternal trough by the ample membranes of the wing bases, and they are thus free to respond to the downward pull of the tergo-sternal muscles. The close union of the terga (fig. 25) and the great size of the dorsal muscles (fig. 34) give efficiency to the latter as elevators of the wings. When the wings are spread they are pivoted on the pleural wing proc- esses by the second axillary sclerites of their bases, and, being closely hinged to the terga by the first and fourth axillaries, they are sharply thrown upward when the tergal plates are depressed, and are turned downward when the terga are elevated. 96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 The mechanism for extending and flexing the wing is highly com- plex. The muscles that produce the movements of extension and flexion depend for their effect on the details of shape and inter-rela- tionships in the axillary sclerites, on the articulation of the sclerites with the tergum and pleuron, on their connections with the bases of the wing veins, and on the structure of the wings themselves. MeN ! | ED ( ae Ax ay) Ua V7 | ——— Fic. 49.—The pleural elements of the wing mechanism in the mesothorax of Dissosteira. a, thickening of cuticular membrane uniting basalar sclerites with humeral angle of wing (see fig. 48) ; 2Ax, second axillary; 34.4, third axillary (first and fourth axillaries removed) ; b, thickening of cuticular membrane uniting subalar sclerite (Sa) with ventral plate (c) of second axillary; Ba, first basalare; c, ventral plate of second axillary resting on pleural wing process (see fig. 48) ; D, flexor muscle of wing, inserted on third axillary; E, pleuro-sternal muscle, or first pronator-extensor of the wing, inserted on basalar sclerite; 1’, episternal pleuro-coxal muscle, or second pronator-extensor of the wing, inserted on basalar sclerite; 1”, epimeral pleuro-coxal muscle, or depressor-extensor of the wing, inserted on subalar sclerite; P/R, pleural ridge; Sa, subalare; tg, tegular rudiment; WW2, base of tegmen, showing dorsal surface. During extension and flexion the wings do not simply turn forward and backward on the pleural wing processes, since each wing is at- tached to the tergum by its entire basal width. The-horizontal move- ments of the wings are made possible mainly by the flexible lines in the wing bases and by the articulations of the axillary sclerites on one another. The working of the parts involved may be easily observed in a freshly killed specimen if the extended wing is slowly flexed. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 97 In the fully exended wing of Dissosteira the axillary sclerites lie approximately flat and in the same plane as the general wing surface (fig. 47 A, B). When the wing is turned posteriorly, however, the axillaries take different positions. In the living grasshopper it is probable that the first movement of flexion is produced by the elas- ticity of the wing base when the extensor muscles are relaxed, for the wing of a dead specimen automatically assumes a partly flexed position. The fully flexed and folded condition, however, undoubtedly depends on the pull of the flexor muscle (fig. 49, D) on the third axillary. On the relaxation of the wing, the initial flexing causes the outer end of the third axillary to turn upward, and the pull of the flexor muscle brings this sclerite to a vertical position. The movement of the third axillary turns the attached median plate (m) likewise to a vertical position on its hinge with the second axillary (24%). In the forewing (A), the revolution of the first median plate (mm) draws the second median plate (m’) inward. The second median plate, however, is firmly attached to the united bases of the median, radial, and sub- costal veins, and the head of the radius (2) is flexibly attached to the anterior end of the second axillary. As a consequence, the movement of the first median plate turns the entire anterior part of the wing posteriorly on the hinge between the radius and the second axillary. But, since the basal connection of this part of the wing forms an oblique line from the head of the first axillary to the articulation between the two median plates, the entire preanal area of the wing is deflected as it turns posteriorly. At the same time, the anal area is lifted but maintains its horizontal plane as the third axillary assumes a vertical position. When the wing finally comes to a longitudinal position over the back, therefore, the anal area is uppermost and the preanal area slants downward on the side (fig. 50 A). During the final revolution of the wing the first axillary turns upward on its hinge with the tergum, the second axillary rotates slightly on the pleural wing process, and the third axillary revolves posteriorly in its vertical position on the fourth axillary. In the hind wing the mechanism of flexion is in general the same as that of the forewing, but, in addition to the posterior turning of the wing, the great anal area is folded fan-like into many plaits. The third axillary of the hind wing (fig. 47 B, 3A) is relatively much larger than that of the forewing (A), its muscle process stands out prominently from the shaft, and the flexor muscle inserted on it con- sists of two bundles of fibers. A distal median plate is lacking in the hind wing, but the single plate (A, m) attached to the third ax- 7 98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 illary affects the anterior group of veins in the same manner as does the corresponding plate of the forewing. When the distal part of the third axillary is lifted by the pull of the flexor muscle, the median plate turns the preanal area of the wing posteriorly and toward the body, and at the same time deflects it to an almost vertical position, with the costal margin downward. The wing surface makes a double fold along the vena dividens (figs. 45 B, 50 B, VD), and the area between the vena dividens and the AR VD Fic. 50.—Positions of the flexed wings of Dissosteira. A, vertical cross-section through fourth abdominal segment, with wings folded over body, seen from behind. B, section of right hind wing more enlarged. IA, 2A, 3A, 7A, first, second, third, and seventh primary anal veins; AF, anal fold; C, costa; 1Cu, first cubitus; 2Cu, second cubitus; /, intercalary vein; 1, 7, secondary veins of first anal plait; k, first concave anal vein; J, second con- cave anal vein; M/, media; R, radius; R + M, combined basal shafts of radius and media; S, sternum; 7, tergum; /D, vena dividens. first principal anal vein (1A) is folded outward beneath the preanal area, with the secondary vein k in the ventral angle of the fold (fig. 50 B). While these maneuvers are taking place in the anterior and middle parts of the wing, the anal fan is bent downward as it comes against the side of the abdomen, and its ventral surface is turned outward beneath the deflected preanal area. The membrane of the fan is plaited between each two of the first seven principal anal veins (fig. 50 B, rd-7A), with the secondary veins occupying the ventral lines of the folds. The posterior part of the fan spreads out against the upper part of the side of the abdomen (A). e NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 99 A careful study of the forms of the folded wings of the grass- hopper, as seen in transverse section (fig. 50), will suggest that many details of structure, both in the tegmina and in the hind wings, are adaptations to the passive state of flexion rather than to the active phases of flight. The extension of the wings is effected probably by the action of both the basalar and the subalar muscles (fig. 49 E, M’ and M”). The basalar sclerites (fig. 48, rBa, 2Ba) are connected by a tough membranous fold (a) with the base of the wing anterior to the wing process. A depression of these sclerites on their episternal articula- tions, caused by the contraction of their muscles (fig. 49, E, M’), must therefore release the flexed wing from its position over the body and turn it outward. The principal extensor of the wing, however, ap- pears to be the muscle of the basalar sclerite (fig. 49, M”). In the flexed wing, the second axillary sclerite is elevated between the first axillary on the one hand, which now stands in a vertical plane on its tergal hinge, and the median plate (mm) on the other, which rises ver- tically from its hinge on the second axillery. The ventral plate of the second axillary is connected with the subalar sclerite by a thickening of the intervening membrane (figs. 48, 49, b). The downward pull of the basalar muscle (fig. 49, M’’) is therefore exerted on the second axillary. It is easy to demonstrate that a downward pressure on the second axillary flattens the entire wing base by restoring the first axillary, the median plate, and the third axillary to, the horizontal plane, and thereby extends the wing. When the wings are extended, the mechanism of flight becomes operative. This includes the direct and indirect muscles, which ac- complish the movements of levation, depression, and rotation, and which have already been described. VI. THE SPIRACELES The generalized ancestors of modern insects possibly had a pair of tracheal invaginations on each of the 17 body segments between the primitive head, or procephalon, and the periproct. Evidence of the existence of such invaginations has been found, however, on only 14 segments, namely, the second maxillary segment, the three tho- racic segments, and the first ten abdominal segments. Tracheal invaginations of the second maxillary segment have been reported by Nelson (1915) to be present in the embryo of the honey- bee. They arise, Nelson says, on the lateral surfaces of the anterior half of the segment above the bases of the rudiments of the second 100 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 maxillae, shortly behind the boundary between the first and second maxillary segments. The second maxillary spiracles have thus the same relative position on their segment as have all the body spiracles in the embryo, or the abdominal spiracles in adult insects. The em- bryonic invaginations of the labial segment, according to Nelson, give rise to a part of the tracheal system of the head, but are later closed and leave no external trace of their existence in the adult insect. Prothoracic spiracles are known to exist as functional organs of the adult only in some of the Sminthuridae (Collembola). They are situated laterally in the neck membrane close to the posterior margin of the head, but Davies (1927) claims that the region bearing the spiracles belongs to the prothorax. These cervical or prothoracic spiracles are the only spiracles present in the Sminthuridae, and no other collembolan is known to possess either spiracles or tracheae in any part of the body. Temporary prothoracic spiracles, followed by the usual series of spiracular invaginations, have been described in the embryo of Blattella by Cholodkowsky (1891), and in the em- bryo of Leptinotarsa by Wheeler (1889). The usual first pair of thoracic spiracles of adult, nymphal,and larval insects is always situated either in the posterior part of the prothorax or in the intersegmental membrane between the prothorax and the mesothorax. In the embryos of most insects, however, these spiracles are said to lie anteriorly in the mesothorax; they would appear, therefore, to be the true mesothoracic spiracles which have become prothoracic in position by a secondary forward migration. The usual second pair of adult thoracic spiracles are the embryonic meta- thoracic spiracles, and they sometimes occur on the anterior part of the metathorax in the adult, though more commonly they lie in the membrane between the mesothorax and the metathorax, or in the posterior part of the mesothorax. The segmental relations of the thoracic spiracles is somewhat complicated by the fact that the muscles of their closing apparatus have their origins in the segments on which the spiracles are situated in the adult. Since, however, the musculature of the thoracic spiracles is not alike in different groups of insects and is often different in the two spiracles of the same insect, it is probably of secondary development in all cases. Contrary to the embryological evidence of the segmental relations of the spiracles, there are many points in the anatomy of the tracheal system, and in the innervation of the spiracular muscles, that suggest, as now claimed by several writers, that the spiracles are primarily intersegmental invaginations, and that their definitive positions are NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS IOI the result of migrations either forward or rearward into the segmental regions of the body. The abdominal spiracles are situated, with few exceptions, on the anterior lateral parts of the abdominal segments, where they lie in the tergal plates, between the terga and the sterna, or in the edges of the sterna. There are usually eight pairs of abdominal spiracles in adult and larval insects, though the number may be variously reduced. There is evidence, however, of more than eight spiracles having been present on the abdomen of primitive insects. Cholod- kowsky (1891) reports the existence of a pair of tracheal invaginations on the first nine abdominal segments of Blattella,and Heymons (1897) says there are apparent rudiments of spiracles on the tenth abdominal segment of Lepisma. In certain insects the spiracles of the first abdominal pair are situated very close to the base of the metathorax, and long discussions recur as to whether these spiracles belong to the thorax or to the abdomen. In all cases, however, it will be found that the spiracles in question lie posterior to the third phragma, which marks the intersegmental line between the metathorax and the first abdominal segment, or behind the lateral extensions of the postnotal plate in the metathorax. The spiracles are therefore abdominal, as is shown also by the destination of their tracheae. The external aperture of a spiracle may be a simple opening leading directly from the exterior into the trachea. In most cases, however, there is a pre-tracheal chamber, or atrium (fig. 53 A, B, Atr), formed by an inflection of the body wall, from the inner end of which arises the trachea (Tra). The atrium of the spiracle, therefore, appears to be a secondary invagination of the body wall, which has carried the mouth of the original tracheal invagination to a more protected position beneath the surface. In some cases the edges of the atrial orifice are elevated to form a pair of protruding lips guarding the entrance (fig. 53 A, c, d), in others the opening is fringed with opposing brushes of hairs, usually thickly branched, or it is itself reduced to a very small diameter. Spiracles are usually provided with a closing apparatus. In the Apterygota the spiracles are said to lack an occlusor mechanism (Du Buisson, 1926; Davies, 1927), and the thoracic spiracles of Plecoptera are simple apertures giving open passages into the tracheae. In general, however, the spiracles have either a device for closing the outer lips of the atrial chamber, or an apparatus for blocking the passage from the atrium into the tracheae. The occlusor mechanism of the abdominal spiracles is of the second type; that of the thoracic 102 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 spiracles may be of similar structure (caterpillars and other larvae), but usually the closing apparatus of the thoracic spiracles in adult insects effects a movement of one or both of the outer lips of the atrial chamber. The Acrididae possess the two usual pairs of thoracic spiracles and eight pairs of abdominal spiracles. The first thoracic spiracle on each side is situated laterally in the ample intersegmental membrane between the prothorax and the mesothorax (fig. 20 B, 26, Sp.) where it is covered externally by the lateral part of the large posterior fold of the protergum (fig. 20 B, Rd). The second spiracle lies in the posterior ventral angle of the mesothoracic epimeron just above the base of the middle leg and immediately before the intersegmental groove between the mesopleuron and the metapleuron (fig. 26, Sps3). The abdominal spiracles are carried by the first eight abdominal terga, each being placed in the lower anterior angle of the corresponding tergal plate. The first of the series, therefore, lies in the tympanal cavity of the first segment, where it is situated on the small triangular area before the tympanal membrane and just in front of the support of the chordotonal organ. All the spiracles are well developed, and each is provided with an efficient closing apparatus, the mechanism of which presents the usual two types of structure, the first pertaining to the thoracic spiracles, the second to the abdominal spiracles. The details of structure, however, are quite different between the two thoracic spiracles. The first thoracic spiracle-—The first spiracle of the thorax of Dis- sosteira carolina is contained in a small, irregular plate, or peritreme (fig. 51 A, Ptr), lying laterally in the intersegmental membrane between the prothorax and mesothorax (fig. 20 B, Sp2), covered externally by the overlapping fold of the protergum. The lower end of the peritreme is produced posteriorly and upward in a small, free process (fig. 51 A, a), bearing on its base a flat-topped, pale-colored tubercle (b) projecting outward. The tubercle is a little higher than the lips of the spiracle and evidently serves as a stop to prevent the covering flap of the protergum from resting too closely against the spiracle. The spiracular opening is an obliquely vertical slit with a slight italic curve and strongly protruding anterior and posterior lips (c, d). The length of the slit is about 0.60 mm. in the male grasshopper, and about 0.75 mm. in the female. The anterior lip (c) is a rigid elevation of the wall of the peritreme; its inner face is soft and deeply grooved parallel with the outer edge. The posterior lip (d) is a weaker and freely-movable flap, but it has a sharp, NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 103 strongly-sclerotized marginal band (¢) which, when the spiracle is closed, fits into the groove of the anterior lip. The cleft of the first spiracle opens into a shallow atrium from which are given off two tracheae, a larger dorsal one (fig. 51 B, f) and a smaller ventral one (g). From without, therefore, the first spiracle appears to have a double opening (A, f, g,). In some of the Orthoptera that have tympanal organs on the front legs, the trachea of the ventral (or posterior) opening of the spiracle appears to have become specialized as an “ acoustic” trachea since it goes only to the Fic. 51.—First thoracic spiracle of Dissosteira. A, outer view of left spiracle. B, inner view of right spiracle. a, ventral lobe of peritreme; b, process of peritreme protecting spiracle from covering flap of pronotum; c, anterior lip of spiracle; d, posterior lip of spiracle; e, hard edge of posterior lip; f, dorsal trachea; g, ventral trachea; h, internal lever of pos- terior lip forming a septum between the tracheae; 7, head of lever on which closing muscle (79) is inserted; /, ventral internal process of peritreme on which spiracular muscles arise; m, external pit forming internal process 1; Ptr, peritreme ; 79, opening muscle; 80, closing muscle. front leg, where it branches into the two tracheae of the tympanal organ. This fact led Graber to the conclusion that the double structure of the first spiracle in Orthoptera originated from the separation of an “‘acoustic”” trachea from the general respiratory tracheae of the prothorax. Carpentier (1924, 1925), however, has shown that the double first spiracle is a character of Orthoptera in general, whether tympanal organs are present in the front legs or not, and that in most forms the tympanal trachea is not isolated from the rest of the respiratory system. The specialization, he says, is carried to its highest degree in the tettigoniid Phasgoneura viridissima, where the spirac- ular orifice of the leg trachea is enormously enlarged. Here, ap- 104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 parently, is a case of an advantage derived by a specific organ from a general structure first developed for some other reason. In the septum between the two spiracular openings in Dissosteira (fig. 51 A, h) is a strong internal bar (B, h) projecting anteriorly and ventrally from the posterior lip of the spiracle, and terminating in a free process (7) that extends anterior to the spiracular opening. Upon this process is inserted a short muscle (79) which has its origin ventrally on an inner process (/) of the lower angle of the peritreme, the site of which is marked externally by a pit (A, m). A second muscle (B, So) arises from the base of the same process (/) and extends. dorsally and posteriorly to its insertion on the base of the posterior lip of the spiracle behind the ventral trachea. The first muscle (79) is the occlusor of the spiracle; the second (80) is evi- dently its antagonist. A downward pull on the head of the septal arm (i), where the anterior muscle is inserted, closes the spiracle by rotating the movable posterior lip forward on its dorsoventral axis and bringing thus its sharp free edge into the groove of the anterior lip. Conversely, a downward pressure on the base of the posterior lip, at the point where the posterior muscle (80) is inserted, rotates the lip in the reverse direction and opens the spiracle. The differential action of the two muscles results from the opposition of their two points of insertion on either side of the long axis of the posterior lip, and is accentuated by the difference in their points of origin on the ventral process (/) of the peritreme. Vinal (1919), Lee (1925), and other writers have regarded both muscles of the first spiracle in Acrididae as occlusors. The second thoracic spiracle—The second thoracic, or metatho- racic, spiracle of Dissosteira is located in the lower, posterior angle of the mesothoracic epimeron of the adult (fig. 26, Sp3), where it is surrounded by a narrow membranous area (fig. 52 A, mb). Externally this spiracle presents two thick, elongate oval, valve-like lips, (fig. 52 A, c, d) separated by a sinuous vertical cleft having a length of about 0.50 mm. in the male insect. Both lips of the second spiracle are movable, though they are united ventrally in a broad lobe (n). The spiracular lips stand out prominently from the body wall (fig. 53, A, c, d), and between them is a shallow atrium (4ér) from which arises a single large trachea (Tra) that soon divides into a dorsal and a ventral branch. The closing mechanism of the second spiracle includes but a single short occlusor muscle (fig. 52 B, ELD) e The muscle arises ventrally from a small process (0) on the posterior dorsal margin of the mesocoxal cavity, and is inserted on the ventral NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 105 lobe (7) of the spiracle. There is no special device for opening this spiracle ; the lips diverge by their own elasticity, as is shown by the fact that the spiracle is always open in a dead insect. The occlusor muscle brings the edges of both lips together. The abdominal spiracles—tThe eight spiracles of the abdomen in Dissosteira are quite different from either of the thoracic spiracles. They are not provided with projecting external lips (fig. 53 B), the body wall being directly inflected in each spiracle to form an open atrial chamber (Atr). The atrium leads by a narrowed aperture at Fic. 52.—Second thoracic spiracle of Dissosteira. A, outer view of left spiracle. B, inner view of right spiracle. c, anterior lip of spiracle; d, posterior lip of spiracle; Epme, epimeron of mesothorax; Eps:, episternum of metathorax; /sg, intersegmental fold; mb, membrane surrounding spiracle; n, ventral lobe of spiracle uniting the lips and giving insertion to spiracular muscle (z1rr); 0, internal lobe on rim of coxal cavity on which spiracular muscle arises; 7, internal intersegmental fold; Tyra, trachea; IZ1, closing muscle of spiracle. its inner end into the spiracular trachea (Tra), and the occlusor mechanism regulates this opening. The longer axis of the first abdominal spiracle is obliquely hori- zontal (fig. 54 A) with the anterior end a little higher than the posterior. The other spiracles (C, D) are placed more nearly vertical, so that the dorsal end of each corresponds with the anterior end of the first spiracle. In each spiracle one wall of the atrium is rigid (fig. 53 B, t), and the other (s) is movable. The rigid wall is dorsal in the first spiracle (fig. 54 A, t) and posterior in the other spiracles (C, D). It is strengthened by a thickening in the external body wall (figs. 53 B, 54 A, #) from which it is inflected. The movable wall of the atrium (s), which is ventral in the first spiracle (fig. 54 A) 106 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 and anterior in the others (C, D), is flexible because the body wall immediately external to it 1s weak, and because the two end walls of the atrial chamber are membranous. The posterior or ventral end of the movable wall is produced into a long, free manubrium (fig. 54 B, D, q) that projects into the body cavity and gives attachment to two muscles, one dorsally, the other ventrally. These muscles, acting antagonistically, either close or open the passage from the atrium into the trachea (fig. 53 B) by means of their attachments on the movable wall of the atrium. The short dorsal muscle of the first abdominal spiracle (fig. 54 B, CMcl) arises on the rim of the tympanum (/) above the spiracle; ? Fic. 53.—Sections of spiracles of Dissosteira. A, longitudinal section through second thoracic spiracle, showing anterior and posterior lips (c, d) as projecting folds of body wall (BW) inclosing an atrium (Atr), or entrance to trachea (Tra). B, vertical section through first abdominal spiracle, showing direct inflection of body wall to form atrial chamber (A?r), of which anterior wall (s) is moy- able, and posterior wall (¢) immovable. Atr, atrium; BW, body wall; c, anterior lip of spiracle; d, posterior lip of spiracle; mb, membrane surrounding lips of spiracle; g, manubrium or muscle process of ventral wall of atrium; 7, intersegmental fold; s, ventral wall of atrium; ¢t, dorsal wall of atrium; 7a, trachea; wu, plate in tergal wall support- ing dorsal wall of atrium. the long, slender ventral muscle (OMcl) arises ventrally on an in- flection of the integument mesad of the hind coxa and posterior to the triangular coxal plate of the metasternum (fig. 30 A, ¢). It is easy to demonstrate that the dorsal muscle (fig. 54 B, CMcl) is the closer of the spiracle and the ventral one (Omcl) the opener. A dorsal pull upon the manubrium (q) of the movable ventral wall of the atrium (s) brings the inner edge of the latter against the inner edge of the fixed dorsal wall (¢) and thus closes the passage from the atrium into the spiracular trachea. By a counter movement the passage is opened. The mechanism of the other abdominal spiracles is the same as that of the first. The short, fan-shaped occlusor muscle (fig. 54 C, D, NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 107 CMcl) arises on the wall of the tergum immediately behind the spiracle, and is inserted on the manubrium of the movable wall of the atrium (gq), which projects ventrally and posteriorly. The long opening muscle (OMcl) arises on the lateral edge of the correspond- ing sternum and extends posteriorly and dorsally to its insertion on the manubrium. Fic. 54.—Abdominal spiracles of Dissosteira. A, first abdominal spiracle, left, outer view. B, inner view of the same spiracle, showing muscles. C, second abdominal spiracle, right, inner view, with tergo- sternal muscles of second abdominal segment. D, eighth abdominal spiracle, right, inner view. CMcl, closing muscle of spiracle; Sp, first abdominal spiracle; J/.S, second abdominal sternum; J/Sp, second abdominal spiracle; OMcL, opening muscle of spiracle; p, anterior margin of tympanal cavity; g, manubrium of ventral or anterior wall of atrial chamber; s, movable ventral or anterior wall of atrial chamber; ¢, fixed dorsal or posterior wall of atrial chamber; u, thickening of tergal wall supporting dorsal or anterior wall of atrial chamber; wv, anterior apodemal arm of abdominal sternum; IIS, eighth abdominal sternum; V JJ] Sp, eighth abdominal spiracle; w, posterior angle of tympanal cavity. The grasshoppers are abdominal breathers. A discussion of the mechanism of respiration would, therefore, lead too far beyond the anatomical limits of the present paper. Recent studies on the breathing of Orthoptera give such varied and conflicting results that we must conclude either that the subject still needs a critical investi- gation or that the insects have no fixed methods of respiration. The weight of evidence is rather in favor of inconsistancy on the part of the insects. 108 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 ABBREVIATIONS USED ON THE FIGURES A, Anal veins. 1A, 2A, etc., first anal, second anal, etc. Ac, antecosta. acs, antecostal suture. Acx, precoxal bridge. AF, anal fold. ANP, anterior notal wing process. Ap, apodeme. Ar, arolium. Atr, atrium. Aw, prealar arm of tergum. Ax, axillary sclerite. 14x, 2Ax, 34x, 4Ax, first, second, third, and fourth axillaries. AxC, axillary cord. Ba, basalare. Bc, basicosta, basal ridge of coxa. bcs, basicostal suture of coxa. Bcx, basicoxite. Brn, branchia, gill. Bs, basisternum. BW, body wall. CMcl, closing muscle of spiracle. cpl, supra-coxal plate of subcoxa. Cu, cubitus. 1Cu, 2Cu, first and second cubitus. Cv, cervix, neck. Icv, 2cv, first and second lateral cer- vical sclerites. Cx, coxa. CxC, coxal cavity. CxP, pleural coxal process. Cxpd, coxopodite. cxs, coxal suture. D, flexor muscle of wing. DMcl, dorsal longitudinal muscles. E, basalar-sternal muscle. Em, lateral emargination of tergum. Endp, endopodite. Epm, epimeron. Eppd, epipodite. Eps, episternum. Eupl, eupleuron. Eutn, entrochantin. Expd, exopodite. Fim, femur. Fu, furca. H, head. /, intercalary vein. tergal promotor muscle of coxa. /-XI, abdominal segments. [S-XIS, abdominal sterna. Isg, intersegmental fold. ISp, IIS p, first and second abdominal spiracles. Ist, intersternite. IT-XIT, abdominal terga. J, tergal remotor muscle of coxa. Ju, jugal area of wing. K, sternal promotor, anterior rotator of coxa. [legs sternal remotor, posterior rotator of coxa. LB, leg basis. Ls, laterosternite. M, media. abductor muscle of coxa. m, m’, distal median plates. M', basalar-coxal muscle. M”, subalar-coxal muscle. Ib, secondary intersegmental mem- brane. mb, membrane Mer, meron. N, N’, adductor muscle of coxa. O, levator muscle of trochanter. OMcl, opening muscle of spiracle. P, body branch of depressor muscle of trochanter. Pak, parapsidal ridge. pas, parapsidal suture. Pc, precosta. NO. 2 Pcx, precoxal bridge. Ph, phragma. rPh, 2Ph, 3Ph, first, second, and third phragmata. PI, pleuron. pl, pleural sclerites between tergum and subcoxa. PIA, pleural apophysis. Pln, planta. PIR, pleural ridge. PIS, pleural suture. PN, postnotum. PNP, posterior notal wing process. Poc, postocciput. PoR, postoccipital ridge. Ppct, prepectus. Ppt, periproct. PR, prescutal ridge. Pra, preanal area of wing. Ps, presternum. ps, prescutal suture. Psc, prescutum. PT, posterior arm of tentorium. Ptar, pretarsus. Ptr, peritreme. Pw, postalar arm of postnotum. QO, coxal branch of depressor muscle of trochanter. R, radius. Rd, posterior fold, reduplication, of tergum. S, levator muscle of tibia sternum. SA, sternal apophysis. Sa, subalare. sa, external pit of sternal apophysis. Sc, subcosta. Scl, scutellum. scl, subdivision of scutellum. THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 109 Sct, scutum. sct, subdivision of scutum. Scx, subcoxa. ST, sternellum. Sp, spiracle. Sp, Sps, first and second thoracic spiracles. Spn, spina. spn, external pit of spina. Ss, spinasternum. Stn, primary segmental sternite. T, depressor muscle of tibia. tergum. Tar, tarsus. Tb, tibia. tg, tegular rudiment. TmMcl, tympanal muscle. Tn, trochantin. Tr, trochanter. r7r, 277, first and second trochanters. Tra, trachea. U, levator muscle of tarsus. Uf, unguifer of tarsus. Un, unguis, claw. Utr, unguitractor plate. l’, depressor muscle of tarsus. VD, vena dividens. VIIISp, eighth abdominal spiracle. VMcl, ventral longitudinal muscle. VR, ridge between scutum and scu- tellum. vs, scuto-scutellar suture. W, wing. WP, pleural wing process. X, depressor muscle of pretarsus, re- tractor of claws. REFERENCES Bauer, A. (1910). Die Muskulatur von Dytiscus marginalis. Zeitschr. wiss. Zool., 95: 594-646, 19 figs. Also in Korschelt (1924), Chapter 12. Becker, E. (1923). Zum Bau und zur Genese des coxotrochanteralen Teiles des Ateloceratenbeins. Zool. Anz., 57: 137-144, 4 figs. — (1924). Zur morphologische Bedeutung der Pleuren bei Ateloceraten. Zool. Anz., 60: 169-185, 6 figs. BervesE, A. (1909). Gli insetti, Vol. 1. Milan. Tio SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 — (1910). Monografia dei Myrientomata. Redia, 6: 1-182, pls. 1-17. Du Butsson, M. (1926). Observationes sur la ventilation trachéene des insectes (3me Note). Bull., Cl. Sci., Acad. Roy. Belgique, 5th Ser., 12: 127-138. CAMPBELL, F. L. (1929). The detection and estimation of insect chitin; and the irrelation of chitinization to hardness and pigmentation of the American cockroach, Periplaneta americana L. Ann. Ent. Soc. Amer., 22:401-426. CaRPENTIER, F. (1923). Masculature et squelette chitineus. Mem. Acad. Roy. Belgique, Cl. Sci., Collection in 8°, 7, fasc. 3: 1-56. — (1924). Sur le double stigmate de quelques Orthopteres. Bull. Soc. Entom. Belgique, 6:123-140, 11 figs. — (1925). Sur le double stigmate de quelques Orthopteres (2me Note). Bull, & Ann. Soc. Entom. Belgique, 65:205-208. CuoLopKowsky, N. (1891). Die Embryonalentwicklung von Phyllodromia ° (Blatta) germanica. Mém. Acad. Sci. St. Petersbourg, 7 Ser., 38, No. 5, 120 pp., 6 pls. Comstock, J. H. (1918). The wings of insects. Ithaca, N. Y. Crampton, G. C. (1909). A contribution to the comparative morphology of the thoracic sclerites of insects. Proc. Acad. Nat. Sci. Philadelphia, 1909: 3-54, pls. 1-4. —— (10914). The ground plan of a typical thoracic segment in winged insects. Zool. Ans., 44: 56-67, I fig. —— (1918). The thoracic sclerites of the grasshopper, Dissosteira carolina. Ann. Ent. Soc. Amer., 11: 347-366, pl. 32. —— (1927). The thoracic sclerites and wing bases of the roach, Periplaneta americana, and the basal structures of the wings of insects. Psyche, 34: 59-72, pls. 1-3. Davies, W. M. (1927). On the tracheal system of Collembola, with special reference to that of Sminthurus viridis, Lubb. Quart. Journ. Micr. Sci., 71: 15-30, 6 figs. Du Portre, E. M. (1920). The muscular system of Gryllus assimilis Fabr. Ann. Ent. Soc. Amer., 8:16-52, pls. I-7. DutrKeNn, B. (1907). Die Tracheenkiemenmuskulatur der Ephemeriden unter Beriicksichtigung der Morphologie des Insektenfliigels. Zeitschr. wiss. Zool., 872 435-550, pls. 24-20. Ewrnc, H. E. (1928). The legs and leg-bearing segments of some primitive arthropod groups, with notes on leg-segmentation in the Arachnida. Smuith- soman Misc. Coll., 80, No. 11, 41 pp., 12 pls. Heymons, R. (1897). Entwicklungsgeschichtliche Untersuchungen an Lepisma saccharina L. Zeitschr. wiss. Zool., 62: 583-631, pls. 20, 30. —— (1899). Beitrage zur Morphologie und Entwicklungsgeschichte der Rhyn- choten. Nova Acta. Abh. Kaiserl. Leop.-Carol. Deut. Akad. Naturf., 74: 349-456, pls. 15-17. KorscHELt, E. (1924). Dytiscus marginalis, 2 vols. Leipzig. Lez, M. O. (1925). On the mechanism of respiration in certain Orthoptera. Journ. Exp. Zool., 412125-154. voN LENDENFELD, R. (1881). Der Flug der Libellen. Sitz. Ber. Akad. Wiss. Wien, Math-Natur., 83, Abth. I: 289-376, pls. 1-7. MacGitiivray, A. D. (1923). External insect-anatomy. Urbana, III. MacLeay, W. S. (1830). Explanation of the comparative anatomy of the thorax in winged insects, with a review of the present state of nomen- clature. Zool. Journ., 5 (1835) : 145-179, pls. 5, 6. NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS III Martynov, A. B. (1925). Ueber zwei Grundtypen der Fltugel bei den Insekten und ihre Evolution. Zeitschr. Morph. u. Okol. Tiere, 4:465-501, 24 figs. Mortson, G. D. (1927). The muscles of the adult honey-bee (Apis mellifera L.). Part I. Somatic musculature. Quart. Journ. Micr. Sci., 71%: 395-463, 12 figs. Netson, J. A. (1915). Embryology of the honey bee. Princeton Univ. Press. Prett, H. (1913). Das Chitinskelett von Eosentomon. Zoologica. Orig-Abhandl. Gesamtg. Zool., 25, 58 pp., 6 pls. SHEPARD, H. H. (1930). The pleural and sternal sclerites of the lepidopterous thorax. Ann. Ent. Soc. Amer., 23 (in Press). Snopcrass, R. E. (1909). The thorax of insects and the articulation of the wings. Proc. U. S. Nat. Mus., 36: 511-595, pls. 40-60. —— (1910). The thorax of the Hymenoptera. Proc. U. S. Nat. Mus., 39: 37-91, pls. 1-16. —— (1927). Morphology and mechanism of the insect thorax. Smithsonian Misc. Coll., 80, No. 1, 108 pp., 44 figs. — (1928). Morphology and evolution of the insect head and its appendages. Smithsonian Misc. Coll., 81, No. 3, 158 pp., 57 figs. SPEYER, W. (1922). Die Muskulatur der Larve von Dytiscus marginalis L. Zeitschr. wiss. Zool., 119: 423-492, 21 figs. Also in Korschelt (1924), Chapter 13. Tittyarp, H. J. (1919). The Panorpoid Complex. Pt. 3, The wing-venation. Proc. Linn. Soc. N. S. W., 44: 533-718, pls. 31-35. Vinal, S. C. (1919). The respiratory system of the Carolina locust (Disso- steira carolina Linne). Journ. New York Ent. Soc., 27:19-32, pls. 3-5. Voss, F. (1905). Ueber den Thorax von Gryllus domesticus (Pts. 1-4). Zeitschr. wiss. Zool., 78: 268-521, 645-759, pls. 15, 16, 24. Weber, H. (1924). Das Thorakalskelett der Lepidopteren. Ein Beitrag zur vergleichenden Morphologie des Insektenthorax. Zeitschr. Anat. und Ent- wick., 73: 277-331, 9 figs. — (1925). Der Thorax der Hornisse. Ein Beitrag zur vergleichenden Morphologie des Insektenthorax. Zool. Jahrb., Anat., 47: 1-100, pls. 1-4. — (1927). Die Gliederung der Sternalregion des Tenthredinidenthorax. Zeitschr. wiss. Insektenbiol., 22: 161-108, pls. 1-6. — (1928). Die Gliederung der Sternopleuralregion des Lepidopterenthorax. Eine vergleichend morphologische Studie zur Subcoxaltheorie. Zeitschr. qwiss. Zool., 131: 181-254, 21 figs. — (1928). Skelett, Muskulatur und Darm der schwarzen Blattlaus, Aphis fabae Scop. Zoologica. Orig-Abhandl. Gesamtg. Zool., 28 (Heft 76), 120 pp., 12 pls. — (1929). Kopf und Thorax von Psylla mali Schmidb. (Hemiptera- Homoptera). Eine morphogenetische Studie. Zeitschr. Morph. u. Okol. Tiere, 14 (Heft 1): 59-165, 35 figs. Wueeter, W. M. (1889). The embryology of Blatta germanica and Doryphora decimlineata. Journ. Morph., 3: 291-386, pls. 15-21. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 3 Hodgkins Fund THE RADIATION OF THE PLANET BARTH TO SPACE (WitTH Two PLATEs) BY C. G. ABBOT (PUBLICATION 3028) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION NOVEMBER 16, 1929 The Lord Baltimore Preas BALTIMORE, MD., U. 3. A. bovgkins Fund THE RADIATION OF THE PLANET EARTH TO SPACE By C. G. ABBOT (Wira Two Prates) In an illuminating series of papers, G. C. Simpson recently has approached the subject of terrestrial and atmospheric radiation to outer space. The first of these papers is entitled “Some Studies in Terrestrial Radiation.” * Here Simpson makes the unsatisfactory assumption that the atmospheric water vapor behaves like a “ grey body ” in absorbing radiation. That is, he assumes that general coefh- cients of absorption and of transmission may be employed, without regard to the wave length of the radiation considered. Arriving in this way at unexpected and questionable results, Simpson then modi- fied his procedure in a second paper entitled “ Further Studies in Ter- restrial Radiation.” * Here he makes the following important assump- tions: (a) The stratosphere contains 0.3 mm. of precipitable water. (b) The absorptive properties of atmospheric water vapor may be regarded as so similar to those of steam that Hettner’s * observations of the absorption of a layer of steam may be taken as representing the coefficients of absorption of atmospheric water vapor between wave lengths 4» and 34.’ (c) “The stratosphere absorbs all radiation between wave lengths 54 and 7p, and from wave length 14, to the end of the spectrum.” As the Smithsonian Institution has hitherto published considerable evidence relating to these three subjects, it has occurred to me to see whether the use of our independently derived data would check well the ‘ * Mem. Roy. Meteorol. Soc., Vol. 2, No. 16, 1928. * Ibid., Vol. 3, No. 21, 1928. *Hettner, G., Ann. Physik. Leipzig, 4th Folge., Band 55, p. 476, 1918. “Simpson nevertheless calls attention to the incomplete similarity between the absorption of concentrated and unconcentrated vapors, and therefore cor- rects Hettner’s curve between 8 and t1u from other data derived from atmos- pheric experiments. SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 3. 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 results of Simpson in this important field. Fowle’ carried on for several years, 1908 to 1917, experiments on the absorption of radiation of long wave lengths by the atmosphere contained in tubes of large diameter and up to 800 ft. in length. These tubes were laden with water vapor ranging from 0.2 up to 2.5 mm. of precipitable water, and of carbon dioxide content ranging from 7 grams up to 160 grams per meter cross-section at normal temperature and pressure. In his early experiments, Fowle had established means for deter- mining the quantity of precipitable water in atmospheric air by means of measurements on the bands por, ¢, and w of the upper infra-red solar spectrum. These experiments are fortunately very definite as to the determination of water vapor equivalent to 0.3 mm. of pre- cipitable water. In the summer of the years 1909 and 1910, Abbot observed the infra-red solar spectrum from Mount Whitney, California, altitude 4,420 m. Bolographs of the spectrum were obtained, having very satisfactory quality as far as the delineation of the bands por, ¢, and y is concerned.” From these, Fowle determined the quantity of total precipitable water in a vertical path of atmosphere above Mount Whitney. On August 14, 1910, he observed 0.6 mm. Considering the moderate altitude and the summer season, this small observed water- vapor content hardly prepares one to accept Simpson’s assumption that the stratosphere, which begins at 12,000 m., and is at a tempera- ture about 50° C. lower than that which prevailed at the summit of Mount Whitney on that occasion, can contain half of the precipitable water above that station. We have other evidence leading to the same view. At Mount Montezuma, Chile, altitude 2,710 m., we have observed spectroscopically the total precipitable water in a vertical column above the station almost daily for about 10 years at all seasons. The following table gives average values for the 12 months, and also extreme values for each of these months, together with associated surface temperatures. In illustration of the great alterations in the appearance of the solar energy spectrum depending on the quantity of atmospheric humidity, we give reproductions of two days’ observations at Montezuma, plates 1 and 2. Note the bands por, ¢, y and Q. *Fowle, F. E., Ann. Astrophys. Observ., Vol. 4, pp. 274-286. Astrophys. Journ., Vol. 38, p. 303, 1913; Vol. 42, p. 304, 1915. Smithsonian Misc. Coll., Vol. 68, No. 8, 1917. * See Annals, Vol. 4, fig. 50. ise) ABBOT EARTH TO SPACE RADIATION OF NO. 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DE el aa ee qo Oo Fé gl‘z goo Lz61 br! bz61 too Fil 63°0 o-LI ‘uel “wut 80 Ga) "mo 08 60) SULTS): 00 9) “Wo WINUWITXeUul WMNUWITUTUT WINUITXPUl PUWIIXeUL WNUITUTU eUIIUTUI sAep Qz6I-£261 "ml °e 1odea O1‘o ueyy Ajrep Ayrep aynyjosqe aynjosqe aynjosqe aynyjosqe jo ‘ou sivad YIO]I,0 g snoonbe SSo] Son[vA awyposqy eynyposqy JO APA jo uvoyy jO IB9KR jo uvo]y [RIO L jo uvoIN qinq Quo ainssaid | sAep jo"oN Aip uv soe pins $761 1e9h SIoJOUIIJUID Ul 19jVAA VIGeWAIOeIg Joy ‘dway 9ZzOr of E261 savaX ‘punzajuopy qv synsay uvayy KyyJuopyY—'l ATAV J, 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 From the tabular data, it is clear that values of total precipitable water are frequently observed at Montezuma closely approaching the value assumed ,by Simpson for the stratosphere. These values are found in winter, with a surface air temperature of +9° C., on the edge of the tropics at 2,710 m. altitude. In view of these observations at Montezuma, and considering the rapid decrease of humidity with temperature (the vapor pressure at —50° and o° C. being respectively 0.03 and 4.58 mm.) and also the fact that three-fourths of the superincumbent atmosphere lies’ between Montezuma station and the bottom of the stratosphere, one is forced to conclude that the value of the precipitable water contained by the stratosphere is vanishingly small, rather than 0.3 mm. as assumed by Simpson. This materially affects his argument, especially that part which relates to cloudy skies. As an independent approach, instead of Simpson’s two other basic assumptions, which we have designated as (b) and (c), we have em- ployed Fowle’s two summaries of the results obtained in his long-tube experiments. To make these results of Fowle’s applicable to the problem of atmospheric radiation and absorption, as set by Simpson, we have prepared a large scale plot, reproduced in reduced size in figure 1. From this plot we take table 2. In choosing the quantities of precipitable water to be used, we have doubled the values given by Simpson for successive layers in the table he designates as “ Fig. I,” page 72, of his paper “‘ Some Studies in Terrestrial Radiation.” This doubling we do because of the following consideration. . We are proposing to ascertain the radiation which certain layers of the free atmosphere, containing natural loads of water vapor and car- bon dioxide, will send upwards in all directions within a solid angle filling a complete hemisphere. We assume, as does Simpson, that for monochromatic rays the emission of such a layer bears the same pro- portion to the emission of the perfect radiator that the absorption of the layer in question bears to unity. While some rays are emitted ver- tically, most rays are emitted obliquely, so that the average emission and absorption of a layer exceeds that which corresponds to the pre- cipitable water vapor and carbon dioxide found in a vertical path. It is readily proved by performing the integration over a complete hemisphere that the average upward path is double the vertical one. Hence we have doubled Simpson’s figures for the precipitable water contained in the layers he has chosen. These data appear in table 2. *See Annals, Vol. 4, Table 102, p. 286; also Smithsonian Physical Tables, 7th Rey. Ed., 4th reprint, p. 308. RADIATION OF EARTH TO SPACE—ABBOT Say Seas or 2 CAC erie ae Te 7 aT oy Fee MT Er Te id er TY tot Pa ea ae ean Say ae Poy Bl beezckohob AT] EEOC ACT ony an@ ae Sran ara OO ues} 98p,u99 42q Fowle. ) . (After and Carbonic Acid Gas with Water Vapor ion of Radiation by Air Laden m 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 As a second step, we consider the spectral distribution and intensity of emission of the perfect radiator at different temperatures.’ By interpolation on large scale plots we have prepared table 3. This gives the approximate ° intensity of emission of the perfect radiator at tem- peratures corresponding to the mean temperatures of Simpson’s lay- ers, and to those of his selected latitudes of the earth’s surface. Multiplying the values in table 2 by corresponding ones in table 3, we obtain the emission of radiation outwards from each Simpson at- mospheric layer towards a complete hemisphere. The values are given in table 4. Again interpolating in the plots (fig. 3) we next obtained the trans- mission coefficients for each superincumbent atmospheric mass lying above the respective Simpson layers. Allowance is made for the ozone absorption between Qu and I1p. These values are given in table 5. Multiplying these values by corresponding ones in tables 3 and 4, we obtained the contributions of the Simpson atmospheric layers and also of the earth’s surface * at the latitudes go°, 70°, 60°, 50°, 40°, and o° to the intensity of emission of the earth as a planet towards outer space.’ These results are given in table 6. All of these results apply to cloudless skies. We now assume, with Simpson, that the earth is 50 per cent cloudy; that the clouds totally absorb all radiation arising from beneath them ; that they radiate quite as efficiently as the perfect radiator; and that their upper surfaces maintain the same average temperature as the earth at 70° latitude. Weare not able to compute their radiation in Simpson’s manner, since we have shown reasons to believe that the stratosphere is almost desti- tute of water vapor, instead of containing 0.3 mm. of precipitable water as he supposes. We simply assume that the combined emission of clouds and atmosphere during one-half the time at all latitudes is the same as that of the earth’s surface and the superincumbent atmos- phere at latitude 70°. That is: For the atmosphere 0.151 cal. per cm. per min. ; for the cloud surface 0.100 cal., giving a total for com- pletely overcast sky of 0.251 cal. During the other half of the time, *See Smithsonian Physical Tables, p. 248. *We do not guarantee these values to within 2 per cent. *We assume, with Simpson, that the earth’s surface may be regarded as a perfect radiator. * Notwithstanding our previous evidence that the water-vapor content of the stratosphere is vanishingly small, we have thought best to estimate 30 per cent of black-body efficiency as applicable to the stratospheric radiation in the wave-length region 13” to 504, where water vapor is so very active. We have allowed 16 per cent of black body efficiency to the ozone band, ou to 11m. 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(e|.6. 6. 6B. 88. 628 am 040, 6) S.ban 9 (9) (0) L'6g (0) (0) v'Igi fegr S*2S1 g Ly1 Vivi 6ge os I'vi Ce EN iii Sees) OB LINIGS ogi 9'gt gOLl S*gtz z°£9Q ve /fpa oll 9°60 gl £'oL v'Sz gi > oo UGSOUIT TY, :3jOd re) oO Tet He oO re) ve Pr 'I oO ALS 8 6L LES o'9 4, ‘sire (e\.e) baiave ‘see ole el6 e.8 ¢ oO (6) 9°08 (a) Oo is) is) oO (6) vz I'gt gy oe Pee Ne ee a CONT acta eC tua v is) Oo 8°98 I'v (0) Oo (0) (a) (a) (a) avr Ls v'z Ce ¢ 0 0 0°96 OIE 0 0 0 0 0 0 oor 9'S oe ee stere tan exee z () to) 9°36 vz ° oO Oo fs) oO Oo 6 ce g'0 One CHPEC COR CCP CUpeare ns I (o) (0) 3°30 cece (0) io) (9) io) Oo (o) oz Ql cA 0 MD Te oe ea a ae I— (s) to) S°16 f-zs ro) (0) fo) oO (e) (s) (6) vo TSO, Ale Sao PROS See eles ~— rs Paes eee 0 0 9's Zee 0 0 oO 0 0 0 zo 10 0:0 Sear iny a I've O°gI 9'3t Q°gil £'°gl z'eg Pee Cc (Cece irra ac ny 9°6 9°6 «fe we ehe.aie)|\s ale) vier eie.sil\m ataahe eke 9 |\aal ere 20) e siiifee ale, eka) areas in. ala) sii araydsozes3s oS—ov ob—of of£-0z 0z-91 gI-£1 €1-zI zI-II II-O1 o1-6 6-g g-L L-9 9-s IDART SIFIOL uosdulig SUOIDIUI ‘SYABUI] VALAA (1000° Aq Ajdiypnu “ur sad ,wio Jad ‘[ed 0} aonpas OF) YS ssappnojzy ysnosyy a2pgG 4ajnQ suryrDay UuoYDIpoy a2Dfangy pup I4aydsou4p—9 ATAV I2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 the values at different latitudes are as given in table 6 for clear skies. For half-cloudy skies we take the mean of the two conditions. We are now prepared to assemble our results and compare them with those of Simpson (table 7). It is clear that our employment to a considerable extent of inde- pendent data and methods has made no very great difference in the totals from those of Simpson. The range of our totals for half- cloudy sky is indeed considerably greater than his as between the equator and the poles. Our method has enabled us to segregate the contributions of the atmosphere and of the earth’s surface, which in Simpson’s second paper are not computed separately. We find the earth’s surface almost equally contributing at all latitudes, but the TABLE 7.—Radiation of Earth and Atmosphere to Space Calories per cm.” per min. Smithsonian results Simpson results Latitude Clear sky Half-cloudy sky Atmosphere plus surface Atmos-} Sur- Atmos- | Surface Over- | Half- phere face Total phere jor cloud Total | Clear cast | cloudy ORS aiseeee 0.220 | 0.105 | 0.325 | 0.186 | 0.102 | 0.288 | 0.316 | 0.213 | 0.264 AO": 0.192 | 0.107 | 0.299 | 0.171 | 0.103 | 0.274 | 0.307 | 0.243 | 0.275 BO ne. eee 0.182 | 0.105 | 0.287 | 0.166 | 0.102 | 0.268 | 0.291 | 0.249 | 0.270 GOo teres 0.162 | 0.104 | 0.266 | 0.156 | 0.102 | 0.258 | 0.274 | 0.252 | 0.265 [Ae seeks heecyt 0.151 | 0.100 | 0.251 | 0.151 | 0.100 | 0.251 | 0.253 | 0.253 | 0.253 QOS ae 0.129 | 0.096 | 0.225 | 0.140 | 0.098 | 0.238 0.245 atmosphere, which contributes much more than half the total (even more than two-thirds the total on cloudless days at the equator) emits very much lesser proportions as we approach the poles. The two sources are very different as regards wave lengths of principal contri- bution ; the atmosphere emitting mostly in the region exceeding I6p in wave length, the surface emitting principally in the region Op to I3u. If we sum up the results in the seventh and tenth columns, which represent our own and Simpson’s totals for half-cloudy sky, and as- sign weights to them proportional to the areas of earth which they respectively represent, we find that the earth as a planet radiates aver- ages of 0.277 or 0.265 cal. per square centimeter per minute according as our results or Simpson’s are taken. If we compute the same quan- tity from the solar constant, 1.94 cal., and Aldrich’s albedo, 43 per Ray ; : cent, the result aa <0.57=0.276 cal. The discrepancies are very small and far within the probable error of the determinations. he — wen a EC KC ee r7, MY | | i } , | ‘ { \ } b ] ' \ i ; | rn | ‘ | ‘ ‘ ' iT ' \ A | ’ \ | y ‘ pe — : Fad —_— —_-- A P Se ae *. _— mer — — — _— — ray _ v | : ee | — ——— _ —_—_— a os —_=—-—" _- be allen - —e)e- - ee _ _ — - 7 v Visible oe Ue 1a! for ima i u VOL. 82 NO. 3, PL. 2 My ‘ WA av elated ORE, a= = <=> nee ee f = Visible — ———_————_»— Ul tra-violet ———_> \ ‘ PO\Wi 4 \ A vw “N t APS cw! aL ‘ A ‘ ‘ Ss wo —- + 4--*- = nn aa ; My) é ee ¥ ‘ i mee Weta tr) Ge. Vie Val NS eh N v 2 SS - ee ae lS (8) SLO aaa pos Be eee Me cat WP es a ed ee ee Infra-red SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 4 THE CHARACTERS OF THE GENUS GEOCAPROMYS CHAPMAN (WitTH ONE PLATE) BY GERRIT S. MILLER, JR Curator, Division of Mammals, U.S. National Museum YALA VP. e 4A; THSOBSS,. Le UIT TN po iw a ae (PUBLICATION 3029) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION DECEMBER 9, 1929 The Lord Baltimore Press BALTIMORE, MD., U. 8. A. THE CHARACTERS OF THE GENUS GEOCAPROMYS CHAPMAN By GERRIT S. MILLER, JR. CURATOR, DIVISION OF MAMMALS, U. S. NATIONAL MUSEUM (WitH ONE PLATE) In his “ Revision of the Genus Capromys”’ (Bull. Amer. Mus. Nat. Hist., Vol. 14, pp. 313-323, Nov. 12, 1901) Mr. Frank M. Chapman established a sub-genus Geocapromys (p. 314) to include Capromys brown J. B. Fischer, C. thoracatus True and C. ingrahami J. A. Allen, animals that were supposed to have skulls and teeth essentially like those of the species of true Capromys, but to have unusually short tails and poorly developed thumbs. Sixteen years later Dr. Glover M. Allen raised Geocapromys to generic rank and added to its characters the presence of a small supplemental reentrant angle near the front of the lingual side of the first mandibular molariform tooth (Bull. Mus. Comp. Zool. Vol. 61, p. 9, Jan., 1917). In 1919 Mr. H. E. Anthony noticed that the course of the upper incisor of Geocapromys is clearly shown on the face of the maxillary as a prominent swelling on the wall of the antorbital foramen, while in Capromys no such swelling is present (Bull. Amer. Mus. Nat. Hist., Vol. 41, p. 631, Dec. 30, 1919). In his 1917 paper Dr. Allen, misled by Chapman’s imperfect specimens of Geocapromys columbianus, made his own better material of the Cuban animal the basis of the new name G. cubanus (p. 9), and proposed (p. 5) the generic name Synodontomys for the original C. columbianus. These errors he later recognized and corrected (Bull. Mus. Comp. :Zool., Vol. 62, p. 145, May, 1918). When preparing the copy for my “ List of North American Recent Mammals 1923” I concluded that the dental features pointed out by Allen and Anthony did not warrant the generic separation of the group from Capromys. Not knowing of any other characters I relegated Geocapromys to subgeneric rank again. More recently, while examining broken skulls from caves in Cuba, I found that there are important and constantly present features of both skull structure and tooth arrangement that fully justify the generic separation of the ‘two groups. The diagnostic characters may be tabulated as follows: * SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 4 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 Preorbital bar of maxillary sloping obviously forward; root capsule of upper incisor terminating in contact with outer half of an- terior border of alveolus of pm*; bases of alveoli of right and left pm* separate, not encroaching on floor of narial passage ; pm: with only two reentrant angles on lingual side.............. Capromys Preorbital bar of maxillary vertical or sloping slightly backward; root capsule of upper incisor terminating above and ectad to anterior half of outer border of alveolus of pm‘; bases of alveoli of right and left pm* in contact, encroaching on floor of narial passage; pm, with a small third reentrant angle on lingual Side psoas Rhtes Soke era edi eked east epee Ra ea RY 3 ate eels oar Geocapromys REMARKS ON GEOCAPROMYS Skull—The ascending branch of the maxillary dividing the orbit from the antorbital foramen is vertical (G. ingraham) or backward- sloping (G. brownii and G. thoracatus) in relation to alveolar line instead of conspicuously forward-sloping as in Capromys (pl. I, figs. I and 2). By this character alone any one of the three living species can be distinguished from any of the four living Capromys. (I have not seen a specimen of the extinct G. columbianus in which the as- cending branch is preserved). The backward slope in Geocapromys is never so strong as the forward slope in Capromys, but the difference is obvious when the general direction of the ascending branch is com- pared with the line of the alveolar margin. Teeth—Root of upper incisor encapsuled in the lower half of the maxillary wall of the antorbital foramen (see pl. 1, fig 1), the dis- tance between the outer surfaces of the very obvious incisor capsules of opposite sides greater than that between the outer sides of the basal capsules of the opposite first molars. In Capromys the root of the incisor terminates opposite the antero-inner edge of the lower lip of the antorbital foramen (pl. I, fig. 2), and the transverse diam- eter of the rostrum through the scarcely evident capsules is less than that through the bases of the first molars. The base of pm‘, which is hidden by the incisor capsule in Geocapromys, often forms an obvious external swelling in Capromys (as in pl. 1, fig. 2). These characters indicate that the members of the two genera have been developing along consistently different lines. In Capromys the incisor root has pushed back to a position where more advance is prevented by contact with the base of pm‘; in Geocapromys its posi- tion is such that it could be extended much farther back in a capsule lying along the outer surface of the molar shafts as in Spalacopus.: The Capromys condition is nearly paralleled in Octodontomys. In correlation with the position of the incisor roots the molar roots are NO. 4 THE GENUS GEOCAPROMYS CHAPMAN—MILLER 3 farther apart in Capromys than in Geocapromys. This character is not visible in complete skulls, but is evident in the broken-away palates so often found in caves. The upper surface of such a fragment of the maxillary (lower floor of nares) in the region between the anterior zygomatic roots is traversed by a deep median sulcus in Capromys occupying the space between the rather widely separated bases of the opposite premolars ; in Geocapromys there is no median sulcus between the premolars, but the maxillary rises as a broad flat plate to the level of the connate bases of these teeth. Immediately behind this level the groove begins, passing backward to the posterior nares between the progressively more separated roots of the molars. The genus Geocapromys contains four species—the living G. brownii (Fischer) of Jamaica, G. thoracatus (True) of Little Swan Island, Gulf of Honduras, G. ingrahami (Allen) of Plana Keys, Bahamas, and the extinct though geologically Recent G. columbianus (Chap- man) of Cuba (with its synonym G. cubanus G. M. Allen). EXPLANATION OF PLATE All figures natural size Fic. 1. Geocapromys brownti (Fischer). Adult female. No. 143851, U. S. Nat. Mus. Jamaica. i= base of incisor capsule. Fic. 1a. Geocapromys browniit (Fischer). Adult male. No. 141908, U. S. Nat. Mus. Jamaica. Palate cut away from skull and viewed from above. pm = base of premolar, i= base of incisor capsule. Fic. 2. Capromys pilorides Desmarest. Small individual, No. 103884, U. S. Nat. Mus. Cuba. pm —=capsule at base of premolar, i= base of incisor capsule. Fic. 2a. Capromys pilorides Desmarest. Large individual. No. 253232, U. S. Nat. Mus. Palate cut away from skull and viewed from above. pm = base of premolar, i= base of incisor capsule. Fic. 2b. Capromys sp. No. 254679, U. S. Nat. Mus. Cuba (cave deposit). Palate cut away from skull and viewed from above. pm = base of premolar, 1 = base of incisor capsule. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLE S2 NO 4 on Pleeed 1. Geocapromys. 2. Capromys. (All figures natural size) SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 5 MAMMALS EATEN BY INDIANS, OWLS, AND SPANIARDS IN THE COAST REGION OF THE DOMINICAN REPUBLIC (WiTH Two PtatTEs) BY GERRIT S. MILLER, JR. Curator, Division of Mammals, U.S. National Museum qnaenneseeee Zant NCRes <2 OCEAN : ry << N (PUBLICATION 3030) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION DEGEMBER 11, 1929 The Bord Baftimore Press BALTIMORE, MD., U. 8. A. MAMMALS EATEN BY INDIANS, OWLS, AND SPANIARDS IN THE COAST REGION OF THE DOMINICAN REPUBLIC By GERRIT S. MILLER, JR. CURATOR, DIVISION OF MAMMALS, U. S. NATIONAL MUSEUM (WitTH Two PtatTes) In February and March, 1928, I visited the Samana Bay region, northeastern Dominican Republic with the special object of obtaining remains of mammals in the Indian deposits that had been previously examined by Gabb in 1869-1871 and Abbott in 1916-1923. I was accompanied by Mr. H. W. Krieger, who had charge of the strictly ethnological side of the work. Together or separately we obtained material from six localities: four on the south shore of Samana Bay ; one, Anadel, near Samana town, on the north shore of the bay; and one, a large Indian site at the mouth of the Rio San Juan, on the Atlantic coast, across the peninsula from Samana.’ Mr. Krieger re- turned alone the following winter and revisited the places that we had previously worked. He also made excavations in two village sites not far from Monte Cristi at the northeastern extremity of the Republic. At all of these localities we obtained many bones of mammals from the heaps of Indian refuse. Only once, however, in a lateral recess about half way up the sloping floor of the cave that occupies most of the islet of San Gabriel, off the south shore of the bay, did we find an owl-made deposit of extinct mammals. Here, as at St. Michel, Haiti, the small living barn owl had plentifully bestrewn the surface with dejecta containing bones of bats, small birds, and the introduced European rats and mice. Immediately beneath its surface the cave floor material was intermingled with the bones of the larger native rodents that had been devoured by the great extinct owl. This deposit was not more than two feet deep, and, unlike the kitchenmidden lying in the lower level of the cave, it was considerably hardened *A general account of this work was published in Expl. and Field-Work Smithsonian Inst., 1928, Smithsonian Publ. No. 3011, pp. 43-54, March 22, 1929. SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 5 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 by infiltrated lime drip.* Other owl deposits of the same kind may have once existed in the neighboring caves, but if so, they all appear to have been removed years ago by guano diggers. The specimens that we obtained in these caves and village sites form the subject matter of the present paper. While no hitherto unknown species are represented in our col- lections the material proves to be of much interest. It throws ad- ditional light on the characters and distribution of the two species of Plagiodontia that I recognized in 1927 as occurring in the Dominican Republic (Proc. U. S. Nat. Mus., Vol. 72; Art. 16, pp. 1-8, Sept. 30; 1927) ; it furnishes the means to identify all four of the native mam- mals, the hutia, the quemi, the mohuy and the cori, that Oviedo said were habitually eaten by both natives and Spaniards during the early years of the sixteenth century ; and finally it shows beyond the possi- bility of reasonable doubt that this recently extinct fauna included a ground sloth. The identity of only two of the mammals that Oviedo ascribed to the island of Hispaniola remains to be determined—the “ dumb dog ”’ and the indigenous rat. The few dog bones collected appear to differ in no way from the corresponding parts of European dogs, and there is nothing to prove that they represent the native breed. Hence the status of the famous “ perro mudo,” the dog that was unable to bark, is still as much of a mystery as ever. Equally obscure is the question as to whether or not there were rats on the island at the time of its discovery. Oviedo relates that on inquiring into this matter he found those who told him that “mures 6 ratones” did in fact then exist; a circumstance that appeared to him quite believable because these animals were so well known to be generated, like flies, mosquitoes, wasps, and grubs, anywhere, out of any kind of putrifying matter, a not unnatural belief at the time when he wrote, more than 125 years before Francisco Redi had published his “ Esperienze Intorno Alla Generazione Degl’ Insetti.” Nevertheless our search has failed to reveal a trace of rats or mice other than the European species that could have easily been brought by the Spaniards on their ships. After enumerating the specimens that we obtained I shall return to the sub- ject of Oviedo’s mammals in greater detail. DESCRIPTION OF COLLECTING STATIONS 1. Railroad cave—A large cave situated about 15 minutes walk inland along the abandoned railroad on the south shore of San Lorenzo Bay. There is an extensive kitchenmidden at the entrance. I was not able to find any trace of a bone deposit made by the extinct owl, NO. 5 MAMMALS FROM DOMINICAN REPUBLIC——-MILLER 3 though pellets of the living bird were abundant in one of the chambers. This may be the “ Cueva del Templo” of Rodriguez (Geografia fisica, politica e historica de la Isla de Santo Domingo o Haiti, p. 367, Santo Domingo City, 1915). 2. Boca del Infierno—Two large caves, one in each of the pro- jecting points at the locality marked Pta. de Boca del Infierno on the Hydrographic Office chart of Samana Bay. The larger cave is in the smaller, inner point. It has been extensively worked for guano, but some of the original floor material remains. Near the outer entrance there is a small kitchenmidden. A few leg bones of extinct rodents were found in this cave, but no skulls or jaws. At the inner entrance to the other cave we found the remnant of a kitchenmidden left intact by the guano diggers. From this deposit we unearthed bones of both the “quemi” and the ground sloth, mammals whose remains have not been found elsewhere among the Indian refuse. These caves appear to be, respectively, the “ Boca del Infierno”’ and the “Cueva del Infierno”’ of Rodriguez. It is probable that in one or the other of them Gabb collected the bones of Plagiodontia that I recorded in 1916. 3. San Gabriel—An islet about two miles west of Boca del Infierno. Most of its interior is occupied by a large cave, the floor of which slopes rather steeply upward from an opening on the south side facing the shore to another on the north side overlooking Samana Bay. There is a large kitchenmidden near the lower entrance, and a deposit made by the extinct owl on the left side of the passage leading up to the north aperture. 4. Rio Naranjo Abajo—A kitchenmidden was found on a nearly level rock ledge, perhaps one-fourth acre in extent, on a key lying about half a mile east of the stream mouth. These four localities are all on the south shore of Samana Bay in the region known as the Playa Honda coast. Rodriguez describes the caves under the general title: “ Cuevas de los Haitis.” 5. Anadel.—A large village site at a stream mouth on the north shore of Samana Bay about 14 miles east of Santa Barbara de Samana. 6. Rio San Juan—Another large village site on the Samana Penin- sula. It lies at the point where the Rio San Juan flows into the Atlantic Ocean, almost directly north of Santa Barbara de Samana. 7and 8. Kilometer 2 site and Kilometer 4 site-——Two very extensive village sites in the foothills of the mountains southeast of Monte Cristi. Both of these localities differ from those in the Samana Bay region in being situated in the semiarid portion of the island. 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 LIST OF MAMMALS COLLECTED NESOPHONTES PARAMICRUS Miller Railroad cave-—Humerus, I. San Gabriel (owl deposit )—Mandibles, 3; humeri, 4; femora, 6; innominate, I. It is impossible to determine whether or not the presence of the humerus in the Railroad cave kitchenmidden indicates that Neso- phontes was eaten by the Indians. In this cave such a bone might as well have been dropped by an owl as by a man. NESOPHONTES HYPOMICRUS Miller San Gabriel (owl deposit ).—Mandibles, 4; humerus, 1; femur, 1; innominate, I. The remains of both species of Nesophontes agree perfectly in size and other characters with topotypes from St. Michel, Haiti. SOLENODON PARADOXUS Brandt Railroad cave—Perfect right humerus, 1. Naranjo Abajo—Mandible, 1; distal half of left humerus, 1. Rio San Juan.—Mandible, I. Kilometer 2 site—Distal half of humerus, I. These specimens do not differ in any way from the corresponding parts of the living animal. Their presence in three widely separated kitchenmiddens is sufficient indication that Solenodon was customarily eaten by the Indians. EPTESICUS HISPANIOLAE Miller MACROTUS WATERHOUSII WATERHOUSII Gray ARTIBEUS JAMAICENSIS JAMAICENSIS Leach A few remains of these common Dominican bats were found in the owl deposit in San Gabriel cave. CANIS FAMILIARIS Linnaeus Kilometer 2 site——Right mandible, immature, 1; both mandibles of a very young individual, 1 pair; separate milk pm‘, 1; adult m’, 2 (not from same individual); adult canine, 1; adult incisor, 1; auditory bulla, 1; vertebrae, 8; ribs, 2; fragments of pelvis, 4 (repre- senting at least 2 individuals) ; tibia, proximal end, 1; tibia, distal end (probably of another individual), 1; calcanea, 2 (opposites) ; astraga- NO. 5 MAMMALS FROM DOMINICAN REPUBLIC——-MILLER 5 lus, I (apparently belongs with the calcanea) ; metapodials, 9; im- perfect scapula, 1; ulna, 1; radius (perfect) 1; radius (proximal end only), I. The remains pertain to at least two adult dogs and two puppies. Taking the radius (total length 127.6 mm.) scapula, and teeth as guides, the animal must have been about the size of a Scotch terrier whose skeleton is now in the National Museum, No. 21997 (total length of radius 120.2 mm.). I am unable to find characters in any of these specimens that sug- gest specific or racial peculiarities as compared with domestic dogs of European origin or with pre-Columbian dogs from either North or South America. Furthermore, as the middens near Monte Cristi yielded bones of both pig and cow, there is no reason to suppose that the dog had any other than European origin. The apparent absence of dog bones from all the other deposits of Indian refuse is a clear indication that the natives did not habitually use these animals as food. CERCOPITHECUS ? sp. ? Plate 2, fig. 4 Naranjo Abajo.—Distal end of tibia, 1. The well preserved distal end (42 mm.) of a monkey’s tibia was found among the miscellaneous long bones dug from the kitchen- midden on the Naranjo Abajo key. The exact level at which it lay was not determined. In state of preservation the bone is essentially like the rodent leg bones from the same deposit. I cannot identify this fragment with the corresponding part of any American primate, chiefly because the shaft of the bone, im- mediately above the articular enlargement is too robust. By this character the fragment (pl. 2, fig. 4) can at once be distinguished from specimens of Cebus (pl. 2, fig. 6) Ateles, and Alouatta, the only common genera containing species large enough to approach it in size. When compared with Cercopithecus (pl. 2, fig. 5), however, the dis- crepancy is less obvious, though I have not been able to find an African tibia that I should regard as certainly pertaining to the same species. As members of this genus were early introduced into the Lesser Antilles I am inclined to believe that the monkey of the Naranjo Abajo key had been brought over alive before the Indians abandoned the coast of Samana Bay. BROTOMYS VORATUS Miller Plate 1, fig. 3 Railroad cave——Skull, lacking braincase and all teeth except pm*, 1; fragments from interorbital region, 2; mandibles, 7. 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 Boca del Infierno—Humerus, I. San Gabriel (owl deposit ).—Lower incisor, 1; humeri, 3. San Gabriel (culture deposit ).—Mandible, 1. Naranjo Abajo.—Right side of palate with pm* and m! in place, I; mandibles, 3. Anadel.—Mandibles, 14. Rio San Juan.—Right side of palate with all four teeth in place, 1; fragment of premaxilla with incisor in place, 2; mandibles, 43. Kilometer 2 site——Right premaxilla and anterior portion of palate with pm‘ in place, I; palate with all the alveoli and pm* left and pm* and m1? right in place, 1. Left side of palate with alveoli of all four teeth, I ; mandibles, 61. Kilometer 4 site-—Mandibles, 16. The frequency with which the bones of this animal occur in the Indian deposits indicates that Brotomys must have been abundant and generally distributed in pre-Columbian days. It was probably much like the living South American spiny-rats in size and general form, but with heavier, less elongated head. I have little doubt that this animal was the mohuy described by Oviedo as the most eagerly sought for of the native edible quadrupeds (see p. 13). This material agrees in all essential features with the original specimens from San Pedro de Macoris and with those that have been collected in the Haitian cave deposits. Except for individual pecu- liarities that appear to be due to age the jaws are very constant in all their characters. I can detect no differences between those collected in the humid Samana Bay region and those from the semiarid country near Monte Cristi. In one jaw from Kilometer 2 site, the premolar is in a stage of wear to show that the small enamel “lake ” usually present in the anterior lobe of the crown is the remnant of a reentrant fold penetrating from the outer side of the tooth.’ In two others from Rio San Juan, the lake has been joined to the tip of the anterior inner reentrant fold, while in one specimen from the same locality, the crown, though not exces- sively worn, shows no trace of the anterior “lake,” its pattern thus resembling that of the molars. ISOLOBODON PORTORICENSIS Allen Plate 1, fig. 6 Railroad cave —Imperfect skulls, 4; left half of rostrum, 1; right premaxillary with incisor, 1. Left half of palate, without teeth, 1; right half of palate, m? in place, I; mandibles, 20. * An even better specimen in the same stage was collected by Arthur J. Poole in the small cave near St. Michel, Haiti. 4 NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER Hi Boca del Infierno—Imperfect palate with left m* in place, 1; mandibles, 7. San Gabriel (culture deposit).—Palate, 1; fragment of left pre- maxilla with incisor, I ; mandibles, 3. Naranjo Abajo.—FPalate with right m? in place, 1; upper molar of a larger individual, 1; mandibles, 3. Anadel.—Palate with all teeth, 1; fragments of rostrum with in- cisor, 5; occipitals, 1; mandibles, 41. Numerous odd teeth. Rio San Juan.—Broken skull, 1; complete palate with all teeth, 1; palate lacking left m*, 1; fragments of palate, 9; fragments of rostrum with incisor, 10; mandibles, 184. Kilometer 2 site—Imperfect skull, 1; fragments of palate, 3; mandibles, 10. ISOLOBODON LEVIR (Miller) Plate 1, fig. 5 San Gabriel (owl deposit )—Imperfect skulls, 2; palate with right molars in place, 1; separate maxillary teeth, 2; mandibles, 13. Kilometer 2 site——Palates and fragments, 21; mandibles, 281. These specimens agree with the original series from caves near St. Michel, Haiti, and differ obviously from the remains of [solobodon portoricensis recovered from the kitchenmiddens in the Samana region. Among 15 jaws selected for large size, the length of mandible from articular process ranges from 44.6 to 48 mm., height of ascending ramus through articular process from 20.6 to 23 mm., and alveolar length of toothrow from 16 to 17.6 mm. In 11 jaws of J. portoricensis from the San Juan River, also selected for large size, the extremes of the same measurements are respectively 50 to 52.6 mm., 24 to 26.6 mm. and 19 to 20.8 mm. After examining the entire series of Santo Domingan Isolobodon remains I am still as unable to distinguish the large form from the Porto Rican J. portoricensis as I was in 1918 on the basis of the very few specimens then collected. It seems improbable that such a distribution could exist without human intervention. No other species of rodent has been found to be common to the two islands and no species could be expected to remain constant in two areas that have been separated as long as these two land masses. Finally, Porto Rico and the eastern part of the Dominican Republic, together with the Virgin Islands, where the same large Jsolobodon also occurred, are in a region known to have been freely traded over by pre- Columbian man in his sea-going canoes. It must be admitted, however, that the hypothesis of human transportation meets with a difficulty & SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 not easy to dispose of, namely, the fact that no Plagiodontia or Brotomys seems to have been carried in the opposite direction to Porto Rico or the Virgin Islands. At only two localities have the large and small forms of /solobodon thus far been found together, in the kitchenmidden at the Kilometer 2 site near Monte Cristi and in San Gabriel cave. In the kitchenmidden the remains of the two were mingled together—ten jaws of the large animal among a total of 290. In the cave they occurred separately— the large animal in the culture deposit at the main (south) opening, the small one in the owl deposit near the middle of the long, ascending passage that leads up to the aperture facing north. All the bones in the owl deposit have the appearance of much greater age than those in the midden. The material in which they were found is heavily and uniformly impregnated with lime, while that in the midden, like that in the human deposits in all the neighboring caves, shows no such infiltration except at spots where actual drip from the ceiling is now taking place. The presence of Aphetreus montanus among the owl refuse may also be an indication of greater age, as this rodent has not yet been found in any midden, though it is the second most common species in the owl-made cave deposits near St. Michel, Haiti. On the assumption that Jsolobodon portoricensis was introduced by man in the Samana Bay region, these facts would be explained by supposing that the San Gabriel owl deposits were formed before the importation of this larger species and the subsequent extermination of the smaller indigenous form. The process of replacement of the smaller animal by the larger would have afterward become so com- plete throughout the Samana region that no remains of the native species have been found in the deposits left by the Indians. Extending its range westward, Jsolobodon portoricensis would have just begun to establish itself near Monte Cristi when both it and the Indians became extinct. APHATREUS MONTANUS Miller San Gabriel (owl deposit )—Mandibles, 3. These specimens show no peculiarities as compared with jaws from the type locality, near St. Michel, Haiti. No bones of Aphetreus have yet been found in any culture deposit. PLAGIODONTIA ADIUM F. Cuvier Plate 1, fig. 2 Anadel—tImperfect skulls, 2; fragments of palate, 2; mandibles, 20; odd teeth, 9. NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 9 Rio San Juan—Rostrum with incisors and first two cheekteeth, 1; fragments of premaxilla with incisor, I; mandibles, 30; odd teeth, 25. Kilometer 2 site—Fragments of palate, 2; complete mandible, 1; fragments of mandibles, 2; odd teeth, 3. Kilometer 4 site-—Fragment of palate, 1 ; mandibles, 6; odd teeth, 5. PLAGIODONTIA HYLAUM Miller Plate 1, fig. 1 Railroad cave——Imperfect skulls, 2; right side of rostrum with incisor, 1; palate lacking m* of both sides, 1; mandibles, 4. San Gabriel (owl deposit )—Mandible, 1 young; left lower incisor, adit, 2. The specimens now at hand enable me to confirm the original diagnosis of Plagiodontia hyleum and also to add two important characters. That the living animal is decidedly smaller than Plagiodontia edium is abundantly shown by comparison of the skulls and jaws from Guarabo and the south shore of Samana Bay with the remains of the larger animal collected on the Samana peninsula and near Monte Cristi. The 12 jaws of P. hyleum whose measurements are given in the original description range from 51 to 55.2 mm. in length. An additional specimen from the Railroad cave is slightly imperfect but its length must have been about 51 mm. One mandible of P. edium from San Pedro de Macoris was recorded as slightly more than 62 mm. long. Unfortunately most of the jaws from the Samana Peninsula are injured at one end or the other, so that their length cannot be de- termined, but two from Anadel give measurements of approximately 61 and 62 mm. A measurement that is more useful, because mandibles are seldom so badly broken that it cannot be taken, is the depth from the alveolar margin to the protuberance made by the root of pmg. In 10 jaws of Plagiodontia edium this depth averages 16.3 mm. with extremes of 15.4 and 17.4 mm. In an equal number of jaws of the smaller animal the average depth is 13.2 mm., the extremes 12.2 and 14.0 mm. Similarly obvious and constant is the difference between the alveolar length of mandibular toothrow in the two species. Ten specimens of each give the following averages and extremes: P. hyleum, 19.8 mm. (18.6 to 20.6 mm.) ; P. edium, 24.2 mm. (23.2 to 25.4 mm.). The most important character brought to light by the new material is, however, the difference in relative length of the first and second maxillary cheekteeth. In Plagiodontia hyleum the crown length in- 10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 creases gradually and rather uniformly from the fourth tooth to the first; in P. edium there is the same gradual increase from fourth to second, and then an obviously and abruptly greater increase from second to first (see pl. 1, figs. I and 2). The relative lengths of the first and second teeth, measured along the median line of the grinding surface is as follows in seven specimens of each species: P. hyleum, pm‘, average 6.1; m+, average 5.1; ratio of premolar to molar 119.8; P. edium, pm‘, average 7.6; m', average 5.6; ratio of premolar to molar 135.7. CAPROMYS PILORIDES Desmarest Plate 1, fig. 4 San Gabriel (culture deposit).—Complete nasals and turbinates, 1; right mandibles (all toothless), 5; upper incisors, 2. These specimens were found near together in the San Gabriel kitchenmidden at a depth of about three feet. They do not differ from the corresponding parts of Cuban skulls of Capromys pilorides in any way that I can discover. Consequently I have no doubt that the animals to which they pertained were brought to the cave as food, either by the Indians or by early European sailors. QUEMISIA GRAVIS Miller Plate 2, fig. 3 Boca del Infierno—Distal half of right femur, 1; proximal ex- tremity of left ulna, I. Both fragments (pl. 2, fig. 3) were found at a depth of about four feet in the kitchenmidden near the south entrance to the outermost of the two caves. As compared with the corresponding part in the Porto Rican Elasmodontomys the distal extremity of the femur has a reduced antero-posterior diameter (ratio to lateral diameter about 78 instead of 92.5 and 93.6 in two Elasmodontomys) ; the shaft is more flattened on its anterior aspect and less flattened on its posterior aspect; and the antero-posterior diameter at middle of shaft is less in proportion to the transverse diameter. As compared with the femurs of /solobodon and Plagiodontia from the Samana region this fragment is at once distinguishable by its strikingly greater size. It appears to correspond perfectly with the opposite end of the femur of Quemisia that I found in one of the caves near the Atalaye Plantation, St. Michel, Haiti; and its presence No. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER II in a kitchenmidden confirms my belief that this large rodent is Oviedo’s “ quemi.” CAVIA sp. Anadel_—Mandibles, 2 (opposites but not from one individual). I cannot distinguish these jaws from specimens of Cavia porcellus. They present every appearance of having been buried as long as the remains of Brotomys voratus and Plagiodontia edium with which they were associated. ACRATOCNUS COMES Miller ? Plate 2, fig. 2 Boca del Infierno—Penultimate phalangeal bone, probably of sec- ond or fourth pedal digit, 1. This bone was found in the kitchenmidden at the south entrance to the outermost of the two caves. It was unearthed at a depth of not more than four feet, near the femur of Quemisia, with which it agrees in its perfect and seemingly unmodified condition, of preserva- tion. Both bones, in fact, seem to be, so far as it is possible to de- termine from superficial inspection, in essentially the same state as bones of the living species of Plagiodontia with which they were associated. There appears to be no longer the slightest reason to doubt that a ground sloth was a member of the recently man-exter- minated fauna of Hispaniola.’ This bone (pl. 2, fig. 2) is similar in general form to the second right pedal phalanx of the Patagonian Hapalops elongatus as figured by Scott (Rep. Princeton Univ. Exped. Patagonia, Vol. 5, Palaeont, 2, pl. 41, fig. 2), but it is about 2 mm. longer and its proximal extremity appears to be deeper. It also resembles in a general way an isolated phalangeal bone of Acratocnus from Porto Rico figured by Anthony (item: miuer. Mus. Nat. Hist...n'-s. Vol:’2,.Pt 2. fie. 53 f, p. 425, 1918). From an imperfect specimen that may represent the cor- responding bone in Acratocnus comes it differs rather noticeably in the less diameter of the distal articular region (compare pl. 2, figs, 1 and 2) and the more abrupt deepening toward the proximal end. TRICHECHUS MANATUS Linnaeus Rio San Juan—Fragments of palate, 2 (large and small) ; im- perfect ribs, 2. *T have already discussed the evidence to this effect furnished by the conditions existing in the caves near St. Michel, Haiti (Smithsonian Misc. Coll., Vol. 81, No. 9, pp. 25-26, March 30, 1929). 12 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 Kilometer 2 site-——Palate, 1; odd teeth, 8; vertebrae, 2. Kilometer 4 site-—Fragments of occipital region, 2; fragments of mandible, 2; broken ribs, 13; humerus, 1; distal end of humerus, 1; fragment of scapula, 1; fragment of femur, I. These specimens do not differ appreciably from Florida material, except that the alveoli in the palate found at the Kilometer 2 village site appear to be exceptionally large. THE MAMMALS DESCRIBED BY OVIEDO Gonzalo Fernandez de Oviedo y Valdés (1478-1557), the first European chronicler of things West Indian, was alcalde of Santo Domingo City from January, 1536, to August, 1546. In his Historia GENERAL y NATURAL DE Las Inp1As, Book 12, Chapters 1 to 6 (pp. 389-392 of the edition issued by the Royal Academy of History, Madrid, 1851) he described the following mammals as known or believed by him to inhabit the island of Hispaniola: the hutia, the quemi, the mohuy, the cori, the dumb dog (“perro mudo”) and the mice (‘‘mures 6 ratones’’). Hitherto there has been much doubt as to the exact identification of these animals, for the reason that Plagiodontia edium and Soleno- don paradoxus were, up to a few years ago, the only indigenous mammals known, other than bats and sea-cows. It now seems possible, however, to allocate all of Oviedo’s names, with the exception of the “dumb dog.” I shall take them up in order. THE HUTIA Oviedo writes that there occur in this island of Hispaniola, and in others lying in the seas near it, animals called hutia, four-footed, and resembling a rabbit, but smaller sized, smaller eared and rat-tailed. The natives, he says, kill them with small dogs that they have in domestication, dumb and not knowing how to bark; and the Christians do this much better with the dogs they brought from Spain. “ These animals are grizzled gray (pardo gris) in color according to the evidence of many who have seen and eaten them and who praise them as food; and there are now many persons in this city of Santo Domingo and in this island who say so. But at present these animals are no longer found except very rarely.” This account would apply so well to the species of Plagiodontia, and presumably also to the Isolobodons, that there seems to be no reason to doubt that these were the animals that Oviedo had in mind. By the present day Dominicans the name seems to have been trans- NO: 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 13 ferred to Solenodon; at least, such persons whom I met as knew of an animal called hutia expatiated on the great length and pointedness of the creature’s snout. The very few who were acquainted with Plagiodontia hyleum happened to be English speaking descendants of negroes from the United States. They always spoke of the animal as the “muskrat,” and they told me that many of these creatures had been killed by the workmen who cleared the narrow San Lorenzo Peninsula for cocoanut planting 20 or more years ago. THE QUEMI The quemi resembled the hutia in color and general appearance, but was much larger, its size equaling that of a medium-sized hound. Oviedo did not see it himself, and he believed it to be extinct. How- ever, he assures his readers that: “‘ There are many persons in this island and in this city who have seen and eaten these animals and who declare that they were good food; but in truth, according to what has been said and known about the hardships and deprivations that the first colonists endured in this island it can be presumed that everything that could be eaten must have then appeared to them very good and delicious, even when it was not.” The qualifications of an animal resembling the hutia, good to eat, and as big as an ordinary hound seemed to me to be fulfilled by the large rodent whose remains I found in the caves near St. Michel, Haiti, in 1925. Consequently I proposed for it the generic name Quemusia. The presence of the same creature in the Boca del Infierno kitchenmidden appears to confirm my guess. THE MOHUY “The mohuy is an animal somewhat smaller than the hutia: its color is paler and likewise gray. This was the food most valued and esteemed by the caciques and chiefs of this island; and the character of the animal was much like the hutia except that the hair was denser and coarser (or more stiff), and very pointed and standing erect or straight above. I have not seen this animal, but there are many who declared it to be as aforesaid ; and in this island there are many persons who have seen it and eaten it, and who praise this meat as better than all the others we have spoken about.” There can be little if any doubt that the animal Oviedo thus de- scribed was Brotomys voratus. This rodent was smaller than either Plagiodontia hyleum or Isolobodon levir, and its remains have been found in every kitchenmidden that has been examined in the Domini- IA SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 can Republic (the type specimen came from San Pedro de Macoris), a fact that shows how universally it was liked as food. Finally the account of stiff, pointed, erect-standing hairs of the back seems especially applicable to a relative of the South American spiny-rats. THE CORI Oviedo had first-hand knowledge of the cori. Consequently his description of it is more detailed and accurate than in the case of the three preceding animals. He writes: “ The cori is a small quad- ruped, the size of a half grown young rabbit. These coris appear to be a species of the rabbit kind although they have a muzzle like a rat but not so pointed. They have very small ears which they hold so close that it appears as if they lacked them or did not have any. They have no tail whatever ; they are very slender as to feet and hands from the joints or hams downward; they have three fingers and another smaller, and very slender. They are wholly white, and others every- where black, and the most of them spotted with both colors. Also some are wholly reddish and some spotted with reddish and- white.” Continuing his account he says that the coris are kept in the house and fed on grass, with some cassava to fatten them. He has eaten them and found them to taste like young rabbit. When he wrote they were plentiful in Santo Domingo City. They were also to be found on other islands and on the mainland. It is not difficult to recognize the guineapig in this account of the cori; but if any doubts might have existed, in the absence of more tangible evidence, they are disposed of by Mr. Krieger’s discovery of the two Cavia jaws in the kitchenmidden at Anadel. It remains an open question whether the guineapig was introduced by the Span- iards or by native trade with South America. I incline to the first alternative, chiefly because remains of the animal have been found in only one midden. Bones of cow, horse, and pig, as well as artifacts of European origin occasionally occur in the Indian deposits, showing that the native village sites continued to be used for some time after the Spanish conquest began, and that material brought in by the newcomers found its way to the aboriginal refuse heaps. Such might easily have been the history of the guineapig jaws at Anadel. THE DUMB DOG In his account of the hutia we found Oviedo alluding to a native dog that could not bark, but which was, nevertheless, very useful as a game getter. On pages 390-391 of the 1851 edition of his book NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER I5 he gives an extended account of the dogs formerly and at the time of his residence (1536-1546) occurring on the island of Hispaniola. Parts of this account I translate as follows: “ Domestic cur dogs were found in this island of Hispaniola and in all the other islands of these seas (inhabited by Christians). They were bred by the Indians in their houses. At present there are none; but when they had them the Indians used them to capture all the other animals [that is, the hutia, the quemi, the mohuy and the cori] that have been spoken of in the preceding sections. These dogs were of all the colors that dogs have in Spain ; some of a single color and others spotted with white and blackish or reddish or ruddy or any color that the coat is accustomed to have in Castile. Some woolly, others silky, others short-haired ; but the most of them between silky and short-haired, and the hair of all of them more harsh than our dogs have, and the ears lively and alert like those of wolves. All of these dogs, here in this island and the other islands, were mute, and even though they might be beaten and killed they did not know how to bark: some of them yelped or whined when they were hurt.” Continuing, he tells us that he has seen dogs of the same kind on the mainland in the province of Santa Marta as well as in Nicaragua, and that in the latter country the natives regularly used them as food. He makes no mention of the eating of dogs by the natives of Hispaniola, and the complete absence of bones of this animal from the collections made by us in the Samana region and by Theodoor de Booy at San Pedro de Macoris makes it seem probably that this habit did not exist, or at least that it was not very general. If the dumb dog was anything else than a special breed of Canis familiaris we have as yet no evidence of the fact. The five animals thus described are, Oviedo insists (p. 391), the only furred terrestrial quadrupeds, other than rats or mice, native to Hispaniola. It therefore seems evident that he knew nothing about Solenodon or the ground sloth. With regard to the mice, which he believed to be indigenous, there is no reason to suppose that they were not brought over by the Spaniards themselves. No native mammal the size of a mouse, except Nesophontes, has been found in any owl deposit or kitchenmidden on the island, and it seems improbable to the highest degree that this small insectivore could have been the animal known to Oviedo and supposed by him to have been spontaneously generated from some kind of corruption in this remote part of the world. 16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 EXPLANATION OF PLATES PLATE I All figures natural size Fic. 1. Plagiodontia hyleum Miller. Adult male. No. 239801, U. S. Nat. Mus. The largest specimen of the living animal collected by Dr. W. L. Abbott. Guarabo, Dominican Republic, Nov. 24, 1923. Fic. ta. Plagiodontia hyleum Miller. Adult female. No. 239888, U. S. Nat. Mus. Guarabo, Nov. 23, 1923. Fic. 2. Plagiodontia edium Desmarest. Adult. No. 254376, U. S. Nat. Mus. Anadel, Dominican Republic. Fics. 3 and 3a. Brotomys voratus Miller. Nos. 254683 and 254684, U. S. Nat. Mus. Railroad cave, San Lorenzo Bay, Dominican Republic. Fic. 4. Capromys pilorides Desmarest. Adult. No. 254449, U. S. Nat. Mus. San Gabriel cave, Samana Bay, Dominican Republic. (Observe spacing of ridges in alveoli as compared with that of the ridges in alveoli of Jsolobodon, fig. 6.) Fic. 5. Isolobodon levir (Miller). Adult. No. 254686, U. S. Nat. Mus. Near Monte Cristi, Dominican Republic. Fic. 6. Isolobodon portoricensis Allen. Adult. Railroad cave, San Lorenzo Bay, Dominican Republic. PLATE 2 All figures natural size Fic. 1. Acratocnus comes Miller. Phalangeal bone from cave near St. Michel, Haiti. No. 253210, U. S. Nat. Mus. Fic. 2. Acratocnus comes Miller ? Phalangeal bone from kitchenmidden in Boca del Infierno cave, Samana Bay, Dominican Republic. No. 254680, U. S. Nat. Mus. Fic. 3. Quemisia gravis Miller. Parts of femur and ulna from kitchenmidden in Boca del Infierno cave, Samana Bay, Dominican Republic. No. 254681, U. S. Nat. Mus. Fic. 4. Monkey. Lower end of tibia from kitchenmidden on Naranjo Abajo Key, Samana Bay, Dominican Republic. No. 254682, U. S. Nat. Mus. Fic. 5. Cercopithecus pygerythrus. Lower end of tibia. Changamwe, British East Africa. No. 163327, U. S. Nat. Mus. Fic. 6. Cebus capucinus. Lower end of tibia. North Ecuador. No. 113418, U. S. Nat. Mus. =? eae. eee ee ee ee ee Ee ——— ———e——— ss. lhc ee ee SMITHSONIAN MISCELLANEOUS COLLECTIONS VOEMS2 NOs Si rled 1. Plagiodontia hyleeum. 2. Plagiodontia zedium. 3. Brotomys voratus. . Capromys pilorides. . Isolobodon levir. . Isolobodon portoricensis. one > Co (All figures natural size.) SMITHSONIAN MISCELLANEOUS COLLECTIONS Who 25 INOs Be FIL, 2 uu ; es 5 Fa Ta 1. Acratocnus comes. 4. Monkey (not identified ). 2. Acratocnus comes ? 5. Cercopithecus pygerythrus. 3. Quemisia gravis. 6. Cebus capucinus. (.\ll figures natural size.) SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 6 THE PAST CLIMATE OF THE NORTH POLAR REGION BY é EDWARD W. BERRY The Johns Hopkins University (PUBLICATION 3061) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION APRIL 9, 1930 The Lord Baltimore Press BALTIMORE, MD., U. 8. A. A OL am. | a JA ee ak PASI CEivVAtTE OF THE NORTH POLAR REGION * By EDWARD W. BERRY THE JOHNS HOPKINS UNIVERSITY The plants, coal beds, hairy mammoth and woolly rhinoceros; the corals, ammonites and the host of other marine organisms, chiefly invertebrate but including ichthyosaurs and other saurians, that have been discovered beneath the snow and ice of boreal lands have always made a most powerful appeal to the imagination of explorers and geologists. We forget entirely the modern whales, reindeer, musk ox, polar bear, and abundant Arctic marine life, and remember only the seemingly great contrast between the present and this subjective past. Nowhere on the earth is there such an apparent contrast between the present and geologic climates as in the polar regions and’ the mental pictures which have been aroused and the theories by means of which it has been sought to explain the fancied conditions of the past are all, at least in large part, highly imaginary. Occasionally a student like Nathorst (1911) has refused to be carried away by his imagination and has called to mind the mar- velously rich life of the present day Arctic seas, but for the most part those who have speculated on former climates have entirely ignored the results of Arctic oceanography. Recently, Kirk * has mar- shalled some of the evidence of the abundance of the present marine life in the Arctic, and he concludes from this survey that marine organisms are not dependable as indicators of geologic climates. | think this conclusion is impregnable, and therefore if we are ever to get any information regarding past climates, the evidence will be fur- nished by fossil plants, and not too precisely either. Here again prudence is the watchword ; imagination must be entirely suppressed, and the distribution of recent plants must be understood and used. A correct solution of the problem is not only of prime interest to geologists and paleontologists but it offers assurance to geophysicists confronted with the now fashionable belief in wandering poles, and "Given in summary before the Paleontological Society at the December, 1928,. meeting. * Kirk, Edwin, Fossil marine faunas as indicators of climatic conditions. Ann. Rep. Smithsonian Inst. for 1927, pp. 299-307, 1928. SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 6 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 likewise comfort to meteorologists confronted with the traditional view of a lack of climatic zones during most of the eons of earth history. I propose to pass in review what we know of the past dis- tribution of plants in the Arctic, after which I will endeavor to evaluate what they mean in terms of climate. Aside from some very scrappy plant fragments from the Silurian of Norway, the oldest traces of land plants in the north occur in rocks of Devonian age. Devonian plants have been discovered within the Arctic Circle at the three localities shown on the accompanying map, (fig. 1). These range froma few scraps, such as those found in Ellesmere Land and Spitzbergen, to the extensive flora found on Bear Island which embraces 31 named forms. These three floras are of upper Devonian age but not necessarily synchronous, since an earlier and a later horizon is represented on Bear Island and probably on Spitzbergen. I have shown on the map (fig. 1) the occurrence of some other Devonian floras outside the Arctic Circle and some in lower latitudes in order to give an idea of the known geographical range of Devonian plants in the present North Temperate Zone. The oldest of these is the Lower Devonian flora of Roragen, Norway, embracing eight very interesting forms. Of particular interest are the Middle Devonian plants found in silicified peats at Rhynie in northern Scotland and the flora described recently from Germany, since these give us our first considerable insight into the structure of these ancient plants. In looking over the list of identifications from Bear Island, all except Pseudobornia are seen to belong to widely distributed types, several are identical with species from the south of Ireland, and similar forms occur rather generally in lower latitudes. There are several seams of coal at both the older and younger horizons, to which Bothrodendron contributed a large amount of material. Beneath the coal seams are underclays with roots in place and the plant remains show no sorting—that is, delicate material is mixed with stems and branches of all sizes—both facts indicating conclusively that the bulk of the material was not transported but grew in the immediate vicinity. The same statement is true of the Devonian of Ellesmere Land. The plants of the Devonian are so remote from living forms that I do not feel that any conclusions regarding the climate are warranted beyond the statement that they show that there were no climatic barriers to prevent most of the types found in Latitude 45° to 50° extending northward to Latitude 75°. There are, however, certain types which have not yet been found in the north, such as Eosper- — No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 3 SCALE FOR AREA 100.000 SQUARE MILES LAMBERTS AZIMUTHAL, EQUAL AREA PROVECTION, For clase use in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode Published by The University of Chicago Press, Chicago, Ill Copyright 1920, by the University of Chicago Fic. 1—Location of Devonian and Lower Carboniferous northern floras. Melville Island. Devonian Ellesmere Land. Devonian New Brunswick, Maine, etc. Devonian Northeast Greenland. Lower Carboniferous Spitzbergen. Devonian and Lower Carboniferous Bear Island. Devonian and Lower Carboniferous West Norway. Devonian Rhynie, etc. Scotland. Devonian Nova Zembla. Lower Carboniferous Northern Urals. Lower Carboniferous . Siberia. Devonian. SO RIANA Y NO Leal | 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 matopteris from New York and Cladoxylon and Aneurophyton from Germany, that may possibly indicate more genial climates in those places than obtained farther north, and Pseudobornia seems to be a northern type, but until Devonian floras become much better known no adequate conclusions can be reached. There are one or two points that deserve emphasis in this connection. These northern Devonian floras all consist of plants belonging to the Pteridophyte, Arthrophyte, Psilophyte, Lepidophyte and Pteridosperm phyla, and such existing representatives of these phyla as have sur- vived to the present, though few and not directly filiated, such as Equisetum and Lycopodium, are singularly unaffected by temperature. For example, there are now two species of Equisetum and one of Lycopodium found within 10 degrees of the pole in northwestern Greenland (Ostenfeld, 1925). To be sure these modern Greenland forms do not reach the size of their Devonian relatives, but this is true of all existing members of these genera irrespective of latitude. Moreover, all of these northern Devonian plants appear to have been bog types. This conclusion is indicated by their forming coal in place and by the structures disclosed in the silicified peats of Rhynie. Therefore, we conclude that the chief climatic factor was moisture rather than temperature. The fact that many of the Devonian plants were palustrine also gives force to an observation which I have elaborated in another place * that these Devonian plants while ancient and simple were not primitive and ancestral, but were the reduced descendants of more highly organized ancestors. Since speculation was to have no part in this discussion I refrain from elaborating my own belief regarding the more precise character of Devonian climate. LOWER CARBONIFEROUS (DINANTIAN oR CULM) Fossil plants have been found in the Lower Carboniferous, or Mississippian as Americans prefer to call it, at five or six localities within or near the Arctic Circle. These floras range in extent from a few doubtful specimens at some localities to the 59 nominal species described by Nathorst from Spitzbergen. The latter extend to 79° North Latitude, and a considerable flora of similar species to the number of ten at least is found between 80° and 81° North Latitude in northeast Greenland. 1 Berry, Edward W., Devonian Floras. Amer. Journ. Sci., Vol. 14, pp. 109-120, 1927. No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 5 The Spitzbergen flora comprises 12 fernlike plants, 5 pteridosperms, I arthrophyte, 25 lepidophytes, 1 cordaites (wood), and 15 of un- certain botanical affinities. Stigmarias and various roots occur in place beneath the coal seams, showing that the vegetation was pre- served essentially in place; and Lepidodendron stems have been col- lected up to 16 inches in diameter. There are no peculiar Arctic types in this most extensive known Culm flora nor are there any genera that are not common to floras of the same age from lower latitudes. The single wood, Dado. ylon spetsbergense Gothan, fails to disclose any seasonal growth changes, which might be expected to result from the Arctic night. No other traces of the Cordaitales other than this wood have been discovered here, which leads Nathorst to suggest that the wood may have been carried by currents from some more southern clime, where also the woods fail to show growth rings. This may be true, but on the other hand there is great specific varia- tion in the degree to which growth rings develop in existing conifers, as Antevs has pointed out, and they tend to be absent under fairly uniform conditions of humidity. That this is an individual trait of this particular species and is probably without climatic significance is shown by the presence or absence of rings in Devonian and Mississip- pian Dadoxylon woods from lower latitudes. For example, Dadoxylon beinertianum Endlicher from Silesia, Dadoxylon Tchichatche fianium Endlicher from Russia, and Dadoxylon vogesiacum Unger from the Vosges, all of the same age as the Spitzbergen species, show distinct seasonal rings, but other contemporaneous European species fail to show them. I cannot see any very conclusive indications of climate in these Lower Carboniferqus floras, other than the fact that they extended in places to within 10 degrees of the pole. Palustrine types pre- dominate as in the case of the Devonian, and more than half the known forms are Lepidophytes which we have reason to believe show little response to temperature. Sphenophyllums are entirely wanting in Spitzbergen, but are found farther north in Greenland and occur on Bear Island, so that their absence in Spitzbergen is merely an accident of preservation or discovery. In general Arthrophytes are much rarer in the far north than in middle latitudes at this time and the same seems to be true of a number of genera of large fronded fern-like plants, which is taken to indicate differences due to latitude. ERIASSIC Triassic plants except in the latest or Rhaetic stage are scarcely, if at all known in the north polar region. There is a species of 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 Schizoneura recorded from the New Siberian Islands which may be Rhaetic and there are scattered Rhaetic plants in Greenland and Spitzbergen; and somewhat farther south in northwestern Norway (Ando) and southern Sweden. The most extensive northern Rhaetic flora is that from Scoresby Sound, East Greenland, between 70° and 71° North Latitude. This comprises 51 named forms and several additional ones which are not named. Cycads and ferns predominate, and so far as we can judge at this lapse of time all belong to cosmopolitan Rhaetic types. Harris, who has given an excellent account of these plants concludes that they indicate a temperate climate, largely on the ground of the pre- dominance of certain forms indicative of relatively pure stands and the absence of mixtures such as occur in recent tropical assemblages. He concludes also, from a study of the cuticles of many of the species, that moisture was plentiful. The wood of Dadoxylon in the Rhaetic of Spitzbergen has very feebly marked seasonal rings. JURASSIC Supposed Jurassic floras completely surround the pole and are extensively developed throughout Siberia, in Alaska, Greenland, Spitz- bergen, Franz Josef Land, New Siberian Islands, and elsewhere. Formerly, many of these, as those in Siberia, were considered Middle Jurassic, but Nathorst is the authority for the statement that all of the more northern ones are post Oxfordian, and several, such as that of Spitzbergen, are on the border between the Jurassic and the Lower Cretaceous. The Spitzbergen flora is the most extensive and, according to Nathorst, includes 2 horizons, one Portlandian and the other possibly as young as Neocomian. A combined list of these comprises 57 species, including 11 fern-like plants, 1 lepidophyte (Lycopodites), 1 arthrophyte (Equisetites), 4 cycadophytes, 4 Ginkgoales, 23 conifers and 13 of uncertain affinities. Nine different types of coniferous woods have been described and all show pronounced seasonal growth rings. Most of the generic types have a very great geographical range, but several, such as Phoenicopsis, Torellia and Drepanolepis, appear to be distinctly northern, and the predominance of conifers suggests a cool temperate climate. They are found in sandstones associated with coal seams and freshwater mollusks (Lioplax, Unio) and evi- dently grew in the vicinity of their burial place. No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 7 SCALE FOR AREA 100.000 SQUARE MILES LAMBERT'S AZIMUTHAL, EQUAL AREA PROJECTION For class use in Geography, History, Givica, Economics, etc. ‘ Prepared by J. Paul Goode. Published by The University of Chicago Press, Chicago, Ill. Copynght 1920. by the University of Chicago Fic. 2.—Location of Triassic and Jurassic northern floras. 1. Manchuria. Triassic and Jurassic 14. Solitude Island. Jurassic 2. Ussuri. Jurassic 15. Franz Josef Land. Jurassic 3. Amur. Jurassic 16. King Charles Land. Jurassic 4. Trans Baikal. Jurassic 17. Spitzbergen. Triassic and Jurassic 5. Irkutsk, etc. Jurassic 18. Northeast Greenland. Jurassic 6-10. Alaska. Jurassic (?)} 19. East Greenland. Jurassic 11. Bathursy Island. Jurassic 20. Scoresby Sound. Triassic 12. New Siberian Islands. Triassic (?) 21. Ando, Norway. Triassic and Jurassic 22. Scania. Triassic and Jurassic 13. Mouth of Lena. Jurassic 23. Scotland. Triassic and Jurassic. 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 LOWER CRETACEOUS Lower Cretaceous floras are found along the east coast of Asia, in Alaska, Greenland, and King Charles Land. From the last a number of coniferous woods have been described by Gothan. These show pronounced growth rings, said to be more prominent than in woods of the same age from central Europe. Nathorst records an incomplete trunk 32 inches in diameter and showing 210 seasonal rings. The most extensive Arctic flora of Lower Cretaceous age is that described by Heer from the Kome beds of western Greenland, but this, although generally considered to be of Barremian age, is subject to doubt as to age and content because collectors appear to have mixed several Cretaceous horizons. As it stands in the literature it comprises over 100 species, including 46 ferns (no less than 15 are referred to Gleichenia, and although these surely represent that genus they are artificially multiplied), 1 marsilea, 1 lycopod, 3 equise- tums, 13 cycads, 20 conifers, 2 ginkgos, 5 monocotyledons, 3 or 4 dicotyledons, and 6 of uncertain identity. The abundance of ferns indicates a humid climate as does the presence of coal. This flora differs very little from those of corresponding age in lower latitudes (e. g., the Kootenai of western Canada and Montana). UPPER CRETACEOUS Strictly Arctic Upper Cretaceous floras are limited to Alaska and Greenland but others of this age are found in northern Europe and eastern Asia. The most extensive is that from the two horizons in West Greenland known as the Atane and Patoot beds. These have in large part been described by Heer and there is a great and un- warranted multiplication of species. That from the Atane beds has 184 recorded species. It includes 31 ferns, I equisetum, I selaginella, I marsilea, 12 cycads, 2 ginkgos, 25 conifers, 4 monocotyledons, 94 dicotyledons and 14 of uncertain affinities. The seemingly most incompatible plant is the authentically deter- mined Artocarpus and this raises a question which cannot be decided without prejudice. If a genus which is tropical at the present time is found fossil associated with a preponderatingly temperate flora, which is to be given the most weight? The one or the many, bearing in mind the latitude where they occur? My own feeling is that the majority are less likely to have altered their environmental require- ments than the minority, but this falls short of actual proof. The Patoot flora includes 19 ferns, I equisetum, 19 conifers, 2 monocotyledons, 80 dicotyledons, and 2 uncertain. NO. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 9 SCALE FOR AREA 100.000 SQUARE MILES LAMBERT'S AZIMUTHAL EQUAL AREA PROJECTION For clase use in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode. Published by The University of Chicago Press, Chicago, Ill. Copyright 1920, by the University of Chicago Fic. 3.—Location of Cretaceous northern floras. 1. Japan tr. Vancouver Island 2. Sakhalin Island 12. Kootenai - 3-4. Siberia 13. Mattagami, Ontario 5. Klin 14. West Greenland (Kome, Atane, 6-8. Alaska Patoot) 9. Spitzbergen 15. Scania 10. Queen Charlotte Islands 16. Wealden. 10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 TERTIARY Tertiary plants from the Arctic have been encountered at very many localities, usually associated with coal. This, and plants with their roots in place as in the case of Equisetum in Spitzbergen; the association with fresh water mollusks, as in Greenland; or aquatic beetles, as in Spitzbergen and Iceland; as also the presence of fresh water diatoms in the matrix and the mixtures of branches and delicate foliage, prove conclusively that these Arctic floras and the associated coals cannot represent drift material from lower latitudes as some have supposed.’ The similarity in facies and their mode of occurrence, as well as the similar petrographic character of the intimately associated basalts suggest that all of these Tertiary Arctic floras are essentially similar in age, although it is clear that in Spitzbergen, Alaska and probably elsewhere, more than a single horizon is represented. Heer, the pioneer in this field, called them Miocene, just as Lesquereux called the Fort Union and Wilcox floras Miocene, but the Arctic Ter- tiary floras are certainly older than Miocene and younger than Ft. Union. This is indicated by the determination of the so-called Kenai flora of Alaska as of upper Eocene age, and if any one of them 1s proved to be upper Eocene none of the others can be older than middle Eocene or younger than Oligocene. Collateral evidence of their age is furnished by the age of the greatest extension of subtropical floras into the Temperate Zone, which is in upper Eocene ( Jackson) to middle Oligocene (Vicksburg) time. Plants or coal of Tertiary age are found at the numerous widely distributed localities shown on the accompanying sketch map (fig. 4). These completely encircle the pole and reach to within 85° of it (Grinnell Land). These will be treated at greater length than the older floras because in some cases they are more extensive and also because they consist very largely of species belonging to existing genera, and hence can be discussed more intelligently than the older floras. It may be well at the start to dispose of an oft quoted assertion, as for instance “most of Heer’s determinations were based upon leaves, which give no data for generic identification’ (Gregory, op. cit., p. 413). I would readily admit that much of Heer’s material was fragmentary, that he was over sanguine in some of his determinations, * Gregory makes much of this idea, which as we have seen is easily disproved. Gregory, J. W., Congres Géol. Intern. Compte rendu Xéme Session Mexico, 1906, p. 413, 1907. NO. O PAST CLIMATE OF NORTH POLAR REGION—BERRY [I SCALE FOR AREA 100,000 SQUARE MILES LAMBERT AZIMUTHAL FQUAL AREA PROJECTION For class use in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode. Published by The University of Chicago Presa, Chicago, Ill. Copyright 1920, by the University of Chicago Fic.4.—Location of Tertiary northern floras. 1. Commander Islands 21. Prince Patrick Island 2. Japan 22. Melville Island 3. Sakhalin Island 23. Bathurst Island 4-8. Eastern Siberia 24. North Devon g-11. Northern Siberia 25-26. Ellesmere Land 12. Central Siberia 27-28. West Greenland 13. Vancouver Island 29. New Siberian Islands 14. British Columbia 30. Nova Zembla 15-18. Kenai 31. Spitzbergen 19. Mouth of the Mackenzie 32. Iceland 20. Banks Land 33. North Ireland and Mull. TZ SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 and described a great many more species than he should have done. Some genera do not have a characteristic leaf form, but to make such a statement of genera such as Liquidambar, Betula, Corylus, Ulmus, Platanus, Sassafras, Liriodendron, Acer, Potamogeton, Cornus, and Nymphza, to mention but a few of those recorded from the Arctic Tertiary, is the height of misunderstanding. Moreover, as I pointed out in 1922 (op. cit., p. 4): “ Plant fossils have this merit aside from any question of botanical identification, and this feature seems to have been lost sight of by numerous critics of paleobotanical practise: that the size and form of leaves, their texture, the arrangement and character of their stomata, and the seasonal changes in wood, afford criteria that are quite as valuable climatically even though the species or genus to which they belong remains undetermined.” Furthermore, a great many of the generic determinations are corroborated by fruits and seeds, as for example, the genera Vitis, Acer, Nyssa, Hicoria, Juglans, Liriodendron, Fraxinus, etc. As recorded in the literature the number of species varies from the single Pinus recorded from Bathurst Island, 5 species from Elles- mere Land, 6 species from Banks Land to 55 species from Iceland, 168 species from Spitzbergen, and 283 species from Greenland, the last being greatly overelaborated. I have shown * that Heer’s 30 species of fossil plants from Grinnell Land (Lat. 81° 42’) represent not more than half that number; and that Viburnum, Alnus, Ulmus and Tilia represent Populus and Corylus. As thus revised the Grinnell Flora contains nothing extraordinary unless it be the supposed Nymphzea rootstock and this may really belong to one of the plants represented by fragments of grasses or sedges. I will consider only the four most extensive of these floras in any detail. These are Iceland, Spitzbergen, Greenland and Alaska. The Icelandic flora is preserved in tuffs, along with fresh-water diatoms, Unios, Potamogeton; and the wood and branches appear to have been broken off and buried by showers of ashes. The woods show sharply marked seasonal rings; and conifers, willows, alders, birch, and hazel are prominent. The only plants certainly determined that might not justly be considered cool temperate are the following: Platanus, Liriodendron, Acer, Juglans, Ginkgo, Fraxinus, Hicoria. Representatives of all of these except Ginkgo, which is not a native, and Liriodendron, which reaches its northern limit in southern New England, are hardy in northern New England (Platanus) or eastern Canada (Acer, Juglans, Hicoria, Fraxinus) at the present time. 1 Berry, Edward W., Proc. Amer. Phil. Soc., Vol. 61, pp. 8-9, 1922. NO. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY I ios) The Spitzbergen flora comes from two horizons and the two total 108 species and are not essentially different in facies. They are as- sociated with coal seams and are clearly continental palustrine associa- tions. There are 4 ferns, a Ginkgo, 27 conifers, 27 monocotyledons and 80 dicotyledons. Three woods described by Gothan show marked seasonal rings. The warmer elements are Taxodium, Platanus, Jug- lans, Nymphza, Magnolia and Nyssa. Here also oaks, hazels, willows, poplars and conifers predominate. There is not a single tropical or subtropical type and not one justly considered warm temperate. The Greenland Tertiary flora comprises 283 nominal species and includes 8 fungi, 1 moss, 1 lycopod, 1 equisetum, 19 ferns (all tem- perate types), 1 Ginkgo, 28 conifers, 21 monocotyledons and 202 dicotyledons. The petrified coniferous woods show well marked seasonal rings and the only genus that is seemingly out of place in the far north is Taxodium, whose abundance in all Arctic floras and in proved temperate floras of other regions and other horizons shows that it was not out of place here. The monocotyledons include mostly miscellaneous leaf fragments, not generically determinable, as well as two supposed palms (Flabellaria). It has frequently been pointed out by others as well as by myself that the nature of the last cannot be considered as proving the presence of palms. The dicotyledons are very much overelaborated. Probably 100 species is nearer the correct figure than the 202 which Heer differentiated. In Greenland as in all known Tertiary Arctic floras the leaves of willows, poplars, birches, and hazels predominate, but there are many other genera whose identification cannot be disputed, such as Liquid- ambar, Alnus, Fagus, Quercus, Ulmus, Platanus, Sassafras, Fraxinus, Cornus, Liriodendron, Acer, etc. Vitis is represented by both leaves and seeds, and other genera also show fruits. The genera that appear to me to be highly questionable are the following: Castanea, Juglans, Pterocarya, Benzoin, Laurus, Myrsine, Apeiobopsis, Pterospermites, Zizyphus, Colutea, Dalbergia, Diospyros, Sapindus, and several others. I base this conclusion on the fossils and not on the probabilities of their presence. Some, such as Zizyphus and Ficus clearly do not represent those genera, in fact Heer’s discussion shows his lack of conviction of the latter and he queried his determination. Heer devoted considerable space to a discussion of the climatic significance of this as well as other Arctic floras and concluded that the Greenland plants indicated a mean annual temperature of 53.6° F., or a considerably lower figure than he estimated by the same methods for the supposed contemporaneous flora of Switzerland, thus clearly recognizing a climatic zonation. 14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8&2 The so-called Kenai flora of Alaska was originally described by Heer and additions to it have been published by Lesquereux and Knowlton. Hollick has been engaged in a revision of this and related floras from Alaska for a number of years, but his results are not yet published. That from the type locality as listed by Hollick in 1915 comprised but 40 named species and contains not a single tropical or subtropical type. Associated with the plants are thick coal seams and fresh water mollusca (Unio, Anadon, Amicola, Mel- ania), as well as beetle elytra. He states in a recent letter that localities in the southeastern coastal region of Alaska (Alexander Archipelago) have yielded a Tertiary flora that is distinctly indicative of warmer climatic conditions than those from farther north, including cycads, palms, and such dicoty- ledonous genera as Anona, Dillenia, etc., but he has not yet determined whether they are the same or different in age. In either case they sup- port the conclusion that climatic zoning is indicated. As listed by Knowlton* in 1919 the Kenai flora (so called) comprised about 120 species. The most abundant forms are willows, oaks, poplars, walnuts, beeches, birches, hazels, and alders—dis- tinctly temperate, and cool rather than warm temperate types. Per- haps the most abundant plants individually, certainly the widest rang- ing geographically in northern latitudes (Holarctica), are the leaves of hazel bushes (Corylus). Of the 54 genera of Knowlton’s list, the following nine are not present in the existing flora of North America: Ginkgo, Glyptostrobus, Taxites, Hedera, Paliurus, Elaeodendron, Pterospermites, Trapa, and Zizyphus, It may seem that I am juggling the evidence in omitting these nine genera from further consideration, but let me point out that the three of these about which there seems to be no doubt regarding their iden- tity, namely, Ginkgo, Trapa, and Glyptostrobus, are all temperate types in the existing flora. The remaining six genera are under more or less suspicion of quite a different order from any differences of opinion among paleobotanists regarding the identification of the hazels, birches, alders, etc., with which they are associated. Opinion might differ as to whether a particular species of the latter was a Betula or Alnus, an Ulmus or a Carpinus, or a Planera; or whether one or several species of Corylus should be recognized as distinct species ; but opinion is unanimous that the choice is thus narrowed, whereas in the case of such things as Tavites—all any one knows is that it represents * Hollick, A., U. S. Geol. Surv. Bull. 587, pp. 88-89, 19015. * Knowlton, F. H., U. S. Geol. Surv. Bull. 696, pp. 786-780, 1910. No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY I5 some Conifer. Why waste time trying to explain the climatic signifi- cance of Paliurus, a mostly extinct genus, when the particular fossil is probably not a Paliurus; or why concern oneself with an Arctic species of Zizyphus when the form in question is probably a Ceano- thus? I ask, can any one prove that the form-genus Pterospermites is genetically related to the existing genus Pterospermum? or that Elaeodendron is a sound botanical identification? I think not! On the other hand, the great mass of not only the Kenai but of all the Arctic Tertiary floras are the readily recognizable, normal units of a natural assemblage, which individually leave but slight room for dif- ferences of opinion regarding their identity. If fruits chance to be found in association with the leaves, they are such things as birch or alder cones, never the fruits of the “suspects” above mentioned. Of the remaining genera listed in the Kenai flora, all but the follow- ing six are represented in the existing flora of Canada: A¢sculus, Diospyros, Ficus, Liquidambar, Sequoia, and Taxodium. It may be said of these that the #sculus may not be an Zsculus, but a Hicoria; that the two species that have been referred to Ficus do not belong in that genus; and that Sequoia is on the verge of extinction at the present time and its modern range bears little relation to its former range. The case of Sequoia is of especial interest in its bearing on my thesis. Formerly a Holarctic type, it survives today in a most re- stricted area particularly favored by humidity. The remaining genera of the Kenai flora appear to be determined with reasonable certainty. Not only are 39 of these represented in the existing flora of Canada, but the following are still represented in the existing flora of Alaska, or adjacent areas in northwestern Canada, or as far north as Labrador and Hudson Bay in eastern Canada: Abies, Acer, Alnus, Alnites, Andromeda, Betula, Carex, Corylus, Equisetum, Fraxinus, Myrica, Osmunda, Phragmites (grass), Picea, Pinus, Populus, Prunus, Pteris, Quercus, Sagittaria, Salix, Spiraea, Thuites, and Vaccinium. Seventeen of the Kenai species are conifers, and the only types that would seemingly be out of place in a cool temperate climate with well-distributed moisture are Liquidambar, Paliurus, Taxodium, and Zizyphus. I have already given reasons for discrediting the deter- minations of some of these, and all of them have frequently been found fossil in temperate assemblages. The significant feature about these Eocene Arctic floras is that they show a comparable northward swing of not alone their northern limits, but also of their southern limits, which in turn is comparable to the northward advance of the Jackson flora that I have considered 16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 to be of the same age. The Jackson flora reaches Latitude 37° North. The most similar existing flora to that of the Jackson does not extend above Latitude 26° North, and then only under especially favorable conditions of situation with respect to warm ocean currents. This is a difference of 11 degrees. The flora of the Jackson was, moreover, a coastal flora, and I have not the slightest doubt but that had the Mississippi embayment extended five degrees farther North, its shores would have been clothed with the same Jackson flora, for at that time similar floras are found in the Paris Basin in Latitude 49° North, in southern England in Latitude 51° North, and along the expanded Mediterranean sea of the Old World. ; The southern limit of the contemporaneous “ Arctic flora” is about Latitude 45° North in North America (British Columbia), and about 57. North in Europe (Isle of Mull). It seems to me that the essential concordance of these facts is significant, and whatever may be thought of them, it would certainly seem to be difficult for any one to claim that these various Eocene floras mentioned do not show a climatic change in passing northward from the equator toward the pole. Moreover, at present—a time of, in many ways, an abnormal climate in a geologic sense; with rather sharp zoning, although not nearly so sharp as the textbooks would have us believe; a time of almost, if not quite, un- precedented land expansion in the Northern Hemisphere, which I believe expresses a casual relationship—the reliable members of these IXocene Arctic floras range much farther southward than they did in late Eocene time. EXISTING ARCTIC FLORAS Greenland is the most illuminating of Arctic Lands because it is much the largest, and therefore more likely to preserve endemic species, and to receive immigrants from other Holarctic lands. Al- though mostly covered by ice which rises to an altitude of more than 8,000 feet in the interior, it has island peaks (nunataks) with recent plants. Moreover the northeastern part appears never to have been glaciated. About 400 species of recent vascular plants have been recorded from Greenland and at the south trees may reach heights of 10 or 12 feet. North of the Arctic Circle the number of plants is fewer, but Ostenfeld (1925) records 125 species north of Latitude 76° and 108 between Latitudes 78° and 80°, including 2 equisetums, a lycopod, 3 ferns, 32 monocotys and 70 dicotys, including Salix and Vaccinium. In an earlier paper (Ostenfeld, 1923) this author describes the flora of the north coast and records 70 species of plants from Latitude 82°. NO. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 17 This brief statement will be sufficient to indicate that there are other and more important factors than cold. The almost entire absence of vascular plants (a single species as I recall it) from Antarctica shows the part geography plays in the problem. The absence of trees in Lapland (Kihlman) shows the part taken by cold desiccating winds. The northern limits of many tree species in coastal Alaska and Nor- way will indicate the ameliorating climatic effects of warm ocean cur- rents and humidity. EXISTING ARCTIC CLIMATES This is a complex subject which cannot be discussed in this con- nection beyond pointing out certain observed facts which support the thesis of the present discussion. These are the slower heating and cooling of water bodies as compared with land areas, with their respec- tive influence on air temperatures and pressures, their influence on the amount of water vapor in the air and the resulting effect of humidity on equability. The climatic influence of the northward drift of oceanic waters may be illustrated by the course of the present day isotherms over the north Atlantic, a somewhat hackneyed illustration but nevertheless the most striking. I am showing a few of the isotherms for January and July in figures 5 and 6. Those for January which show the full effect of the rapid radiation and quick cooling of the land, contrast most markedly with the slow radiation and cooling of the ocean. At this time the zero isotherm reaches Latitude 35° in Asia and about Lati- tude 74° north of Norway, a difference of 39°. Much the coldest place is in northern Siberia which is 10° to 20° colder than at the pole itself. The — 30° isotherm reaches almost to the pole north of the Atlantic and swings to approximately Latitude 55° in Siberia—a difference of about 35° of latitude. The midsummer isotherms naturally smooth out these curves somewhat but even at this season the isotherm of 5° swings from about 62° in southern Greenland to 80° just west of Spitzbergen and the oceanic effect is clear as far eastward as Nova Zembla. A few figures quoted from Sir John Murray’s calculations will serve to emphasize the relations referred to. The energy radiated by the lowering of the temperature of a cubic meter of water 1° is sufficient to raise the temperature of more than 3,000 cubic meters of air 1°, and a second calculation shows that the heat released by lower- ing by 1° a stratum of water 200 meters deep and of 700,000 square kilometers area would suffice to raise the temperature of a stratum 18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 of air 4,000 meters deep over the whole of Europe on an average Or 10 I have not attempted to evaluate the effects of the present ice cap on Greenland or of the present altitude of the land surface, as all Fic. 5 Midwinter isotherms at the present time. I wish to do in this brief discussion is to emphasize in a graphic way the major thermal effect of land and water. The Arctic is an oceanic basin and shows a remarkable climatic contrast with the elevated glacier-covered Antarctic continent. A few of the probable climatic effects which would follow if the Arctic re- 4 No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 19 ceived ocean waters from the Pacific or across Eurasia from ancient Tethys, or became ice free during the summer are discussed very briefly in a subsequent section of this paper. Fic. 6—Midsummer isotherms at the present time. SOME PALEOBOTANICAL MISCONCEPTIONS Although I have on previous occasions emphasized the lack of climatic value of most of the plant types which paleobotanists have relied upon as indicating tropical climates, this subject should not be passed over without some comment in the present connection. The principal evidence upon which tropical climates have been pred- icated falls into three somewhat dissimilar categories. First it rests upon tradition which never had any basis. For example the concep- 20 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 tion that the flora of the Carboniferous grew in a supertropical climate with a humid atmosphere charged with carbon dioxide, of which Koppen and Wegener make such specious use, had as its original basis the 18th century idea that the strange plants associated with the coal had been swept to Europe from the tropics by Noah’s flood and the further fact that the habit and venation of certain fern- like Carboniferous plants, now referred with strong probability to the Pteridosperms, resembled certain existing tropical ferns. European students accustomed to the modern accumulations of peat in high latitudes concluded quite as illogically that peat could not accumulate in the present equatorial region because of the rapid oxidation there, so added carbon dioxide to make growth extraor- dinarily rapid and great moisture to prevent rapid oxidation. The carbon dioxide stimulation would also conveniently account for the enormous size of some of the calamites and lepidodendrons as com- pared with their diminutive survivors the equisetums and clubmosses. Then Koorders and Potonié described a peat bog from Sumatra and others have been subsequently described from other tropical lands, and there has been much readjustment of views, which might have been accomplished much earlier if the experts on geological climates had ever visited the tropics or even consulted the report on the peat deposits of Florida published by the Geological Survey of that state. There is not space at my disposal to follow the vagaries of opinion, but it may be stated in the most positive way that temperature or the position of any region with respect to the equator, that is between hot or cold climate, is not a factor in the formation of either peat or coal. Second the tropical idea relies on representatives of long lived, vigorous groups with very many species, which either in the past or ii the present have become adapted to a variety of habitats, as is usually the case in large vigorous groups of all kinds of organisms. As outstanding examples I may cite just a few types such as the palms, and figs, or such genera as Cinnamomum and Zizyphus. The great bulk of the existing palms are tropical and they are one of the first types of plants visualized when we think of tropical climates, whether we picture the Arab and his date palms or the South Sea Islander and his cocoanut palms. Nevertheless certain palms extend to approximately 39° South in Chile, 44° South in New Zealand, 34° North in California, 35° North in North Carolina and 36° North in Japan, and commonly are hardy several degrees north of their nat- ural limits, as in the Sacramento valley in California, or in southern * Not considering the subtropical arid belts of high pressures. No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 21 France. The greater limits of cultivated forms is usually not a result of cultivation so much as it is of selecting the species that will grow in a particular environment. In nature the proper species is subject to the historical factor of there having been ancestors in the region or in a region offering access to the particular region. For example our native Californian palm (Neowashingtonia) is a plant of sandy alka- line. soils whose range seems to be conditioned by the geologically late submergence of the Colorado Desert area, and to bear no relationship to latitude. In the present tropics certain palms range upward to nearly 10,000 feet, as in the wet parts of the northern Andes (Ceroxylon, Geonoma, etc.). The genus Ficus, to which the cultivated fig belongs, is one with upwards of 600 existing species of a great variety of habitats, and with probably as many fossil species, extending back to the dawn of the Upper Cretaceous. Various members range well into the temper- ate zone, both geographical and altitudinal. The cultivated fig gener- ally ripens its fruits in Baltimore. I have seen it in the temperate altitudinal zone in Bolivia, and Weberbauer* records an altitudinal range for it through 8,255 feet in Peru. Cinnamomum is the genus to certain members of which the names cinnamon and camphor trees are applied. The genus is large and ranges from the Upper Cretaceous to the present. Although the ma- jority of existing species are confined to the tropics some extend for considerable distances into the Temperate Zone, in fact the com- mercial supply of camphor comes in large part from Formosa and Japan, and the tree is hardy in the southern parts of the latter country. Introduced into Florida it has been widely seeded by birds and is perfectly hardy throughout that state. Zizyphus is a large genus also going back to the Upper Cretaceous, whose present center of population is southern Asia and the Sunda Islands. The new world species are practically confined to the tropics, but in the old world there are distinctly temperate species in southern Europe and eastern Asia. It has run wild in Louisiana, and charac- teristic fruits occur in the Pleistocene of the Atlantic coastal plain as far north as Long Branch, New Jersey. Obviously as a fossil. Zizyphus entirely lacks a tropical significance. A third source of error is the common assumption that because a particular type of plant has its home in the equatorial zone it is neces- sarily a tropical plant. The type most frequently alluded to in fossil Arctic floras as indicative of a once tropical climate is the tree ferns, the term embracing a variety of species in several genera, * Weberbauer, A., Archiv. Asoc. Peruiana Progreso Ciencia, tomo 2, p. 60, 1922. i) i) SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 As a matter of fact tree ferns reach their maximum development in temperate rain forests, as in New Zealand (Lat. 40° S.), or in similar situations in tropical uplands, as was pointed out by Alexander von Humboldt over 100 years ago. They reach their greatest pro- fusion in South America in the temperate part of the montafia zone of the eastern Andes. They grow luxuriantly on the mountains of central Africa at altitudes where they are buried in snow for part of each year, and as fossils their climatic significance is wet temperate and not tropical. There are a great many other genera or species in the same category. I have seen Anonas and Ingas (cultivated) at 10,000 feet in the Andes perfectly hardy, and a large number of generic types that are com- monly thought of as lowland tropical above the tropical altitudinal zone—such things as Dodonaea viscosa, Sapindus saponaria and Swietenia mahagoni. In fact it was my own observations in the Andes that first turned me from the paleobotanic tropical tradition. Another misinterpreted type is the Gleichenia type of ferns (now segregated in several genera) very common in the Cretaceous floras of Greenland, but largely absent from the northern hemisphere in recent floras. Although commonly confined to low latitudes at the present time, it is by no means confined to the tropical altitudinal zone ; in fact, where I have seen it (Yungus of Bolivia) it is promi- nent above the tropical zone, as it is also in Hawaii, Peru, Ecuador, Asia, etc. Representatives reach 54° South in Chile and 40° South in New Zealand. All this is related in any account of fern distribution (e.g., Die naturlichen Pflanzenfamilien, 1902), and still Gleichenias, along with palms, cycads, and tree ferns always appear in the paleobotanists tropical repertoire. I suppose that constant reiteration of facts like the foregoing will have to be continued over many years before the news reaches those who write on paleoclimatology, and at least another generation will elapse before writers of geological text books cease to talk about the tropical climate of Tertiary Greenland. Juniperus communis Linné is found as far north as the North Cape, which is at least 20° farther north than any other member of the family Cupressinaceae is found in the Eastern Hemisphere (Nat- horst, 1911). Sassafras, of the mostly tropical family Lauraceae, ex- tends northward to southern Maine, or about 13° beyond the bulk of the family. Diospyros, of the mostly tropical family Ebenaceae, extends northward to southern Connecticut, or about 12° beyond the bulk of the family. No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 23 Nor must it be lost sight of that at those times in the past when certain groups were varied and abundant, as were the seed ferns in the Paleozoic or the cycads in the Mesozoic, they were quite likely to have shown the features of dominant organisms, both plant and animal, and to have occupied more environmental niches than the depleted survivors of the cycad phylum do at the present time. In Newfoundland and western Labrador the larch (Larix ameri- cana), the balsam poplar (Populus balsamifera), the paper birch (Betula papyrifera), and the balsam (Abies balsamea) fail to reach the Straits of Belle Isle (52°) whereas they all extend far above Latitude 60° in Alaska and the first crosses the Arctic Circle. Podo- carpus just fails to reach the Tropic of Cancer in Cuba. A Chilean species reaches 42° South Latitude in Chile. The northern limit of forests crosses the Arctic Circle in Alaska and reaches 70° North Latitude in Norway, the latter 20° north of the tree line on the Atlantic coast of North America. EXPLANATION, OF PAST ARCTIC CLIMATES It is perhaps fatuous to point out that climate, either present or past, depends upon a variety of factors, both cosmic and terrestrial. Of the former the only one that is of practical importance is solar— that is, radiant energy from the sun, since it is inconceivable that other heavenly bodies or the introduction of kinetic energy by meteor- ites exert any appreciable effect. The amount of solar energy reaching the earth depends upon the sun’s activity, which is variable; on the distance of the earth from the sun, which is also variable ; and more practically in so far as terrestrial climates are concerned, on the condition of the earth’s atmosphere, especially with respect to the amount of ozone, water vapor, carbon dioxide, and dust present, all of which again are variable. The lati- tude, determining the angle of incidence of the sun’s rays, is an obvi- ous factor, as is also the geographic pattern and the topography, in- cluding altitude under the latter. The geography determines whether the sun’s energy falls on the land or the water, it determines the temperature gradient between the equator and the poles and the con- sequent force of the planetary winds and ocean currents, and in less obvious ways is of the greatest significance, as the following illus- tration will make clear. The North and South Equatorial currents in the Atlantic are so situated that the South Equatorial, the stronger and the larger of the two, is divided by Cape San Roque into a larger, northern or Guiana current; and a smaller, southern or Brazil current. Some authors, 24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 e. g., Guppy, are inclined to consider the South Equatorial as bipartite throughout, calling the Guiana current the Main Equatorial current. The point is immaterial in the present connection since all I desire to show is that the shape of eastern South America and the latitude of Cape San Roque are purely fortuitous in so far as their relation to climate is concerned, and yet if the latter had happened to lie a few degrees north of its present position much of the water that ultimately contributes to the Gulf Stream would have turned southward to aug- ment the Brazilian current, and the climate, especially of Europe and the Arctic, would be profoundly modified. It has been estimated that if Cape San Roque were 2° north of its present position there would be a shift of 4o% of the Equatorial current which would be deflected southward instead of northward. The same results would be attained if the southern trades were not stronger and more constant than the northern trades, because of the relative amounts of land and water in. the northern and southern hemispheres. Scant attention will be devoted to the various theories that have been advanced to explain geological climates. These range from that of Croll, in its original or modified form, based upon the eccentricity of the earth’s orbit and the obliquity of the ecliptic, which was doubt- less a factor at all times, but hardly a controlling one ; through those theories that rely on changes in the atmosphere, such as alterations in the amount of carbon dioxide (Tyndall, Arrhenius, Chamberlin)’ amounts of volcanic dust (Humphreys), to the extreme form of the hypothesis advanced by Manson, and elaborately defended by Knowl- ton, that a combination of cloudiness progressively diminishing dur- ing earth history, and a terrestrial control due to a cooling earth, instead of a solar control as at present, are the primary factors which explain past climates. Finally there are those highly speculative hypotheses such as Chamberlin’s reversal of the oceanic circulation, and a group which predicate a wandering of the poles in various ways, now fashionable in the revived form put forward by Wegener. I have quite possibly omitted other proposals that might be men- tioned, and I have now to mention the theory, if it can be called a theory, which is the main thesis of the present paper, namely: that it seems to me possible to interpret geological climates in the light of demonstrated changes in topography and geography, including under the latter differences in the distribution of land and water and the transfer of energy by currents. ‘It is of interest to note that Neumayr in 1883 pointed out that excesses of CO, would be impossible since the absorption by the oceans would maintain an almost perfect balance. NO. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 25 This idea, as applied to the Pleistocene glaciation, was first advanced, I believe, by Lyell, and in its more general application has been re- cently put upon a scientific basis by Brooks, with whom I am in perfect agreement to the extent of the evaluation of these as major factors, but also in my firm conviction that arm chair philosophy with its fondness for highly speculative and catastrophic hypotheses, has no place in a uniformitarian world or in 20th century science, but be- longs in the medieval age of human thought. Climate, in a uniformitarian geology, occupies a somewhat anoma- lous position, which the scientific world has been slow to recognize, namely, that the history of the human race has been run under cli- matic conditions which, from the point of view of earth history, are exceptional. Man was evolved subsequent to the relative elevation and the great extension of the continents which ushered in the Pleis- tocene glaciation, and therefore what is normal in human experience, is abnormal for the bulk of geological climate. While, therefore, we recognize that the climatic factors and the meteorological elements are the same now as always, their combina- tion to form actual climates has depended upon a great many factors, among the chief of which was the size, shape, position, and relative elevation of the land masses. It may be remarked parenthetically that numerous theories of the causes of, or descriptions of geological climates have been advanced by students ignorant of meteorology, and also usually ignorant of the relationship of organisms to their environments, and the last is strikingly true of Koppen & Wegener’s recent Die Klimate der geologischen Vorzeit (1924). In attempting, a few years ago, to explain the extension of floras nearly to the poles during the late Eocene, I relied chiefly on the sub- mergence of continental areas in the middle Eocene and the resulting free oceanic connections at that time between equatorial and Arctic waters, pointing out that these Arctic floras were coastal floras and therefore under the régime of an oceanic climate.’ Essentially the same explanation was put forward independently in connection with Jurassic climates a few months later by Kerner von Marilaun.’ An additional and important factor has since been brought forward by Brooks,’ who points out that the temperate gradient is a simple func- tion, whereas the influence of the ice increases as the square of the * Berry, Edward W., A possible explanation of upper Eocene climates. Proc. Amer. Phil. Soc., Vol. 61, pp. 1-14, 1922. 2 Kerner von Marilaun, F., Sitz. k. Akad. Wiss. Wien, 1922. * Brooks, C. E. P., The problem of mild polar climates. Quart. Journ. Roy. Meteor. Soc., Vol. 51, pp. 83-94, 1925. 26 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 radius. Hence a coincidence of minor factors sufficient to effect an overturn in the one or the other direction, that is, toward ice forma- tion or melting, would suffice to induce a wide extension of polar ice, or to prevent the polar regions from maintaining a permanent ice cap. If this is true then it seems quite probable that there was little polar ice during those times already enumerated when temperate floras invaded the polar regions. This would mean profound changes in the distribution of barometric pressures and consequent wind cir- culation, and in fact, in all of the elements which constitute climate. It would mean that in western Greenland, for example, where the most extensive late Eocene Arctic flora has been found, the present day glacial anti-cyclonic winds would be replaced by westerly or south- westerly winds blowing from the relatively warmed waters of Baffins Bay, and this would satisfactorily explain the details of the floral facies. This does not mean that there would be tropical climates in the Arctic or that the region would not be ice bound in the winter season. The protective effect of snow, and cold sufficient to cause a cessation of plant activity during the Arctic night are a physiological necessity. Otherwise most vascular plants could not maintain them- selves. They tend to die either if active in darkness or if exposed to desiccation by air and wind when the ground water is frozen. Regarding the general history of discussions of geologic climates I believe that most paleontologists who have written on this topic, especially those dealing with the pre Cenozoic periods, have had little basis in fact for their speculations. They seem to me to be utterly oblivious to the great amount of modern work on the distribution of marine organisms; and their ideas of the climatic significance of a trilobite, eurypterid, or ammonite is purely a tradition inherited from the distant past when all strange organisms were associated with torrid climates. In stating my belief in a greater uniformity of climate during the past than obtains at the present I do not wish to be understood as advocating such unsound beliefs as the entire absence of zonation, such as many paleobotanists have defended (Jeffrey, Knowlton), or a similar uniformity throughout all time. Both are equally disproved both by geological observations and meteorological principles. Jeffrey, for example (Anatomy of Woody Plants, Chapter XXX, 1917), holds that the more ancient the epoch the warmer the climate, and that there has been a gradual and progressive refrigeration during geologic time ; that the organization of secondary wood in extinct plants furn- ishes the most reliable evidence of climatic conditions; that toward the end of the Paleozoic, growth rings appeared in woods in high latitudes ; that in the Triassic, growth rings were developed ten degrees No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 27 nearer the equator than had been the case during the Paleozoic ; that in the Jurassic, the tracheids first developed tangential pitting which was at the end of the annual ring, and accompanied by storage ele- ments (wood parenchyma). None of the statements in the foregoing paragraph are facts of observation. There is no geological or paleontological evidence indi- cating a progressive climatic cooling during geologic time, and the Permo-Carboniferous glaciation was admittedly more extensive than that of the Pleistocene. The presence or absence of growth rings exhibits what might be called constitutional variations quite indepen- dent of climate, not that they really are independent, but two associated species under an identical climate will behave differently with respect to this feature of their anatomy. Growth rings appear in some Pale- ozoic woods many degrees nearer the equator than Jeffrey admits,’ and in marine formations deposited off low coasts so that they cannot be considered to have been upland types. Several Lower Carbonifer- ous examples have already been cited. The Paleozoic genus Mesoxy- lon shows tangential pitting, which, according to Jeffrey, first appeared in the Jurassic; and the citation of a wood from the Triassic of Arizona as an argument for the advance equatorward of cooler cli- mates during the early Mesozoic is particularly disingenuous, as it is perfectly clear that the growth rings in this case have nothing to do with temperature, but are due to periodic lack of moisture in that region, as exemplified by the contemporaneous gypsum deposits. Similarly in the recent elaborate work on geologic climates by Kop- pen & Wegener, already alluded to, these authors offer explanations to account for climates during the successive geologic periods, which climates have not been proved to have ever existed. As I have pointed out on previous occasions, paleobotanists in general have entirely lacked objective experience outside the temper- ate zone, and have invariably overestimated temperatures. They have been prone to use the present distribution of the fancied or real rela- tives of their fossil forms as if temperature were the sole factor in the environment, and have stopped with the geographic occurrence, with the apparently simple trust that all lands in the equatorial zone were at sea level and wet tropical. A sojourn in the Arctic climate beneath the equator on the backbone of South America would do much to correct this misapprehension, as would also some experience in the temperate rain forests of different regions. I had intended to indicate current conceptions of contemporaneous paleogeography on the maps showing the plant localities but have * Several have been named in the preceding paragraph devoted to Mississippian Arctic plants and others could be added. 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 not done so although I did publish such a map for the Eocene in 1922. This intention was abandoned for the reason that it was not possible to compile maps that did not cover too much time nor in which the extrapolation was not so great as to destroy any real value. Arldt has compiled maps which represent a synthesis of opinions and showing the areas of agreement and disagreement among special- ists and to these the reader is referred. The debatable North Atlantic continent and the Gondwana continent would, if they ever existed, have had a profound effect on climate. Whether or not they were ever realities [ am not prepared to say. I can, however, make the following statements with a considerable degree of certainty, namely : That there was a wide extent of land in the Northern Hemisphere from late Mississippian through the Permian. That the Arctic was Jand- locked in early and middle Triassic and that there was a wide trans- gression of the sea in the Neo Triassic. That the maximum Jurassic transgression was about Oxfordian; that of the Lower Cretaceous was in the Neocomian ; that of the Upper Cretaceous was in the Emscher- ian; that the late middle Eocene was a time of wide sea transgression and low lying lands; and that during the Miocene, the age to which Heer assigned the Arctic Tertiary floras, the amount of land in the Northern Hemisphere was nearly as great as it is at the present time. It will be seen that there is a correspondence between times of sea extension and Arctic floras and times of land extension and no traces of Arctic floras. This correspondence is not exact, and so little of paleogeography is objective, that I would not want to appraise it for more than it is worth, but in so far as it 1s known it does offer corroboration of my thesis. I had expected to attempt an estimate of the meteorological condi- tions at the various times at which fossil floras are found in the Arctic, but after abandoning any hope of getting reliable paleogeographic data I have also abandoned the former. Brooks has published some interesting meteorological estimates using as a basis those parts of Arldt’s maps where authorities agree, but it should be pointed out that majorities are quite as likely to be wrong in science as in politics, and if generalizations are valid (which of course they are not) then minorities are usually right. There are, however, a few considerations that may be put forward as having a high degree of validity, namely the importance of ice as a third factor, added to the long recognized rotational (planetary) and geographic (distribution of land and water and altitude) factors in influencing the distribution of pressures and consequently of pre- vailing winds. And also the effect of the volume of fresh water car- No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 29 ried into the Arctic basin by rivers in the formation of ice and the effect of current-borne ice in maintaining subnormal density and con- sequently the identity of the present day cold currents as they move southward. Once they become of normal density they disappear below the surface and lose their climatic influence. Another factor of considerable importance climatically, especially in connection with the theory of Brooks, is the amount of reflection from the earth’s surface. I do not have the exact figures, but estimates given to me orally by W. J. Humphreys, are about 7 per cent from land or water and about 70 per cent, or ten times as much, from the surface of snow and ice. If there has been the wide fluctuations in polar ice as Brooks predicts, then reflection is a factor which can not be safely neglected. At the present time in high latitudes the prevailing wind circula- tion is easterly with a southward moving component at the surface. If the ice cap were gone we would have westerly winds in high lati- tudes with a poleward component at the surface. If Bering Strait was open and less shallow, a great volume of warm Pacific water would pour into the Arctic and greatly ameliorate the climate, as would also be the case if a Cretaceous seaway bisected North America, or a Devonian or Eocene seaway bisected Eurasia, such as are shown on current paleogeographic maps. If the best avail- able sources are utilized in plotting Eocene seaways nearly all the Tertiary coal occurrences and floras in the Arctic range themselves along the easterly coasts of such seaways. CONCLUSIONS The major factor in the polar extent of temperate floras is not primarily the direct effect of temperature so much as it is the fact that above 32° F. water is a liquid and below 32° F. it is a solid. Asa Gray said “ Plants are the thermometers of the ages.” I have no doubt that terrestrial vegetation when properly interpreted is the safest guide to geological climates, but as thermometers they are pretty poor and we have no means of calibrating them, There is no unequivocal botanical evidence of tropical or subtropical climates at any time in the Arctic. There is no evidence from paleo- botany of a lack of climatic zonation at any geological period from which fossil plants are known, although at such times the evidence points to a relative mildness and a lack of sharp zonation, as com- pared with the present. The distribution of the known fossil Arctic floras with respect to the present pole proves conclusively, as Seward pointed out in 1892 (p. 53), that there could have been no wandering pole. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 7 THE ATMOSPHERE AND THE SUN BY H. HELM GLAYTON D °Fe Soo, D “0” a (PUBLICATION 3062) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION JUNE 9, 1930 i i SS 7 ' 7 i ; v5 I a 7 i - 7 5 < r | ‘ \ The Lord Baltimore Press BALTIMORE, MD., U. S. A. tHE ATMOSPHERE AND “AE SUN By H. HELM CLAYTON CONTENTS PAGE IGimy SOY G NBIC 6 (oh 0 Vale ta heaps ORR oi ict oko. bcc ie co PRC cd CRAMER RROEO a eeepc ae I Ils SOD P NG DE nnleXee ein tarts eit Sete tnt bina te mines Sa cimiGe an Bema eer Ree I II. Latitude effect of solar changes on the earth’s atmosphere............ 4 Mee Seasonale sumflisemcesy srcsye te rete ever daciete mite eel Serene aneevey cave eevee. & 14 IVA NETTIOSDMETIG “Waves, Bniec creme oilers ete ciara hein torrente eter erste is aie 18 Weelvelationeor thesweather waves tomsOlan changes. accesses ate eee 29 WitesSOlar cycles) and, weatherveycless meme estos cek | sere a eee cies 32 Wiliieedthe use of weather cycles im tofecasting....,..4---755004--+5 secs sece 44 SUMmimmatiyewscnts Siests Sela e eee ee eee oie Se oom pie carseat 48 INTRODUCTION This paper is the fifth of a series giving the results of investiga- tions of the relation of solar activity to atmospheric changes. The earlier ones were published as Smithsonian Miscellaneous Collec- tions, Vol. 68, No. 3; Vol. 71, No. 3; Vol. 77, No. 6; and Vol. 78, No. 4. The author has been stimulated to continue these researches because he believes in their great importance. The interest of Dr. C. G. Abbot and the sympathy and aid of Mr. John A. Roebling have encouraged him in the task and enabled him to undertake much work that otherwise would not have been possible. Miss M. I. Rob- inson has aided in the calculations needed for the discussion. 1 SOLAR CHANGES It has long been known that spots appear on the surface of the sun and that the number and size of these spots varies from day to day, from month to month, and from year to year. More recently it has been discovered by Dr. C. G. Abbot and his associates that the radiation coming from the sun varies ; so that, in general, it is known that the sun is hotter when there are many spots on its surface than when there are few or none. There is also evidence that the heat of the sun varies from day to day and from week to week in short cycies of change. The most convincing evidence of this fact is the comparison of measurements SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 7 Z SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 of solar radiation made at observatories thousands of miles distant from each other, one in the northern hemisphere and the other in the southern hemisphere; so that the chance of both being affected by the same weather changes becomes very small. The solar radia- tion reaching the earth is measured in calories per square centimeter per minute, and averages about 1.940 calories. Table 1 shows a com- parison of observations of solar radiation made simultaneously in northern Chile and in the United States (first in California and then in Arizona) during the years 1918 to 1924. The table shows the frequency of different values observed in the United States for each increase of .010 calorie in Chile. TABLE I1.—Comparison of Solar Radiation Values in Chile and the United States (Number of Cases) Values in Values observed in Chile United —— A — States I.910-9 1.920-9 1.930-9 1.940-9 1.950-9 1.960-9 TAOOOHO sis yrecs aerate ousve I 6 6 6 fe) 0 T#QOO-O ste se ersichevsie sie II II I a) O 0) TQLO=Ol wei tastne ee rs 20 25 II 5 4 (0) TOZO=Oie thoy enters a 18 38 21 5 4 2 THOS O=OCraihe ee Steere 7 23 29 II II (0) THOYOHOe Sse ae 4 6 12 15 16 4 TO5O=Onie,c selehret ee (a) 4 10 10 13 6 THOOO=O lenis xe ete eh () I 3 4 7 5 TO70-Oma nance see (a) I (6) I 3 2 If there were no relation between the measurements at the two stations, the observed values would be scattered through the dif- ferent classes at random. The tabulation shows that a random dis- tribution does not exist ; but for each group of observations in Chile, there is a maximum near the same values in the observations in the United States. There is, therefore, a progressive displacement of the maximum frequency as the solar values increase from 1.g10-9 to 1.960-9, or nearly three per cent of the mean value. The probable error of the measurements is +.006 calorie; so that the solar varia- tion during the interval covered by the observations was more than eight times the probable error of each group of observed values. Since variability in solar radiation has been questioned by some investigators, it is well to state that the evidence of this variability rests on three fundamental and independent facts: (1) The changes in radiation are alike when measured at two widely separated stations, allowing for variations from a middle value due to errors of observation. NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 3 (2) The changes both of short period and of long period in solar radiation are related to visible changes in the number and area of spots, faculae and flocculi seen on the sun. (3) The changes in solar radiation are correlated with other phe- nomena such as certain changes in terrestrial magnetism, in radio- receptivity, and meteorological changes which are known by other evidence to be related to solar conditions. The critics of solar variability have pointed out that the measured variations have decreased as the accuracy of the observations in- creased and that in the earlier observations the effects of water vapor DAYS BEFORE DAYS AFTER G 4 2 0 i i f i ie i i a. re 20 1.952 | | | Ceriter | of sun 1.951 ( 1 \ 1.950 wogeedeee., F SHOVE eseStesocc: Se ss Neakk= nese ssaeeoer el aii am CAAA ES ——s unit Re aces as Glam ae) Be CET. (ate a — {ff SAH a Fic. 16.—Pressure in 3.77-year period. ress here indicated would carry the wave from pole to Equator in one period. In figure 16 is found a period in which the unit of time is years instead of days. The period of oscillation in pressure is about four years. It was taken to be 3.75 years, or one-third of a sun-spot period of 11.3 years, and averages were made for each three suc- cessive oscillations of 3.75 years. The continuous curves show the NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 25 averages. The letters a, b, c, etc., show successive maxima. The data were derived from ‘“ World Weather Records” and cover the con- tinent of Asia where the data are more complete for different lati- tudes than in North America. It is seen from the plot that the maxima and minima of the period occur first in high latitudes and successively later at stations nearer the Equator, at least down to about 30° latitude, taking about three years to move from Obdorsk, 66° N., 66° E., to Ley, 34° N., 77° E. In the equatorial belt between 20° N. and 20° S. the maxima and minima occur simultaneously at all stations as shown by the results for Madras and Batavia. However, from figure 16 it is seen that the pressures at Alma Ata, 43° N., and at Batavia, near the Equator, are opposite in phase, which is further evidence that this wave traversed go° of latitude in one period of about 3.75 years. A recent study of 2- and 34-year waves in temperature by Ernest Rietschel * shows a rather complex movement indicating a combina- tion of standing and moving waves. That the law of wave progress quoted above holds true in the Southern Hemisphere as well as in the northern is shown by the rate of progress of a temperature wave of about 18 days shown plotted on page 223 of “ World Weather.” “ This wave progressed from Santa Cruz, 50° S., to Cuyaba, 16° S., in seven days, a rate which would carry it from pole to Equator along a meridian in one period of 18 days. The rate of progress of a 7.5-year wave is indicated in figure 22 where the maxima and minima of the waves occur successively later at Stykkisholm, Rome, and Calcutta, the minima and maxima at Calcutta being about 7 years later than at Stykkisholm, These facts render it evident that the rate of latitude displace- ment is a general law for periodic oscillations of all lengths. This law may be stated as follows: Law of latitude displacement of periodic waves—Periodic oscil- lations in atmospheric conditions progress in latitude from point to point along a meridian at a rate that would carry the wave from pole to Equator in one period, whatever the period of oscillation. It is probable that the law of displacement in longitude is equally simple. Figure 14 shows that the 7-day wave progressed in longi- tude about 180°, or half around the world, in seven days. *Die 3-34 jahrige und die 2 jahrige Temperaturschwankung, von Ernst Rietschel. Geographical Institute of the University of Leipzig, Vol. 1V, No. 1, 1920. VoL. 82 SMITHSONIAN MISCELLANEOUS COLLECTIONS ‘0061 ‘€6gr ‘Sggr sysody ‘porsad se9k-$°Z Ul URS WOT dInssaid Jo soinjredaq—ZI ‘dIq LEG) / f- U Lh NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 27 A proportional rate of progress appears to occur in the periodic wave of about 7.5 years. Figure 17 shows the centers of oscillation in a 7.5-year wave on a world map. This map is derived from har- monic values computed from groups of three periods between 1883 and 1913 at 117 stations scattered over the world. It shows the centers of oscillations at the epochs, 1885, 1893, 1900, etc. Con- tinuous lines show equal values above normal and broken lines show equal values below normal. It is not possible with available data to follow the progressive movement of all the centers, but the center over Greenland shows a distinct progress from west to east. This progress will be evident from figure 18 which shows the centers of oscillation in the area between 50° W. and 120° E. north of the Equa- tor when the epochs are taken successively two years later. The results in figure 18 are derived from the data of 48 stations taken from ‘‘ World Weather Records.” In 1885 there was a marked excess of pressure over Greenland (see fig. 17) ; in 1887 this center of excess pressure is displaced to Norway; in 1889 this center is over the northern part of central Siberia; two years later, in 1891, it is over the northern part of western Siberia. The progress of the centers is shown by small cir- cles in the upper chart of figure 18. The circles show that the center was displaced eastward about 180° in a period of 7.5 years or at a rate which would carry it around the world in two oscillations of this period. In his study of the 2}-year period Mr. Clough’ found that the epochs at Portland, Oregon, preceded those at Toronto by about 0.75 year. The difference in longitude is 43°. At that rate the epoch would move about 150° of longitude in one period, or approximately around the world in two periods. The charts given by Dr. Weickmann in his study of the 24-day period referred to previously do not show the drift in longitude so clearly as the drift in latitude. However, in his charts there are found centers of maximum departure which show a drift in longi- tude. A center in the Aleutian Islands on December 10, 1923, moved eastward across Canada to Labrador in 11 days, which is at the rate of about one period for 180° of longitude; but a center near Green- land moved eastward to northern Siberia and then retreated. The longitude drift of the waves is, hence, not so clearly defined as the latitude drift ; but there is undoubtedly a trend which may be stated as follows: * Monthly Weather Review, Vol. 52, No. 1, p. 30, Jan., 1924. SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 p ne: q re y £3 t a eH) 5-yea ae ete een | rg. 18.—Departures of pre 1880, 1 ae NOS 7, THE ATMOSPHERE AND THE SUN—CLAYTON 29 Law of longitude displacement of periodic waves.—Periodic waves tend to drift eastward at a rate of 180° of longitude in one period, whatever the length of the period. The centers of greatest departure are found in high latitudes, 60° to 80° from the Equator. There are several factors which make this drift toward the east difficult to follow. First there are the factors depending on solar changes described in the latitude effect and which are nearly instan- taneous with solar changes. There are also seasonal factors and probably others which influence the results. Examining the successive charts in figure 18 it is found that the magnitude of the departures in the 7.5-year period decreased rap- idly as the central areas passed into Siberia and increased again over Kamchatka. This enhanced intensity in the departures coincided with a maximum of solar activity as will be seen later. Another disturbing factor is the formation of centers of distur- bance moving at right angles to the normal waves. When waves of high pressure and low temperature are advancing from the north- west, low pressure areas form in front of them and advance from southwest to northeast. These disturbances advancing toward the northeast are particularly frequent over the warm ocean waters to the east of Asia and of North America. These cross currents greatly complicate the normal movement of atmospheric waves and make analysis of the data difficult. V. RELATION OF THE WEATHER WAVES TO SOLAR CHANGES If the values of solar radiation observed by the Smithsonian Astrophysical Observatory simultaneously with the pressure waves are treated in the manner just described they show in each case wavelike changes of the same length as the pressure waves. Figure 19 shows the successive means of four periods of seven days in solar radiation during November and December, 1927, com- pared with the atmospheric pressure observed at the same time at Eagle, Alaska, and treated in the same manner as in table 6. The dotted curves in each case show the harmonic values of the 7-day wave computed from the data. Compare this diagram with the plots in figure 12. Figure 20 shows the means of successive values of a period of 13.6 days in solar radiation and in pressure derived from the means of two periods. This diagram may be compared with the plots in fig- ure 13. The dotted curves in figure 20 show harmonic curves com- puted from the data. 30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 NOV. 5, 1927 Fic. 19.—7-day period in solar radiation and pressure. MAR. 2l, 1927 MAY 10 Pa oe a Mead asa a ee aa SSURE EAGLE ,65 IN., 141 Ww. eevee Fikes AALS Rages IG. 20.—13.6-day period in solar radiation and pressure. NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 31 Figure 21 shows the observed values of solar radiation during December, 1923, and January and February, 1924. These values are compared with the observed values of pressure at Spitzbergen and at Hamburg. A 24-day period of oscillation is evident in each case and this oscillation is shown by the dotted curves computed from the data in each case by harmonic analysis. Pressure data from all DECEMBER 1923 JANUARY 1924 FEBRUARY | 9 10 20 FAN W Ged | 1 Da a a ASSURE IN SPITSBERGE! Fic. 21.—24-day period in solar radiation and pressure. over the northern hemisphere were treated in this way for a period of 24 days by Dr. Weickmann and showed a systematic wave movement from the polar basin southward. For the study of long periods, no values of solar radiation are avail- able; but the 7.5-year period shows a distinct relation to sun-spot changes. Figure 22 shows a plot of consecutive means of three periods of 7.5 years. This period is one-third of Hale’s sun-spot period of 22.5 years, and the mean of the three periods eliminates the I1.3-year sun-spot period which is one-half of Hale's period. 32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 Pressure curves are plotted for five widely separated stations. These plots show distinctly an oscillation in the atmosphere of the length of 7.5 years and a progress southward from high latitudes. 1880 ee Saas BMAive oa Sa a a PRESSURE STYKKIS|HOLM , 65 NI, 23°W. Wi. a Sey 6 NEAT NG Le Ga 8 ya eT NE Ad AE Sn A pf __¥ |__| Nf ne i A enna eM a7 Berea o Faas Fic. 22.—7.54-year period in sun spots and pressure means of 3 periods. VI. SOLAR CYCLES. AND WEATHER (GYCLES From the preceding investigation it is evident that atmospheric and solar conditions show wavelike changes of a periodic nature. The question has long been a challenge to investigators, as to whether there are fixed and regular cycles in weather and in solar changes. If such regular cycles could be found, it would greatly assist in unraveling the complexities of the weather and in forecasting future occurrences. There is a dominating period of about II years in sun- spot numbers, and many efforts have been made to find this same NOle 7 THE ATMOSPHERE AND THE SUN—CLAYTON 33 dominating period in weather changes. Such a relation has not been found and the reason appears to be that weather changes follow changes in solar radiation more closely than they do sun-spot num- bers, and solar radiation is more variable and shows a more complex periodicity than do sun spots. When the 11-year period 1917 to 1928 is analysed harmonically for sun spots and solar radiation, the results in table 7 are obtained. TasLe 7—Harmonic Terms for 11%4-Year Period in Sun Spots and Solar Radiation Sun-spot numbers ; Solar radiation (om A aren ar ae \ oe 8 SE Amplitude Amplitude Epoch 1917.5 in numbers Epoch 1917.5 in calories Ax = 104° Gis= 35:3 Aa = 64° di = .009 Ag 274 aZ—70 AG 2385 a2 = .004 Ag 305" a3 = 10.6 AG 505 a; = .008 AEE Ee a; = 6.0 As = 330° cJ—005 These results show that in a general way the oscillation in the num- ber of sun spots and in the intensity of solar radiation are in the same phase—that is, when one increases the other increases ; but the amplitudes of the changes are very different. The amplitude of the primary oscillation, a,, in the sun spots (the 114-year period) is decidedly predominant while in the solar radiations the amplitudes of the harmonics of 5, 4, and 4 of 11.3 years, a2, a3, and ay are almost as large as the primary a. The pressure data for tropical stations for the 11 years 1917 to 1928 are not available at present, so that a com- putation of pressure changes was made by going back two periods of I14 years to January, 1890, and computing the harmonic terms from the mean pressure of nine equatorial stations extending from Quix- eramobim in Brazil eastward across Africa and the Indian Ocean to Malden Island in the Pacific. The data covered two 11-year periods, 1890-1913, and the epochs were taken at 1895.0= 1917.5. Taste 8.—Harmonic Terms for 11%4-Year Period in Pressure, 1890-1913 Mean Pressure of 9 Equatorial Stations Epoch 1895.0 = 1917.5 INS 57 ds = 0.36 mb. 200 a2 = 0.32 mb. As = 265° ds = 0.25 mb. AGT 50 as = 0.35 mb. This comparison indicates that in the 1t14-year period in pres- sure in the Tropics, the phase is in general terms opposite to that of sun spots and solar radiation, and hence when these increase the 34 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 pressure decreases. This fact is also made very apparent by com- paring the individual periods in sun spots with pressure from 1870 to 1920. It is also evident that the amplitude a, of the 11-year period is not dominant as in the sun-spot period ; but as in the case of solar radiation the subharmonic terms a», a3, and a4, are almost as large as the primary a. In order to compare the harmonic terms of the 114-year period in pressure in equatorial regions with those in other latitudes, the mean pressure was obtained for each 10° of latitude in the northern hemis- phere for each year from 1890 to 1913. A period of 23 years was taken because from Hale’s observations of magnetism in sun spots the complete period of the sun spots is about 22.6, so that 11.3 years becomes the second harmonic of this period. From the data thus obtained harmonic terms were computed for each zone of lati- tude and are given in table 9. The phases of the periods varied for TABLE 9.—Amiplitudes of the Harmonics of a 22.6-Year Period in Pressure dz as a4 a6 as do4 a48 a7z2 Zones of No. of 11.3 7.54 5-65 3-77 2.83 Tes 5.7 3.8 latitude sta. yr. yr. yr. mo. mo. mo. yr. yr. : 70°-80° N. 2 0.60mb. 0.65 mb. 0.94mb. 0.92 mb. 1.12mb. 2.40 mb. 2.50 mb. 3:75 mb. 60°—70° 14 0.59 0.61 0.77 0.88 0.86 2.09 2.78 Pray 5SOn-60+) 2 10:34 0.38 0.46 0.61 0.76 1.32 1.60 1.28 40°-50° 25 0.32 0.42 0.43 0.45 0.51 1.22 1.10 123 30°—40 30 0.24 0.33 0.40 0.31 0.31 0.67 1.02 0.88 20°—30° i3) 036 0.21 0.29 0.24 0.23 0.62 0.63 0.53 10°—20° 15 0.42 0.25 0.35 0.21 0.33 0.42 0.45 0.40 0°-10° 6 0.36 0.27 0.32 0.25 0.35 0.39 0.25 0.38 Norre.—In computing the harmonics in Table 9 the means of three or of four periods were used in each case except the case of a2 where two periods were used. The observed values from which az were computed covered the entire interval of 22.6 years, while the values from which a72 were computed covered only one twenty-fourth of this interval. ° each latitude as it was evident they must do from the preceding inves- tigation of wave movement. The striking facts brought out are: (1) The amplitudes of the periods increase greatly in high latitudes where they are much greater than in low latitudes and, (2) the amplitudes of the smaller subharmonics in high latitudes are much greater than that of the period of 11.3 years. This last finding is of the utmost importance to meteorology, because it shows that the shorter periods are of much more impor- tance in the meteorology of high latitudes than the longer periods of II years or more. These meteorological and solar periods are all believed to be harmonics of longer solar periods. Clough found solar periods of 300, 11.3, 7, and 2.5 years, and an analysis of the sun-spot data by Schuster disclosed a number of other NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 35 periods besides the 11-year period. Turner found evidences of a period of 260-280 years from a study of tree rings, Nile floods, Chi- nese earthquakes, and sun spots. (Mon. Not. Roy. Astron. Soc., 1919 and 1920.) According to a recent analysis of the Wolfer sun-spot data made by Dinsmore Alter, published in the Monthly Weather Review of October, 1928, there are solar periods of more than 200 years in length, and the 11-year sun-spot period is a subharmonic of much longer periods. This view agrees with that put forward by Ellsworth Huntington and S. S. Visher in “ Climatic Changes,” 1922, p. 45. My own investigations are in accord with this view, ex- cept that recently the longer periods seems somewhat greater than that given by Alter. Beginning with a period of go years, instead of 84 as given by Alter, I find periods of approximately the following length: Length of solar periods in years: 90, 56, 45, 35, 30, 28, 22.5, 13,85; E20; 14, 10, 9, 8.2, 74, etc. All of these shorter periods are subharmonics of go years, except 56, 35, and 28, which are harmonics of a longer period. They agree very well with meteorological cycles found by Prof. A. E. Douglass * from rings indicating the annual growth of trees in the southwestern part of the United States where rainfall is the most essential factor in growth. The periods found by Professor Douglass pee 2h, 40,26, 22:5-24.0, 20:5, 17-2, 14:2, P1.2-11:7,.10.2,,0.0;.7:6, 0.8 years. A study of periodicities in the Nile floods by C. E. P. Brooks * leads him to pick out the following periods in years: 76.8, 64.6-67.4, 30.85, 33-49, 24.43, 21.81-22.43, 18.32, 16.68, 14.87, 12.50, 10.86- 11.36, 8.33, 7.33, 6.83, 5.52, 3.66, 2.86. It is pointed out that 11 out of 16 of these periods are multiples or submultiples of a period of 22.12 years. This period is somewhat shorter than Hale’s period of 22.6 years; but the difference may be due to the fact that the period actually was shorter during the intervals covered by Brook’s data which go back to the year 641. His data indicate a systematic varia- tion in the phase of this period, so that at the end of about 200 years the phase is inverted as regards epochs 200 years earlier. The researches of D. Brunt* also indicate that there are a great many meteorological cycles, or else there are none. His periods in years derived from the Greenwich temperatures are: 23, 17.5, 15, 8.17, ‘ Climatic cycles and tree growth, Vol. 2, p. 123. Carnegie Inst. of Washington, 1928. * Mem. Roy. Meteorol. Soc., Vol. II, No. 12, 1928. * Quart. Journ. Roy. Meteorol. Soc., Vol. 53, No. 221, Jan., 1927. 36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 7.24; and in ‘months, 64; 60, 42;°37, 20,°25; 214) °10:3-10:5,, as5- 14.7, 13, 124. The researches of Dinsmore Alter* published in the Monthly Weather Review also bear testimony to the multiplicity of meteorological cycles. My own researches have dealt largely with shorter periods of days and months rather than years, principally because there was a much larger mass of data available for discussion. In my earlier studies of pressure and temperature data in the United States.” I found the following periods in days: 3, 3.6, 4.6, 5.45, 6.14, 7.24, 9.1, 11, 18, 22, 29, 44, 58, etc. My recent studies indicate that there are many more cycles and that all are probably harmonics of the sun-spot cycle. A. Defant* in a world-wide study in 1912 found the following periods in days: 4.4, 7.9-8.7, 12.0-13.0, 16.8, 24.5, 31.2-31.5. Arec- towski, Turner, Simpson, Wallén, Myrback, Wasserfall, Schosta- kowitsch, and Kidson have all found short meteorological cycles of various lengths Even the short period cycles of a few days are probably submultiples of much longer solar cycles, the most promi- nent of which is the 11-year sun-spot cycle, or its double value, the 22.5-year cycle. In most cycles the subharmonics of small length are not important, but it has been shown in table 9 that in high latitudes the subhar- monics of the 11-year period in meteorological cycles are of greater amplitude than the primary period of 11 years and that the ampli- tude increases with decreasing length of the harmonic. The sequence has not been followed through for the entire Northern Hemisphere beyond the period of about four months, but the amplitudes of meteorological cycles at stations in the northern United States and Canada apparently increase down to a length of about three days. These shorter periods determine the origin and movement of the ordinary cyclones and anticyclones seen on the weather map. Most investigators of meteorological cycles assume at the begin- ning of their work that any cycle which may exist is constant in amplitude and phase and may by repetition be separated from other changes by which it is masked. This belief is the basic assumption underlying the analysis by the Fourier series or the Schuster peri- odogram. Prolonged investigation usually convinces the research worker that this assumption cannot be maintained. I early became *Monthly Weather Review, Vol. 54, p. 44, and Vol. 55, pp. 60 and 263. * Amer. Meteorol. Journ., Feb., 1895, p. 376; also Amer. Journ. Sci., March, 1894. * Sitzungberichte d. Wiener Akad., Bd. 121, Heft 3. NO. 7 THE ATMOSPHERE AND THE SUN——-CLAYTON 37, convinced that meteorological cycles change both in amplitude and phase. (Science, 1898, p. 243.) Figure 23 shows an analysis of the Wolfer sun-spot numbers between 1890 and 1913 into a period of 22.6 years and its harmonics. It is seen that the chief period is one of 11.3 years, but some of the other periods show a fairly large amplitude of oscillation. 1890 1895 {900 1905 1910 y cA a =) ORE RENE Ce Ce eweee EEE EE PPE PEELE EET Fic. 23.—Harmonic analysis of 22.6-year sun-spot period, 1890-1913. The meteorological data at more than a hundred stations in various parts of the world were analyzed in the same manner. Figures 24, 25, 26, and 27 show lines of equal departure of pressure for the various periods at the time of maxima of the solar periods of the same length. A chart showing the departures at the time of the solar maxima of the 7.5 year period is given in figure 17. 38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 Certain common features stand out clearly in all these charts. First, in the equatorial belt, except possibly over parts of the Pacific Ocean, the pressure is lower than normal at the time of maximum ZZ WRX NA . Jeo = = SS SN fi a a + cee RS | eee ae KY i ees a 7 see aff, tere t See ENN) ces eee hr Semi Si Ea LLL LX = fy Ea z Fic. 24.—I1.3-year period in pressure = 4 of 22.6 years. Departures at time of maximum of solar eae of same length. solar activity in each period. Second, in middle latitudes of the Southern Hemisphere there is a tendency to a belt of pressure above normal which cannot be well outlined on account of insufficient Fic. 25.—5.65-period in pressure = + of 22.6 years. Departures at time of maximum of solar period of same length. observations. Third, in the Northern Hemisphere in high latitudes there is a tendency for the departures to form centers of positive and negative departures, usually two centers of positive departure, and NOS 7 THE ATMOSPHERE AND THE SUN—CLAYTON 39 two centers of negative departure. Fourth, these centers are not in the same geographical position for the different periods and do not remain fixed for successive epochs of the same period. The reasons Fic. 26.—3.77-year period in pressure = + of 22.6 years. Departures at time of maxima of solar period of same length. for these shifting centers are not clear. They are associated with changes in the phase and amplitude of the cycles. Changes in amplitude are both apparent and real. Apparent changes occur where two periods of nearly the same length first pales \ a SP ieee DHE | ILE WZ a Ez Sema Fic. 27.—2.82-year period in pressure = § of 22.6 years. Departures at time of maxima of solar period of same length. strengthen each other when they are in the same phase and then weaken each other when they are opposed in phase. This change will be familiar to most readers from diagrams to illustrate beats in sound 40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 waves. The beats are even more complicated when there are three or more periods of nearly the same length. In such a case there may be an apparent change of phase in one of the periods. Real changes in amplitude are brought about by the influence of longer periods on shorter periods. An example of this is the influ- ence of the annual period on shorter weather cycles. All weather changes are most intense in winter, because then the contrasts in temperature between Equator and pole, between ocean and continent, and between adjacent bodies of land and water are at a maximum intensity and the general atmospheric circulation is increased. Also all periodic changes in the atmosphere are more intense when solar activity increases. The reason for this increased intensity will be clear, first from the fact shown in the early part of this paper that increased contrasts of temperature and pressure in the atmos- phere result from increased solar activity, and second from the fact that the amplitude of the solar cycles increases with increased solar activity. An example of the increased amplitude of solar periods with increased solar activity is shown in figure 22 where the amplitudes of the 7.5-year sun-spot period is distinctly greater during the inter- val 1865 to 1875, when the general level of solar activity was higher, than during the interval 1885 to 1895, when it was lower. The increase of amplitude during the first of these intervals and decrease during the second was also evident in the sun-spot cycle and in its harmonics of 5.65, 3.75, 2.82 years, etc. An example of increased amplitude of meteorological cycles with increased solar activity is shown in figure 28 where a period of 74 months in pressure at Chicago shows a marked increase in ampli- tude at the time of maximum of sun spots in 1917 and a diminished amplitude during the intervals of minima of sun spots in 1913 and 1923-1924. The data for this curve are the means of 10 overlapping periods of 74 months obtained in the manner indicated in table 6. The dotted curves are sine values computed for each individual period. That meteorological cycles change in phase as well as in intensity is also evident. These changes of phase appear to arise from several different causes. First, the solar periods themselves change phase. In most cases this change occurs suddenly and appears to be about 180° AND THE SUN—CLAYTON AI THE ATMOSPHERE NO. ‘(uimutxeu jods-uns 1vou apnyydue jo asevaruT SsulMoys) OsPoIy) Ul ainyesodwia} ur ported syyuow-¢£— gz “DIY | | iS ae ee as | aE FAW ALAIN ADA TAT ETA TA Din atta LSS eae Avera Eee 1 ee Mii ea see ae Yn oe Ee ee ee ee ee a a a Ma E:T TT RT: 1) SR GES Ta 1 42 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 or a complete reversal in phase. Figure 29 shows what appears to be a reversal in phase in the sun-spot cycle. The average length of this cycle is about 11 years, so that two cycles occur in 22.5 years. If the cycles are plotted in 22-year periods as in figure 29 it is seen that in the period 1770 to 1792 the cycle is nearly inverted in phase to the cycles occurring 22 years earlier and 22 years later. It is, however, quite possible that this result is due either to interference of periods of different lengths, or to lack of accuracy in the early observations. No such apparent inversion has occurred since 1800. 10 11 12 13 14 15 16 17 18 19 20 21 22 iS S2NeRRha aaa coal et a Fic. 29.—11-year sun-spot cycle, showing apparent inversion of phase. In figure 30 is given what appears to be a reversal of phase in the 74-year period. This cycle was in one phase from 1848 to 1870, as shown by the broken curve in figure 30, but appears to have been in an opposite phase from 1825 to 1847, as will be seen by the con- tinuous curve in figure 30. This type of change is found in every solar and meteorological period. Brooks and Clough seem to think that shiftings of phase are gradual; but my own researches lead me to the opinion of Professor H. H. Turner that the changes are sudden and of the nature of discontinuities. The change of phase in meteorological cycles is not brought about entirely by changes in phase of solar cycles; but is in part, at least, due to shifting of centers of action in the atmosphere. In the case NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 43 of pressure, when it rises in one part of the world, there is an equiva- lent fall in other parts. These centers of rise and fall are not fixed in position, but shift their position to some extent as illustrated in the case of a 25-month period in a preceding paper of this series.’ The variations in intensity and phase of solar and meteorological cycles makes the investigations of the separate cycles difficult. The use of the Fourier series and of the Schuster periodogram are not well adapted to such work. In order to meet these difficulties I devised the correlation periodogram* which is to a considerable extent independent of variations in intensity of the periods; but does not overcome the difficulty of shifting of phase. The best EAR 2.5.4 5 6 7 6 9 10.00 12 13.4 15.16. 17.16 19 20 2) 22 Ul: NA PERU UT NUT WIZE SE58 il a CPR EERE Fic. 30.—7}-year sun-spot cycle. Means of 3 cycles, showing apparent inversion. N@ N method appears to be to use trial periods of successively greater and greater length and harmonic analysis for each individual oscilla- tion *; then to combine the results for each period into groups of 3, 5, 10 or more. By this method the curve in figure 28 was obtained. This method of research, using groups of 10, has made it possible to analyze and to follow the changes of a great number of meteorological periods and to recombine them by synthesis for a trial in practical forecasting. Such analyses of more than 100 cycles have convinced me that these cycles follow solar cycles of the same length and that they are, mostly at least, harmonics of long solar cycles. "Smithsonian Misc. Coll., Vol. 78, No. 4, p. 48, 1926. * Smithsonian Misc. Coll., Vol. 71, No. 3, p. 15, 1920. * Clayton, H. H., World Weather, p. 376, New York, Macmillan & Co., 1923. 44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 62 VII. THE USE OF WEATHER CYCLES IN PORECASTING Having developed methods of separating and studying various conditions which make up the weather, it seemed important that a test be made of the possibility of using them in practical forecasting. Forecasting future weather conditions in the present state of knowl- edge may be undertaken in at least three different ways: (1) By tracing out the results which follow the increase or decrease in the general circulation of the air with changes in solar activity. (2) By analyzing and following weather waves of different classes. (3) By computing the amplitudes and phases of different cycles found in solar and weather changes and projecting these forward into the future. In regard to the use of the first method, since increased solar activity is attended by a fall of pressure in equatorial regions and by increased contrasts of pressure in higher latitudes, there is brought about an increased atmospheric circulation and certain general con- ditions follow : (1) The cloudy and clear belts of the world are intensified and thus alter the incoming and outgoing radiation. (2) The increased air circulation means an increased flow of ocean waters which brings an increased northward flow of warm water along the east coast of the United States and Japan and an accumula- tion of warmer water in the North Atlantic and North Pacific. The accumulation of warmer waters in these regions especially in autumn brings increased cloudiness and increased rainfall. The increased cloudiness reacts by diminishing radiation losses from the earth and thus further modifying weather conditions. On the other hand the increased oceanic circulation brings increased cold water to the shores of North Africa and southern California, and produces a chain of atmospheric conditions which affect the northern shores of South America and the West Indies and extend well out into the Pacific. A parallel set of changes is produced in the Southern Hemis- phere in an opposite way on the east and west sides of the con- tinents. When solar activity diminishes the reverse conditions prevail. (3) Increased solar activity brings also an increased flow of air over the continents and with it an increased rainfall in certain regions and a decreased rainfall in other regions. The distribution of pres- sure and attendant conditions is to a large degree influenced by the seasons. NO. 7 THE ATMOSPHERE AND THE SUN—-CLAYTON 45 Hence, to follow the sequences of weather resulting from increased solar activity it is necessary to consider the month or seasons sepa- rately and to work out expected conditions for different intensities of solar activity. In regard to the use of the second method, forecasting weather as ordinarily practiced at the present time depends on anticipating for a day or two at a time the drift of weather conditions. Such fore- casts can be improved and extended in time by analyzing weather into waves of different lengths and forecasting the progress of the stronger waves. Even long range forecasts can be made on this basis, as I have demonstrated by actual tests. The third method of forecasting is by means of the periodic vibrations in the sun and atmosphere. Any pulsation in solar condi- tion will be attended by similar pulsations in the earth’s atmosphere. The shorter pulsations will be felt relatively more in high latitudes of the earth and the longer pulsations relatively more at low lati- tudes, but all will be repeated to some extent in every part of the atmosphere. An analysis of the periodic terms in the weather at any point on the earth would make it possible to project the periodic terms ahead to any length of time desired, were there no variations in the amplitude and phase of the periods. But there are variations and for this reason it is necessary to redetermine the periodic terms at short intervals and to limit the time in advance which they are made to cover. When these variations in the periodic terms become calculable, this method of forecasting will probably replace all others. Already considerable progress has been made along this line. In practical forecasting at present it is desirable to consider all of the three methods mentioned and to use them as checks on each other. Forecasting in words has but little meaning to the average expert, because the meanings of words can be interpreted in various senses and there are no accepted rules for verifying such cases. Quantitative forecasts can, however, be verified by accepted stand- ards ; so that from the beginning of my experiments in forecasting, both verbal and quantitative forecasts were made. These quantitative forecasts were made first for about a week in advance, then for longer intervals up to a month. Figure 31 gives one of the more recent of these forecasts of pressure made on November 24, 1929, for 27 days in advance beginning on November 26 and ending on December 21. The forecast was made up from a combination of cycles varying in length from 3 days to 13 days. The correlation of the forecasted with the observed pressure is 0.64 + 0.06. 46 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 By computing pressure in this way for a network of stations, weather maps bearing unmistakable resemblance to observed weather maps may be computed in advance. In March, 1929, values of pres- sure were computed for one week in advance for 23 selected sta- tions forming a net over the United States and from these computed values lines of equal pressure departures were drawn, The maps NOVEMBER, 1929 DECEMBER 2627026029150 Nae SAS 6 BO NOMIIZ Sta IS enim Snl9 scored CHICIA : 4H fis ZAIN ae ai calsT Fic. 31.—8 a. m. pressure. thus forecasted are compared with the observed pressure distribu- tion in figure 32. The close resemblance of the two sets of maps is apparent. This degree of accuracy can be obtained, however, only when the meteorological cycles are comparatively steady. It is never- theless the goal toward which research is leading and to which it will undoubtedly attain. In April, 1929, a diagram was sent to a number of persons, including the Secretary of the Smithsonian Institution, giving a fore- cast of departures from normal temperature by weeks from April 2 to September 3 for New York City and for two other stations. Fig- ure 33 gives a copy of this plot for New York City. The broken curve shows the forecast and the continuous curve shows the ob- served departures from normal. The correlation coefficient for the 23 weeks is 0.37+0.12. This correlation taken alone is inconclusive as to the possibility of such forecasts, except in the light of other data indicating its possibility. It is believed that forecasts by months and years are feasible on the same basis and by the same methods, but no prolonged test is yet available. If the conclusions presented in this paper are verified and accepted by other research workers, as I feel they must be in time, it will NO: 7 THE ATMOSPHERE AND THE SUN—CLAYTON 47 PRESSURE MARCH [3 OBSERVED -—. | aS + ——rr— Fic. 32.—Pressure forecasted from a combination of meteorological cycles. APRIL MAY JUNE JULY AUGUST 2 9. 16.25.50 7 14.21.26 4 W186 25. 2.9 16.25.30 6 15 20 27 3 PPP UN ALALN ALLL 5 = a, \Y/ Ghz S a CUNVETETELL EY TT ) / : / +---~- FORECASTED OBSERVED Fic. 33 Weekly temperatures 1920. 48 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 mean a revolution in present methods of weather forecasting. The forecasting of pressure and temperature will be made in much the same way that ocean tides are now predicted, except that the periods used will be solar periods rather than lunar periods and will need to be treated in a special way owing to changes in phase and amplitude. Such a successful forecast as that shown in figure 31 seems con- clusive evidence that day to day weather is not a haphazard occur- rence as many persons believe, but is subject to calculation. It is evident that changes of pressure are calculable to some extent now, and the calculations will, no doubt, in the future be made with increasing accuracy for weeks and perhaps months in advance. Proc- esses will be simplified and machinery like the tidal machines will be introduced in order to handle the immense amount of data which will be needed for world-wide forecasts, or even for forecasts over a large area like the United States. SUMMARY This paper contains evidence pointing to the following conclusions : Solar activity varies in complicated pulses. These pulses or varia- tions in intensity are attended by variations of pressure in the earth’s atmosphere. When solar activity, as indicated by spots and radia- tion values, increases, the latitude contrasts of pressure in the earth’s atmosphere are increased and atmospheric circulation speeded up. The pressure falls in the equatorial belt, rises in middle latitudes and falls in the polar regions. When solar activity decreases the reverse conditions occur. The zonal regularity of these changes is interfered with by the distribution of land and water and by seasonal changes. Immediately following the decrease of pressure in the polar region with increased solar activity, a wave of decreased pressure moves toward the Equator. With decreased solar activity the pressure in polar latitudes increases and a wave of increased pressure travels towards the Equator. These waves move with a speed proportional to the length of the solar pulse or period causing them. If the period of oscillation is seven days the wave moves from pole to Equator, when measured along a meridian, in seven days. If the length of the oscillation is 27 months, or 24 years, the time of the wave movement from pole to Equator is 27 months and if the length of the period is 74 years the time of movement from pole to Equator is 74 years, or one period of oscillation in each case. NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 49 There are also east to west movements of the waves, and there are probably returning waves toward the poles of less intensity ; so that the observed phenomena are extremely complex. The analyzed wave movements are subject however to apparently simple laws, and can, therefore, probably be computed and combined to produce ob- served conditions. The observed data of sun-spot numbers and solar radiation values when subjected to harmonic analysis for the 11-year period 1917 to 1928 show that the dominating period of about II years in sun spots is no more marked in solar radiation values than the subhar- monics of 4, 4, 4, etc., of the 11-year period which have ampli- tudes nearly as large as the 11-year period itself. When the pressure observations in the Tropics are subjected to harmonic analysis they show periods resembling in amplitude those of solar radiation values and not those of sun spots. The analyses of the data in higher latitudes show that the amplitudes of the subhar- monics increase with latitude, so that in high latitudes in the neigh- borhood of the pole the subharmonics become vastly more important than the primary period. A study of the possibility of analyzing the data at each particular part of the earth with the view to discovering fixed periodic cycles indicates that if such cycles exist, the amplitudes are subject to wide variations and even to inversion of phase from time to time. However, when the complex cycles are analyzed individually and averages taken for a small number of successive cycles, it is possible to project them into the future and combine and plot them in a curve which at times has a striking resemblance to observed data. As knowl- edge of methods and laws of change progress, this kind of fore- casting will undoubtedly be done with increasing accuracy. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 8 FOUR NEW RACCOONS FROM THE KEYS OF SOUTHERN FLORIDA (WiTH Five PLATEs) BY E. W. NELSON (PUBLICATION 3066) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION JULY 10, 1930 ey ys f a an i ny “I eae Ay aad A Sl kil ; ’ : a) if - : oT ie ! i : 7 wy if I The Lord Battimore Press BALTIMORE, MD., U. & Ae : Ne j i . i, e 4 j pe ae AY 4 4 ee ee no FOUR (NEW RACCOONS FROM. THE KEYS OF SOUTHERN FLORIDA By E. W. NELSON (WitH Five Pirates) Between the last of February and late in March, 1930, the author visited the keys lying about the southern end of Florida and collected on them a series of ‘61 specimens of raccoons. The keys, or islands, visited proved to be segregated into four rather well-defined groups and the specimens collected show very definitely that each group is oc- cupied by a subspecies of Procyon lotor peculiar to it, and all differing from Procyon lotor elucus of the neighboring mainland. The main islands of each group are named below but, in addition, each group includes many smaller islets practically all of which are covered with mangroves. Ist. Ten Thousand Islands Group forms a broad compact belt of mangrove keys lying for about I00 miles along the southwestern coast of the peninsula, from a little south of Naples down to Shark River. The width of this belt varies from one to several miles, its exact width and some other details not being as accurate as desirable in published maps I have seen. 2d. Key Largo Group, as here considered, lies along the south- eastern border of the peninsula and includes Virginia and Biscayne Keys just north of the entrance to Biscayne Bay, and Elliott Key, Key Largo, Plantation Key with Upper and Lower Matecumbe Keys to the south of the entrance. 3d. Key Vaca Group lies southwesterly from the preceding group and begins with Long Key on the north and extends south to include Duck, Grassy, and Fat Deer Keys, Key Vaca, and Knights Key. 4th. Big Pine Key Group still farther to the southwest includes No Name, Big and Little Pine Keys, Torch Keys, Ramrod, Cudjoe, Summerland, Saddlebunch, and Boca Chica Keys, and Key West. The isolation of raccoons of the Procyon lotor type in islands on the Atlantic coast side of the continent from Cozumel Island, off the peninsula of Yucatan, to the Bahamas and the coast of southern Florida, has tended toward the production of depauperate forms as all of them are smaller than the animals of the adjacent mainland. On the Pacific side of the continent the raccoons of the Tres Marias SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No.8 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Islands are about the same size as the animals of the neighboring Mexican mainland. These islands are high and wooded and fresh water occurs on them. Conditions are such, on practically all of the keys off the coast of southern Florida, that the raccoons living on them have no access to fresh water beyond the fortuitous opportunities that may occur during a heavy rain. To this circumstance, many of the local trappers believe, is due the smaller size of the animals of the islands, for they say the larger, better furred animal of the mainland occurs where permanent fresh water exists back from the shore. Along the south- western shore of the peninsula these large fresh water “coons”’ are said usually to keep about the fresh water but to come down to the mangrove swamps along shore at certain seasons. The trappers agreed, however, that they never cross to the adjacent keys, even in the Ten Thousand Islands, some of which have only narrow, shallow channels cutting them off from shore. In addition to their tendency to reduction in size the Key raccoons have a distinct tendency toward duller and paler colors than the animals of the mainland. The paleness is especially marked in the forms from the Key Vaca and Big Pine Key Groups. The abundance of crabs, shellfish and other food een by the sea for the raccoons, would appear to remove the possible factor of food shortage from the list of possible causes for the smaller size among these animals, At the same time the absence of natural enemies evidently gives favorable conditions for their increase and the ac- counts given me of the amazing number of them trapped on the keys, when the high prices of furs gave the incentive, make it ap- parent that they must have been excessively numerous for an animal of their size. Under natural conditions in the past, therefore, com- petition for food may have been very strenuous for long periods. On the Ten Thousand Islands some of the trappers told me that when the high prices for fur began single trappers sometimes took the skins of more than 800 raccoons on the keys in a season but that, owing to this severe trapping, it is difficult now for a man to get even one-third of that number. Similar accounts of the former abundance of raccoons on other keys off the coast were given me by trappers elsewhere. Some of the trappers put out more than 100 traps and settings of from 40 to 60 are common. The total catch of raccoons for southern Florida and the keys must be very large. The measurements and weights in the flesh of the series collected by me gave direct evidence that the female raccoons of that region, in the flesh, weigh more than 20 per cent less than the males, and No. 8 NEW RACCOONS FROM FLORIDA—NELSON 3 the more smoothly rounded, smaller skulls of the females give the same evidence. Measurements, weights, and skulls of the series collected by Dr. E. A. Mearns in Polk County, the type region of P. 1. elucus, show similar size differences between the sexes of that form. The study of my series of specimens and comparisons with a large number of specimens of Procyon lotor elucus from the Florida main- land and of representatives of P. maynardi and P. minor from the Bahamas makes it appear that a natural laboratory of evolution is obviously at work on the Florida Keys with the generally distributed and abundant raccoons as, at least, one of the principal subjects. It is a pleasure to acknowledge my indebtedness to Dr. Thomas Barbour and to Mr. H. E. Anthony for the use of material under their charge in the Museum of Comparative Zoology and the American Museum of Natural History, respectively. THE RACCOON OF THE TEN THOUSAND ISLANDS More than two years ago a friend told me that a raccoon smaller than that of the mainland was reported to exist on the chain of keys bordering the southwest coast of Florida, known as the ‘“ Ten Thousand Islands.” This suggestive information was kept in mind and the last of February, 1930, I arrived at Fort Myers, on my way to investigate the rumor. Being delayed there for a day I located a fur buyer and in reply to my inquiries he promptly confirmed the truth of the statement which had caused my quest. He said that.a very small, rather pale colored, raccoon is well known to the trappers and fur buyers of this region, where it occupies the islands, or “ keys ” along the coast. He added that owing to its small size and the inferior quality of its fur “key coon”’ skins bring only about one-half to two- thirds the price paid for the larger, better furred skins from the mainland. The trader then produced about 30 “ key coon” skins from Marco Island, which he had recently purchased, and I was delighted to note their distinctive peculiarities. The next morning I proceeded by rail to Marco Island, one of the larger of the Ten Thousand Islands, near the northern end of the group. It is several miles in both length and breadth and is bordered by a belt of mangrove swamp where the raccoons live. The interior is sandy, several feet above high tide mark, and covered with a thin forest of scrubby, slender pines with scattered undergrowth. Soon after my arrival I found resident trappers who agreed that “key coons’’ were common on the island, but that those found on the keys near Chokoloskee Bay farther south were the smallest of all. 4. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Desiring to secure the most marked expression of this scientifically unknown form, I left Marco Island at once and proceeded by auto- stage to the town of Everglades, located about the middle of the east side of Chokoloskee Bay. The next morning I went to the fishing village of Chokoloskee, near the southern end of the bay, where a trapper with a small motor boat was employed and at the expiration of about ten days we had a series of 16 specimens, all taken on the small mangrove keys lying between Chokoloskee Bay and the open waters of the Gulf of Mexico. The delay in getting these animals was due to the fact that I had arrived at the end of the trapping season and the number left was comparatively small. Previously I had always thought of raccoons as animals dependent on available fresh water and it surprised me to find them living in great numbers among the mangrove islands, both in the Ten Thousand Islands and on other Florida keys, without any possible source of © such water. Their food consisted of an abundant supply of fish, crustaceans, and shellfish left exposed on the mud at each low tide. The haunts of the raccoons among the mangrove roots of the Ten Thousand Islands were shared by great numbers of roof rats (Rattus rattus alexandrinus). These were so numerous that they interfered with our success in trapping the raccoons, dozens of them being caught. Another interference was the frequency with which fish and crabs ate the bait above the traps while they were submerged during high tide. As a result of these marine visitants the traps sometimes capture curious prey. Several kinds of fish and crabs, in wallowing about when tugging at the bait, now and then spring the trap and are caught. My trapper said that on one occasion he caught a small shark about 18 inches long. His method of trapping, which he in- formed me was the regular practice among these keys, was to make a little U-shaped enclosure by sticking pieces of dead mangrove roots into the mud in a small opening among the mangrove roots at the head of small bay-like indentations of the shore line, where the animals patrolling the bare mud at low tide would find it on their way from point to point. A piece of fish for bait was impaled on a small stick, the other end being stuck in the mud at the inner part of the enclosure. The steel trap was then set on the bare mud at the entrance of the enclosure guarding the bait, without the slightest effort to conceal it—a stick thrust through the ring at the end of the chain and deep in the mud serving to hold any animal caught (see pl. 1, fig. 2). At high tide this trap would be more than two feet under water. Trapping among these keys is practically all done by using small boats with outboard motors, or small gasoline engines. No. 8 NEW RACCOONS FROM FLORIDA—-NELSON 5 The common name for this group well indicates the great number of little keys of which it is formed. They are closely grouped and of - most irregular outlines, being separated from one another, and from the mainland, by a network of tortuous, shallow tide channels varying in width from a few yards to several hundred yards. Enclosed within this mass lie Chokoloskee and other narrow land locked bays. Cho- koloskee Bay is the largest, having a length of about eight miles and a width of from a half mile to a mile and a half. Nearly all the keys of the group, like those where we trapped the raccoons, are overgrown with tangled masses of the aerial roots of the red man- grove above which rises the low wall of their dense, green tops. These keys, in general, are covered with from one to about three feet of salt water at the daily high tide and are devoid of fresh water. The Ten Thousand Islands form, in fact, a great mangrove swamp based mainly on the flat tops of old oyster beds. The red mangrove thickets rise about 25 feet and are interspersed with larger black mangroves and a few other salt loving small trees or bushes. In the Shark River section, to the south, the mangroves are the largest I have ever seen, forming closely set forests of trees 40 to more than 60 feet high. The mainland adjacent to these keys is bordered by a fringe of mangrove swamps limited by the end of salt water. The accompanying photograph gives an idea of the typical water front of the mangrove islets near Chokoloskee (see pl. 1, fig. 1). I have included the mangrove keys of the Shark River area within the range of the small Chokoloskee raccoon wholly on statements of several trappers that the raccoons there are the same as those about Chokoloskee Bay. No specimens have been seen from there but several from the mainland a few miles away at Cape Sable and Flam- ingo are unmistakably P. 1. elucus. RACCOONS AND THE FLORIDA KEYS After observing the effect of environment on the raccoons of the “Ten Thousand Islands ” it appeared probable that similar influences may have produced modifications of the animals living on the great series of islands or “keys” extending from Biscayne Bay to Key West, commonly known as the Florida Keys. To determine the facts concerning this I crossed the Everglades, over the motor highway, from the town of Everglades to Miami. There, through the friendly assistance of Mr. E. J. Brown, some trappers were promptly located who were well acquainted with all the keys. The information they gave confirmed my belief that the raccoons there would differ from those of the mainland. Two trappers were employed as field assistants 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 and by the use of motor boats and an automobile we made a rapid reconnaissance of the entire chain of keys to Key West. Raccoons occur abundantly on all the keys and we obtained a sufficient series to indicate their characteristics. As at the Ten Thousand Islands this work was done soon after the close of the regular trapping season, during which thousands of raccoons had been caught, so that much more time was required to capture the animals needed than would have been necessary earlier in the year. These keys are connected by the Over-Seas Railway from Miami uniting them by fills where the channels are narrow and shallow and by cement viaducts and bridges where they are more broadly and deeply separated. In recent years the Over-Seas motor highway has been constructed parallel to the railway from Miami, striking the middle of Key Largo and extending thence down the keys to the southern point of Lower Matecumbe, whence a ferry carries passengers and motor cars across about 40 miles of water to the northern end of No Name Key. There the motor road begins again and continues southward crossing various keys to Key West. In addition to the railway fills which unite some of the keys in this chain, other fills made for the highway broaden the land bridge made by the railway embankments uniting a number of keys, thus destroying their individuality. About midway in the 40-mile gap between the northern and southern groups of keys lies a smaller group, the main one of which is Key Vaca. A practically disused motor highway, extending north and south about 12 miles, joins the main keys of this group except Long Key which lies isolated by sea channels nearly midway between Key Vaca and Lower Matecumbe. As shown below, the raccoons living on each of these natural groups of keys, the northern, the middle, and the southern, has its local subspecies. The Florida Keys differ very much in formation and vegetation from the Ten Thousand Islands. Most of these keys, except the more recent small ones, are of limestone with nearly level surfaces, elevated well above tide water, with borders of varying width of mangrove swamp which are covered at high tide. Back of the tidal area on the Key Largo and Key Vaca Groups is a strong growth of deciduous tropical shrubs and trees often forming a dense and al- most impenetrable jungle, from 15 to 30 feet high, where it has not been destroyed by man. The northern half of Key Largo has the heaviest forest growth I saw on the keys, rising to 50 or 75 feet high, or perhaps more, in places. The trees appear to be the same species as those elsewhere but grow on a better soil. Roe a Ae ae No. 8 NEW RACCOONS FROM FLORIDA—NELSON 7 The western, or Gulf, shores of all the large keys are bordered by a practically continuous fringe of mangrove swamp but on the Atlantic side occur sandy beaches often bordered by irregular series of coconut palms, while scattered fan palms, often with trunks ten to more than 25 feet long, are generally distributed in the interior. A large part of Big Pine Key is covered with a thin growth of slender dwarfed pines and palmettos with scattered areas of deciduous trees and bushes. The neighboring Little Pine, No Name, Torch, and Ramrod Keys have smaller areas of pine forest. The interior of the other keys to Key West have the deciduous species common to the entire chain of keys, with the usual marginal mangrove swamps and occasional sand beaches. The trappers informed me that the raccoons of the Florida Keys go back inland from the mangrove swamps, where they generally live, to feed on any ripening fruit that occurs. At the time of my visit to Key Largo, a shrub about three feet high was laden with clusters of dark fruit appearing, in color and shape, like huckle- berries. Raccoons were feeding extensively on it. PROCYON LOTOR MARINUS subsp. nov. Chokoloskee Raccoon Type—From near Chokoloskee, Florida. No. 254989, J adult, U. S. National Museum, collected by E. W. Nelson, February 28, 1930. General characters ——A very small subspecies, the largest old male in the series taken weighing 8 pounds. Duller grayish than P. /. elucus, of adjacent mainland, with skull much smaller, more depressed on frontal area and molariform teeth proportionately much heavier. Color.—Not very different from typical elucus but averaging duller, more grayish on upperparts owing to smaller amount of black tips to overlying hairs; rusty buffy nape patch averaging less strongly marked, often obsolescent ; light rings on tail paler, less buffy yellow- ish; black mask more restricted with remainder of top and sides of head paler. No indication of the generally rusty or dark buffy suf- fusion covering entire upperparts frequently present, and sometimes strongly marked, in specimens of elucus from the type region. Skull—Much smaller and more delicately proportioned than in elucus; frontal area much more depressed, braincase more rounded ; last upper premolar and carnassial relatively, and sometimes actually, larger ; palatal shelf about the same. 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS. VOL. 82 Measurements——Type: Total length, 665 mm.; tail vertebrae, 222; hind foot, 105. Skull (type): Greatest length, 105.9; condylo- basal length, 101.8; zygomatic breadth, 64.8; interorbital breadth, 22.3; least width of palatal shelf (between last molar and interptery- goid fossa), 13.9; upper canine-molariform tooth row (alveolar length), 40; weight of type in flesh, 7 pounds. See page 12 for tables of measurements and weights. Remarks.—This is one of the smaller subspecies of raccoons that have developed on the keys about the southern end of the peninsula of Florida, not differing much in size from the form on the Key Vaca Group. It appears to be limited to the great mass of mangrove covered or bordered islands, or keys, known as the “ Ten Thousand Islands ” where they exist in great numbers. Most of these islets are completely covered by the sea to a depth of from about one to three feet at each high tide, and are totally devoid of fresh water. As most of these keys have no large trees to afford hollows and no dry land the raccoons must make their homes on top of the mangrove roots where they are forced to retreat by the incoming tide. Specimens examined—t17: from type locality, 16; from Ten Thousand Islands (exact locality unknown), 1. PROCYON LOTOR INESPERATUS subsp. nov. Matecumbe Raccoon Type.—From Upper Matecumbe Key, Florida. No. 255037, J adult, U. S. National Museum, collected by E. W. Nelson, March 19, 1930. General characters—In weight and color resembling typical P. 1. elucus of adjacent mainland but both body and skull measurements smaller, especially length of hind foot; frontal area of skull much more depressed. Color—Much as in typical elucus, strongly washed with black on upperparts and well marked nuchal patch of dark rusty or buffy, dark rings on tail well marked and light rings often strongly buffy. Skull—Differs from that of elucus in smaller size and marked depression of frontal area. From P. /. marinus skull may be distin- guished by its much larger size, more massive proportions and smaller molariform teeth. Measurements—T ype: Total length, 730 mm.; tail vertebrae, 250; hind foot, 115. Skull (type); Greatest length, 110.4; condylobasal length, 108.1; zygomatic breadth, 68.2; interorbital breadth, 23.1 ; least width palatal shelf, 15.2; upper canine-molariform tooth row, 41. Weight of type in the flesh, 8.5 pounds. See page 12 for tables of measurements. No. 8 NEW RACCOONS FROM FLORIDA—NELSON 9 Remarks.—The present subspecies occupies the group of keys be- ginning with Virginia and Biscayne Keys on the north side of the entrance to Biscayne Bay and ranges south to the southern point of Lower Matecumbe Key. Key Largo, the median island, is by far the largest of this group and broad mangrove swamps bordering its western side extend out, about the middle of its length, until only a comparatively narrow channel separates them from the similar swamps which extend eastward from the mainland, at the south end of Biscayne Bay. The railroad and motor highway fills, and viaducts extend across these swamps, from Miami to the middle of Key Largo on their way down the keys to Key West. The comparatively short distance separating the raccoons living on these keys from those of the adjacent mainland, with the size and color of the island animals, made me doubt any strong differentiation when I was collecting them. Fortunately I was able to secure two good males and a female on the adjacent shore of the mainland to determine the question. The skulls of these specimens are typical P. 1. elucus, with characteristic high arched frontal areas from which all the skulls of the series from the various keys of this group may at once be distinguished by their appreciable smaller size and more flattened frontals. The largest male taken on Key Largo weighed 12 pounds in the flesh, the same as old males collected and weighed by Dr. E. A. Mearns in Polk County, the home of typical elucus, but the skull of the present form is smaller and flatter. It may be added also that specimens taken on Upper Matecumbe and especially those from Lower Matecumbe Key, the farthest point in the group from the mainland, show gradation toward a smaller animal than those of Virginia Key and Key Largo. Specimens examined.—15, all from the Key Largo Group, as follows: Virginia Key, 2; Key Largo, 3; Plantation Key, 2; Upper Matecumbe Key, 1; Lower Matecumbe Key, 7. PROCYON LOTOR AUSPICATUS subsp. nov. Key Vaca Raccoon Type.——From Marathon, Key Vaca, Florida. No. 255080, ¢ adult, U.S. National Museum, collected by E. W. Nelson, March 28, 1930. General characters—Very small, about the same size as marinus from which it may be distinguished by its grayer upperparts, more brownish yellow pale rings on tail, more depressed frontal area on skull and shorter palatal shelf. Its small size distinguishes it at once from the other forms described here from the Florida Keys. Io SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Color.—General coloration rather paler grayish than in marinus with tendency to a smaller black mask and more whitish head, rusty nape patch brighter, light rings on tail broader, more brownish buffy, black rings relatively narrower. Skull——Similar in its delicate proportions to that of marinus but more flattened over frontal area, braincase more rounded, and palatal shelf shorter. Measurements —Type: Total length, 644 mm. ; tail vertebrae, 214; hind foot, 99. Skull (type): Greatest length, 99.8; condylobasal length, 95.5 ; zygomatic breadth, 65.5 ; interorbital breadth, 19.4; least width palatal shelf, 13.9; upper canine-molariform tooth row, 37.4; weight of type in the flesh, 5.5 pounds. See page 12 for tables of mea- surements and weights. Remarks.—The small raccoon from the Key Vaca group in con- nection with other raccoons of Florida requires comparison only with P. 1. marinus. It is abundant in the mangrove swamps of Key Vaca and the immediately adjacent keys. The range occupied by the Key Vaca raccoon is the smallest and most compact of that of any of the forms I found among the keys. Specimens examined.—13, all from type locality. PROCYON LOTOR INCAUTUS subsp. nov. Torch Key Raccoon Type—From Torch Key, Big Pine Key Group, Florida. No. 255000, ¢' adult, U. S. National Museum, collected by E. W. Nelson, March 24, 1930. General characters—Slightly smaller than inesperatus, upperparts palest, most dingy gray of any of the forms described here; skull comparatively narrow interorbitally with elevated frontal area more like elucus than in the other key forms described here. Color.—The palest gray of the key raccoons, black mask more restricted, sometimes obsolescent, and elsewhere top and sides of head whiter ; pale rings on tail broader, dark ones narrower and usually dusky brown; rusty rufous nape patch usually present and sometimes strongly marked. As the season advances the colors commonly bleach until many are wholly dirty yellowish or dingy whitish. Skull.—Differs from other key forms described here by greater interorbital compression and distinctly more highly arched frontal area, resembling that of elucus but less strongly arched ; zygomatic breadth widest of the key forms; molariform teeth smaller propor- tionately. No. 8 NEW RACCOONS FROM FLORIDA—NELSON II Measurements —T ype: Total length, 694 mm. ; tail vertebrae, 263 ; hind foot, 218. Skull (type): Greatest length, 110; condylobasal length, 105.3; zygomatic breadth, 67.3; interorbital breadth, 19.8; least width palatal shelf, 15.1; upper canine-molariform tooth row, 38.8 ; weight of type, 8.5 pounds. See page 12 for tables of measure- ments and weights. Remarks.—The home of this form of raccoon is on the group of Florida keys farthest from the mainland. As in the case of the other forms described here they live mainly, and sometimes entirely, in mangrove swamps without access to fresh water except during rains. The brilliant light of their environment has affected their general color more than in the others, as shown by their pale, faded tints. Specimens examined.—z20, all from the keys of the Big Pine Group, as follows: No Name Key, 5; Big Pine Key, 6; Torch Key, 2 (type locality) ; Ramrod Key, 1; Boca Chica Key, 2; Stock Island 2; Key West, 1. n oo) | ) > SMITHSONIAN MISCELLANEOUS COLLECTIONS [2 (z'ob-1°g) £°6F (6£-1°Z£) OLE (tzb-6£) Ib (€:0b-g£) 2°6e (L-bb-gzb) Ler (1'91-G°E1) OVI Gif) vr (1'gt-2°S1) BieaiD (1'S1-6°E1) EVI (€°21-ST) 2°91 (9°€z-9'61) Siz (F0z-g'gl) oz (gbz-S'1z) 2 (6°€z-9'°61) 1°1z (Sz-z°€z) 6&2 (g4-F'z9) 1°69 (1°99-09) 4°£9 (622-9) S*L9 (9°69-1'6S) &°F9 (g'94-24Z) ShZ (1'901-g'46) £01 (1'10I-g°£6) 9°96 (1°gOrI-00r) 1°Sor (g°101-£6) 6°96 (S*2Zr1r-E"Err) 2Srx (¥11-9'bor1) £601 (901-666) Z*101 (vort-z'Sor) S:gor (6°So1-9°46) g°zor (g°zz1-6°Z11) £:ozt Ceara nC nana) (Aq1] 290] ad} Surpnyour) shay jo dnoiy osulg 31g ‘SnqnvIUL 4040] UOkIOAG SDUTOC hye) claim) eoeA Aay ‘uo yee py ‘SNJDILGSND 4040] UOKIOAQ (ATT BOOT Oday Suipnpour) shay jo dnoir) os1e7] Aay ‘sng -pAagSaut 4030] UOXI0AG Cee eee ee tens (Aqtyeo -o[ 3dA}) saysojoyoy) ‘snuaiput 4030] UokI04g *(qeo1d}) Ayunog yog ‘snInja 4030] UOkKI0AT S9U9.1}X9I—MOI y}00} UtOFLIejOUr -sulueo saddy souiot}xo —yJeys jeqyeyed WIpIM 4sea'y elite eb e) —y}e2.14q [edgqso19qu] soWaijxo —yypre1q dIFEWIOSAT SoW191}x3—]}.SUs| [eseqo;Apuo) SoUI91}XO —Y}8u3] 4So}eaI14 sugutoads HON OIN| Sal}I]Booy, pue sa1oadsqns jo sawieyy SINGNAINSVAYP, TIONS DVAHAY AO ATAVT AAILVYVdWO-) VdINOTA NYAHLNOS AO SAUM AGNV WINSNINAd AHL WOU SNOODOVA P LINdGV (3°g-4) 1°8 (9-S) 9°S (z1-$2°2) g9°6 (8-9) 89°9 (ZI-O1) II SOUI9I}X9 —spunod UT JYSIO MA (QII-gor) € (401-26) 1o1 (vz1-E01) L411 (Sor-S6) ror (6z1-Sz1) £z1 So9WlI1}xXI—}OO} pury jo yyBua7] (g4z-91z) bSz (SZz-viz) S&z (zSz-0zz) gz (Zzz-9gZ1) goz (Ogz-oFz) 192 SQUuiat}X9 —2PIGa}IOA Te} JO YpBuaT SoWotj}xXa —Y}suyg] [e}0L, nn Suypnjou!) eka, jo dnoin fay aulg sig SCAR TEOO} adAj) eoeA Ady GOqese ‘snyooudsnv 4040] UOKIOAY (Aqpeo0] ad Ay ‘SNINDIWA AOJO] UOKIOAT sets (Aqrpesoy adAy Burpnjou) sAay jo dnoin osiey Aoy ewelegeae 4040] UOKIOL tN russes (Aqtpeoo, adAz) daxsojoyoyD ‘snuimut 4030] UOKIOAG (jeo1dé}) Ayunoy ylog ‘snanja 4040] uokI04q suauttoads jO ‘ON SOI}IPLIO] pue seiosadsqns jo sowey HSaTY AHL NI SLHOIGM GNV SINANAYNSVAJ ADVUHAY AO ATAV]T, AAILVAVdINO?) VdId¥OTA NYAHLNOS AO SAUM GNV VINSNINUd AHL WOUA SNOODOVA PF LINdGV ‘Of61 ‘yore Ul AVG ddysojOYoyD Jo }saM Jost UO Suljjas W “ye ay} St Yoeq ye YS uo ysy jo ssid ayy oy} ‘suooasei Joy Sutuado ze yas se uorrsod ur deaz YyYM pnw ur Yonjs s}oor aAorsueu Jo ape usd padeys-Fy %YL—ze “OY “SNULADUL 4010] UokI04g JO yUNLY [edd] ay} SI ST, “"pataAod aie aiay pasodxa s}oos ay} Jo FEY Joe apy Yory ye pue ported st pntu oy} ap. MOT FY ‘OPH Fey ye ‘Vpl4opy ussjsomyNoS ‘Keg saYsSojOYOYD JO }SaM Jo]S! UO $}OO1 [eLIIe JO T9AOS dAOISULIN—'I “DI ll mers aay Lt 14 '@ "ON '278 “210A |. SNOILO31100 SNOSNVTIISOSIN NVINOSHLINS SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82, NO. 8, PL. Z. Fic. 1.—Procyon lotor clucus, 3, typical skull, Polk County, Florida. Fic. 2.—Procyon lotor inesperatus, 3, type skull, Upper Matecumbe Key, Florida. Skulls natural size. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLE. 82; NO:-8),.PE. 3 2. Fic. 1—Procyon lotor auspicatus, 3, type skull, Marathon, Key Vaca, Florida. Fic. 2—Procyon lotor incautus, 3, type skull, Torch Key, Florida. Skulls natural size. The subspecies reproduced in plates 2 and 3 follow in the geographic sequence of their occurrence from P. /. elucus of the mainland down the three groups of the Florida Keys. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL; 182, INO: <8, (PEas4: Fic. 1.—Procyon lotor elucus, 3, typical skull, Polk County, Florida. Fig. 2—Procyon lotor inesperatus, 3, type skull, Upper Matecumbe Key, Florida. Skulls natural size. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOENS 2; a NO mone Leno Fic. 1—Procyon lotor auspicatus, 3, type skull, Marathon, Key Vaca, Florida. Fic. 2.—Procyon lotor incaulus, 3, type skull, Torch Key, Florida. Skulls natural size. Subspecies reproduced in plates 4 and 5 follow in their geographic sequence as in plates 2 and 3. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 9 THE FURTHER AND FINAL RESEARCHES OF JOSEPH JACKSON LISTER UPON THE REPRO- DUCMIVE: PROCESSES OF POLYSTOMELLA CRISPA (LINNE) (An Unpublished Paper Completed and Edited from His Note-Books) (WITH SEVEN PLATES) BY EDWARD HERON-ALLEN, F.R.S. (PUBLICATION 3067) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION NOVEMBER 26, 1930 ty) iy i nf oI ps p ¥ ; al 1 ; i all Anas, care ; : te ; ivy @ ; ; > : ’ 1 a 7 . + . ~ . a i) | hw | \ } 1 , The Lord Baltimore Press BALTIMORE, MD., U. 8. A. fot PURTHER AND FINAL RESEARCHES OF JOSEPH JACKSON LISTER UPON THE REPRODUCTIVE PROCESSES OF POLYSTOMELLA CRISPA (LINNE) (An Unpublished Paper Completed and Edited from His Note-Books) By EDWARD HERON-ALLEN, F.R.S. (WitH SEVEN PLaTEs) INTRODUCTORY NOTE For over 30 years Lister’s work upon the reproductive processes of the megalospheric form of Polystomella crispa (Linn.) by means of flagellispores has been familiar to protozoologists, and especially to students, both in text-books and in the lectures of university pro- fessors, and it recurs incessantly in examination papers. For over 30 years it has been well known that his equally, if not more, impor- tant work on the reproductive processes of the microspheric form by what may not improperly be called viviparity had been completed, but with the exception of the short postscript to his paper published in 1895 it has not been available to protozoologists. The reason for this is difficult to fathom for anyone who did not know him inti- mately. We know that his nervous sensibility was such as to reach at times a pathological condition, and he could never be persuaded to publish anything that he took it into his head to keep to himself. I suppose that, so far as the Foraminifera were concerned, I was his most intimate friend and fellow-worker, but, though we frequently visited each other and continually corresponded, he never showed me any of these preparations, photographs, or lantern slides. I esteemed it therefore as a great privilege that I was allowed, after his death, to sort and arrange the whole of his microscopical materials and preparations, and the papers and note-books relating to them, and having found the whole of his material, his slides and his own unpublished paper upon it, I was permitted by the late Mrs. Lister, herself a noteworthy zoologist, to give to the world of science the information that it had been awaiting for 30 years. When the last and the youngest of the men that he taught have died; when the problems attaching to Astroclera have been solved ; SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 9 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 when his teaching in the Zoological Schools of Cambridge have be- come a mere tradition; when his patient, laborious work upon the geology, ethnology, and ornithology of the South Seas has become - but a brick in the vast edifice of human knowledge; indeed so long as men shall devote labor and research to the science of protozoology, the name of Joseph Jackson Lister, like that of his illustrious uncle, Lord Lister, and of Harvey, Jenner, Leeuwenhoek, Redi, and Schwann, will live in the hearts and on the lips of men, and the dis- covery which will spring to the mind when his name is mentioned will be that of the reproductive processes of the reticularian Rhizopods, especially those of Polystomella, and the meaning and significance of dimorphism. Those of us who were privileged to know him, and especially those of us who in our researches have followed in his footsteps, know how delicate and polite was his use of the results of his amazing industry, patience, and almost universal interests—industry and interests pursued and recorded indefatigably in the face of physi- cal difficulties beneath which a lesser man would have early succumbed. How much more profound must be the appreciation of one who, like myself, has been privileged to examine his laboratory note-books and the mass of valuable papers that he left behind him at his early death—left in a condition of such exquisite perfection that the ex- aminer is never once checked by the reflection: “‘ If only he were here to explain exactly what he meant by that.” I should hesitate, for fear of being accused of extravagance of speech, to describe the note-books of Lister, were it not that they lie before me as I write and that Mrs. Lister has presented them to form part of the Heron-Allen and Earland library and collections at the Natural History Museum (London), where they will be always available, for the instruction and emulation of future generations of protozoologists. He made notes, not merely for his own use in the kind of persona] cryptogram which we are all apt to adopt in recording our own observations, but for the guidance of any research-workers that should come after him. Every sketch or drawing that he made was as highly finished as though it had been prepared for publication, and the systematic dating of his notes enables us to follow his work step by step, and, for practically the whole of his working life, day by day. It was in the course of the examination that I have been privi- leged to make, that I came across his own manuscript record of his work at Plymouth, extending from June 1 to August 9, 1894, a NO. RESEARCHES OF JOSEPH JACKSON LISTER—HERON-ALLEN J record of such vital interest and importance that no apology is needed for publishing it in extenso. It is the record of his observations upon the reproductive processes of the microspheric form of Polystomella crispa (Linn.), and I have been able to compare this manuscript with his original laboratory note-books, and with the records of his later work in 1895, and in 1904-5. Lister’s researches upon this organism appear to have commenced in March-May, 1893, and it was during this period that he observed the reproductive processes of the megalospheric form by means of flagellispores, which observations he recorded, with a masterly study of the dimorphism and nuclear conditions of the species, in his world- famous paper read in June, 1894, and published in the Philosophical Transactions of the Royal Society of Great Britain in 1895." By one of those coincidences that are curiously far from uncommon in science, Fritz Schaudinn was pursuing an identical line of inquiry at the same time, and the same results were arrived at and published almost simultaneously by both of these great men though working quite independently and unknown to each other.” But when Lister’s Philosophical Transactions paper was virtually on the press, or at least awaiting publication, he was again at Plym- outh, checking his former observations, and making further dis- coveries which may well be described as epoch-making. Let him tell us the story in his own words, ‘but first let us consider for a moment the organisms in question: they are: (a). Polystomella crispa (Linn.): one of the commonest known species, and one of practically world-wide distribution. (b). Polystomella macella (Fichtel & Moll) : a depressed and closely allied species, found associated with P. crispa but somewhat rarer north and south of the sub-tropical areas. I have recorded it myself from Selsey, Torbay, Clare Island, Galway, St. Mawes, and St. Andrews and the North Sea, so it may well have been among Lister’s material: he had no time to be an accurate systematist. Lister does not seem to have recorded observations upon (c). Polystomella striato-punctata (Fichtel & Moll) until 1904. He was again at Plymouth in June-July, 1904, as he says in his note-book, “ hoping to maké some progress in the life-history of the Foramini- fera.” He records his observations upon the reproduction of the * Lister, J. J., Contributions to the life-history of the Foraminifera. Phil. Trans., Vol. 186 B., p. 401, 1895. * Schaudinn, F., Die Fortpflanzung der Foraminiferen und eine neue Art der Kernvermehrung. Biol. Centralbl., Bd. 14, No. 4, February, 1894. 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 megalospheric form of P. striato-punctata by flagellispores on June 29 and July 1. There is no mention of the reproduction of the micro- spheric form by the processes we are now describing, though it is of world-wide distribution, and nearly always found with P. crispa, and it was the first Foraminifer ever figured—by Hooke in 1665 * and by Leeuwenhoek in 1702.” He was there again in the same months in 1905, but added nothing of moment to his previous records, but records the fact that in several of his dishes left behind in 1904, Foraminifera and other organisms were still alive. He printed a highly condensed abstract of these later observations as a postscript, dated August 3, 1894, to his Philosophical Transactions paper, and this postscript, slightly elaborated, appears im this still contracted form in his later works, viz: in Lankester’s Treatise on Zoology in 1903, his address as president of Section D at the York Meeting of the British Association in 1906, and in his Evening Dis- course at the Royal Institution in 1907.” But, for some reason which we shall never know, but which was doubtless connected with his state of health, he never published his paper. No apology is needed therefore for giving to the scientific world his own description of his researches, and their results. It is as follows: ° LISTERS NOLES July 7, 1894. Plymouth—For the last three weeks or so, I have kept Polystomella in tall glass jars,’ the water in which has been renewed frequently by a jet playing through a muslin cover over the mouth of the jar“. The Polystomellas crawl up the sides from the * Hooke, R., Micrographia, p. 80, pl. v, fig. x, London, 1665. *Van Leeuwenhoek, A., Sevende Verfolg der Brieven, etc., p. 105, pl. (opp. PTOL) patio NGO RGD .elitmm7O2: * Lister, J. J.. The Protozoa, Sect. 1. The Foraminifera, in E. Ray Lankester “A treatise on zoology,” Pt. 1, 2nd Fasc., pp. 47-149, 1903. * Lister, J. J., The life history of the Foraminifera. Brit. Assoc., York, 1906, Section D, Presidential Address. *Lister, J J., The Foraminifera. Proc. Roy. Inst. Great Britain, Evening Meeting, February 15, 1907, p. 489, London, 1900. “T have carefully compared this manuscript statement with Lister’s laboratory note-books, and the further details to be derived from these are of such value that I have transcribed such parts of his notes as bear upon his statement, in the foot-notes. *The Polystomella were dredged in 5 fms. on Zostera grass, inside Drake Island in Plymouth Sound, and the experiments commenced on June 17. * When this spraying was not in progress the jars stood on the sill of a window in the sun. J. J. L. ae NO. 9 RESEARCHES OF JOSEPH JACKSON LISTER—-HERON-ALLEN 5 bottom and may be clearly seen when in bright light, with a black background. Usually one or two of the terminal chambers contain little protoplasm and appear empty. In the ordinary condition their pseudopodia are inconspicuous, but they may generally be detected with a pocket lens, extending in sheaves from the shell,” and with a microscope they have the usual appearance of delicate straight threads with granules. In some 50 cases I have seen examples in the reproductive phase. The first sign of this phase is seen in the character of the pseudopodia.” Instead of being disposed as above described, the pseudopodia are limited to a circular or oval area immediately about the shell, the center of the area being the mouth of the shell, which is nearly always flat against the glass. This area is covered completely by a close web of radiating and interlacing pseudopodia, and its limits are fairly sharply defined. The pseudopodia are so thick as to intercept the light, giving rise to the appearance of a semi-transparent milky halo about the shell. This may be called the “ premonitory halo.” It is readily seen by the naked eye. The animals are generally found in this condition in the early morning. In nearly all the cases that I have observed the halo has been established by 6: 30 a.m.” After the animal has remained in this condition for some hours, the protoplasm begins to leave the shell, the strands of the pseudopodia, especially the radiating ones, become thicker, and the protoplasm withdraws itself, first from the peripheral ends of the outer whorl of chambers, being massed in the terminal chambers. Gradually the pro- toplasm leaves the shell, passing through the direct communications between the chambers, and also, as is seen in specimens preserved at this stage, through the canals which exist in the walls separating the chambers from one another. The protoplasm is generally brown, owing to the presence of brown granules.” As the protoplasm emerges into the area of the halo, this becomes streaked with brown, at first in *When they are observed immediately after the jet of water has been playing into the jar, a long sheaf of the pseudopodia is seen pointing towards the current set up in the water. After the water has become still, they are shorter and point in various directions. J. J. L. * This was first observed on June 21, 10: 30 a. m. * While these observations were in progress, Lister frequently remained all night in the Laboratory of the Marine Biological Association. palate Til. 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 thin radiating streaks, which become thicker and fuse with one another until the area is, to a greater or less extent, filled with the dark brown mass.” Specimens which are removed from the wall of the jar while surrounded by the premonitory halo, and placed on cover-slips with a small drop of water, will generally send out fresh pseudopodia and attach themselves to the cover-slip. They may then be placed over holes in filter paper through which a current of water flows, and the hole be completely filled with water. In this way the animal is im- mersed in circulating water. In some cases the pseudopodia thrown out are of the short reticulated character of those forming the halo, and these indicate that the process is going on uninterruptedly ; but it frequently happens that though the animal attaches itself to the glass, the pseudopodia are of the long, little anastomosing character of the ordinary condition. In this case the protoplasm remains in the shell— the animal having, owing to the disturbance, returned to the ordinary state. If however the reproductive phase is continued, the process may be observed under the microscope. When the protoplasm has emerged from the shell, the whole mass undergoes amoeboid changes of shape, and under the microscope may be seen to be in a turmoil of movement,’ the protoplasm coursing along in broad interlacing streams. The streams may be seen to pursue a definite course, the protoplasm in any one part of the mass moving in the same direction for many minutes without interruption. When newly emerged, the brown granules are uniformly scattered through the protoplasm. Gradually a mottled arrangement is pro- duced owing to the appearance of clear spaces (regions) free from brown granules. As the process continues these clear spaces (regions) become larger and more defined, and they are then seen to be more stationary than the remainder of the protoplasm, the streams of granules flowing past them. They are not however entirely stationary. In one instance the area free from brown granules first became evident one and a half hours after the protoplasm had emerged from the shell. Gradually the streaming movements of the protoplasm become less, as the clear regions attain greater prominence, and in about half an hour after their appearance the whole mass becomes broken up into lS Spent: 2 The mass which is at first diffuse, gradually draws together into a more compact mass, the pseudopodia being almost entirely withdrawn leaving branch- ing lines of fine granules marking the positions they had occupied. J. J. L. *230) p.) tt: NO. Q RESEARCHES OF JOSEPH JACKSON LISTER—HERON-ALLEN a rounded spheres, some 50 p» in diameter, whose center consists of clear granular protoplasm (in which I thought I detected a radiate arrangement) the peripheral part being dark with the coarse brown granules.’ In some cases part of the protoplasm remains in the terminal chambers of the shell and divides into spheres in this position. This, however, is not usual. The spheres form at first a compact mass. Shortly, each becomes surrounded by a close felt of very delicate anastomosing pseudopodia, which when seen with a simple lens has the appearance of a mass of white granules * and I supposed at first that a deposit of lime granules had taken place about the group of spheres. They gradually draw apart from one another, so that each can be seen as a distinctly iso- lated mass. : I have killed and stained a number of specimens at different stages of this process. Those in the stage before the protoplasm has left the shell, as well as those at the beginning of the later stage, have the central chambers still filled with protoplasm. In all these specimens it is obvious that it is a muicrospheric individual that is undergoing the process. Again, the specimens mentioned above which, having shown a “ premonitory halo,” returned to the vegetative condition, on being removed to a cover-slip, are found on being decalcified and stained, to belong also to the microspheric form. Altogether I sup- pose I have some I5 specimens whose central chambers are still filled with protoplasm and hence furnished evidence as to the form to which they belong. In a batch of specimens of Polystomella (some 200-odd) megalo- spheric and microspheric specimens were nine to one. This is good evidence that the reproductive phase I am dealing with is that of the microspheric form. The specimens killed in the first stage present, when stained, the appearance I have often seen, the many nuclei being of irregular shapes, and surrounded by numbers of “ stained strands.” In some cases no definite nuclei can be detected, and only few of the strands. When nuclei are present they do not extend into the terminal chambers of the shells. In specimens whose protoplasm has begun to emerge, faintly stained round nuclei 10 » in diameter are found in the clear protoplasm of the terminal chambers, while the innermost protoplasm still has the diffused flush and contains strands of stained matter. *2:40 p.m. Sas 300). mm. 8 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 In some cases the protoplasm immediately surrounding these nuclei has a yellowish red color, as though, perhaps, it contained material which was passing in towards the nucleus. The nuclei 10 p» in di- ameter are found in the later stages now described. They acquire stronger staining powers as the sphere stage is approached. Continued July 21—The duration of the stage in which the pro- toplasm remains in the condition of closely aggregated spheres, and which I call stage iii, varies from two to eight hours. The aver- age duration in a number of cases is about four hours. The most marked change which can be seen in the living condition during this period is in the disposition of the brown granules in the spheres. At first the center of the spheres is clear, the granules lying at their periphery, while in the later part of the stage the granules occupy the sphere leaving only a clear layer at the periphery. After stage iii the development may pursue one of two courses: I. In by far the greater number of cases that I have watched the spheres lose their sharply defined outline and gradually fuse with one another into one or a few lumps.” Sometimes long pseudopodia are thrown out during the process of fusion but this does not always occur. The lumps so found generally divide, forming smaller lumps of varying size which move apart by means of pseudopodia, and also exhibit amoeboid changes of form. It frequently occurs that one of these lumps attaches itself to the empty shell, spreading over part of the exterior and interior.’ The protoplasm remains in this condition for weeks. The smaller lumps appear gradually to break up into granules, losing their definite outline and apparently dying. The large lumps may retain their sharply defined outline for weeks, the movement of the protoplasm becoming gradually more sluggish, and the volume of the mass apparently de- creasing. What their ultimate fate may be I have not seen—but it appears probable that it is the same as that of the smaller divisions (lumps) into which the protoplasm divided—gradually disintegrating.” *7: 30-9: 30 p.m. 211-330 p. mi. * These conditions lasted until July 1, many other specimens being kept under observation. On this date Lister tabulates the stages of the process as follows: Stage 1. Premonitory halo formed but protoplasm still in shell. Stage 2. Proto- plasm emerged from shell but still in one mass. Stage 3. Protoplasm divided up into isolated spheres. Stage 4. Spheres fused to form a common mass sending out pseudopodia. Stage 5. The mass divided up into amoeboid lumps with pseudopodia. Lister’s preparations of shells in all of these stages are in our collection at South Kensington. i NO. 9 RESEARCHES OF JOSEPH JACKSON LISTER—-HERON-ALLEN 9 2. In some ten cases (out of say 150 which I have now seen) the spheres have separated after some hours, sending out long and abun- dant pseudopodia, and moving rapidly away from one another. Within 24 hours a second chamber is added to the sphere,’ and a calcareous shell is developed.’ In this condition they are readily recog- nized as young megalospheric individuals. July 22.—After writing the above yesterday it occurred to me that the first of the two processes described above was an abnormal one— the result of the impurity of the water. I therefore changed the water 1 This was first observed at 7:10 p. m. on July 2. Lister’s note (note-book, vol. ii, p. 91) reads “ The empty shell is now surrounded by a host of small bodies. These all possess a globular mass containing yellow protoplasm. In many cases a second mass shaped like the second chamber of a megalospheric form, and more transparent than the globular mass is present. In other cases two transparent 4-oval masses are present. Some of them have extended pseudopodia.” On July 3, at 9 a. m. these second chambers had highly accentuated themselves. (See draw- ing note-book iii, p. 27.) All the stages were observed on this day in another specimen between 9 a. m. and 9: 40 p. m. (drawing in note-book, vol. ii, p. 92). This had acquired its second chamber at 8: 30 a. m. on July 4. * This was first observed at 12:20 a. m. on July 5. At 9:10 a. m. the former specimen had its young “with a rough shell-hyaline material outside this.” (Note-book, vol. 11, p. 90.) *On July 7 (the day Lister began the account we are studying) at 10:15 a.m. he writes (note-book, vol. ii, p. 101) ‘‘ The specimen which yesterday morning at 10:30 a. m. was in stage 3, and whose spheres then separated, I have now transferred to picric with several of the spheres attached. They are ‘young megalospheric forms with a second chamber formed.” These observations were continued and repeated day after day with the same patient observations and accurate records. On July 11 Lister was able to construct a table, founded upon 23 specimens which had been observed, at the times passed in the stages, the average being: Stage I, 3 hours. Stage 2, 2 hours. Stage 3, 7 hours. (On the 12th he observed the same phenomena in Rotalia beccarii (Linn.) of which he made a beautiful drawing (note-book, vol. ii, p. 106).) The average for 12 specimens watched on July 13 was: Stage I, 4 hours. Stage 2, 2 hours. Stage 3, 8 hours. (The young Rotalia (66 specimens) gave an average of stage 1, 3 hours, 20 minutes. Stage 2, 1 hour, 30 minutes. Stage 3, 4 hours, 20 minutes. The observations went on as before, thereby confirming the accuracy of his previous records up to the 21st; on the 22nd he made the discovery as to the water which has been recorded in his own words, which now follow. When making dredgings at Plymouth, while this paper was awaiting publication (in April, 1929), we had the good fortune to find, in a dredging from inside Drake Island (the locality from which Lister obtained his material) a very large number of young Polystomellae, in exactly the condition here discribed—i. ¢., a megalospheric chamber, followed by one or two succeeding chambers. See our paper, “ The Foraminifera of the Plymouth District,” E. Heron-Allen and A. Earland, Journ. Roy. Micro. Soc., 1930, vol. 50, p. 194. se) SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 in two of the jars, putting instead of the aquarium water, water from beyond the Breakwater which I had in a bottle. Today six individuals have passed through the reproductive phase and all have pursued the second course—giving rise to young megalo- spheric individuals. Those (4) in which the protoplasm separated in the afternoon have already (9:35 p.m.) added a second chamber to the megalosphere, while those which have separated since 7 o'clock consist only of a spherical body, with abundant ray-like pseudopodia. These six individuals pursued the course described above up to the end of stage iii—the most noticeable feature about them being the large area covered by the protoplasm in the second and third stages— filling the area of the halo. This clears up the process in a most satisfactory manner.” To the abstract of the above given in his later works he merely adds: ‘The whole of the protoplasm of the parent is used up in the formation of the brood of young, the shell being left empty. The process from the first appearance of the halo to the dispersal of the young is complete in about 12 hours. ... . Each of the spheres was, in fact, a megalosphere. The microspheric parent has given rise to, indeed it has become, a brood of megalospheric young.” Lister was an expert micro-photographer, and in April, 1895, he obtained fresh material from Plymouth, and repeated his obser- vations in his own laboratory, at Cambridge. He heads his notes: “ Polystomella material started in dishes, April 30. Several micro- spheric individuals have reproduced in the manner seen at Plymouth last summer. In a few cases the fusion has occurred, but many have formed normal young.” His observations, like those of 1894, were made by the “hanging drop” method in the use of which he was an expert. His notes at this time relate to the flagellispore method of reproduction by the megalospheric specimens, but from May 22 to 24 he made a wonderful series of micro-photographs, 24 in number from a single microspheric individual of which 15 were made into lantern slides, which slides Mrs. Lister has presented to our collection. A selection of these together with certain of the photographs (which are now being published for the first time) are now available, for all time, for the use of students of Protozoology. In all, 20 photographs are here reproduced. They may be tabulated as follows: *On July 25 he writes ‘ There is reason to believe that the aquarium water is affected by the asphalt lining of the tanks.” He tested this with further Polystomellae on the 26th in “outside water” between 8:30 a. m. and 7 p. m. with brilliantly successful results. His notes on Polystomella cease, for this time, here. NO. 9 RESEARCHES OF JOSEPH JACKSON LISTER—-HERON-ALLEN neat Lantern slide, Heron-Allen and Earland Figure Series May 22, 1895 Collection I aL 1:00 p.m 12/32 | The “ premoni- 2 Bee Brea, Ue © Tae Aimy poets te tory halo.” 3 1B 3) Amos a? 12/33 Stage ii. 4 E. 4 AvAQma. 12/34 ey 5 E.5 Gz 12/35 a 6 E.6 O700l 12/36 # 7 B.7 G2 sau. 12/37 i 8 E. 8 TAOS ee MURA iy a mere ence Stage iii. 9 E.9 SATS ee a) VP Nahar seers - 10 E. 10 8:55 7 12/38 ” EE Bont On60--%* 12/39 uy 12 E. 12 Ors O mee 12/40 e Tes ets MOR 12/41 2 14 E. 14 DES) oe 12/42 Final stage. 15 E.15 nits Age 12/43 ag 16 E. 16 EY SO 12/44 a U7, a7, Tha55. 4 12/45 -s May 23, 1895 18 E. 19 OAL ay | ours e y May 24, 1895°¢ 19 E. 19 iS oy 12/49 a 20 F.r&2 " Deep view. » Nearer view. © There is something wrong here. J. J. L. dated this slide May 23, 1895, II: 50 a. m. but it obviously belongs here as a second chamber is in process of formation. I think it should have been dated May 24. After E. 18 (which is not reproduced) the slides are not numbered, but his register of photographs gives the numbers 109 et seq. The last of these, figure 20, is one of the two slides in the collection, showing different magnifications of the same object, which are regis- tered as Ser. F. 1 & 2 but no dates or times are given. They are from another specimen and represent the post-final stage (probably 25-26 May) when a second chamber has been added. They are registered in the Heron-Allen and Earland Lantern-slide Collection as 12/46-47. In conclusion I may be allowed to pay a tribute of warm gratitude to Mrs. Lister, whose early death occurred shortly afterwards, for the public spirit which led her to present the Lister Collections in general, and these priceless note-books, preparations (there are nearly 450 of P. crispa alone in our collection at South Kensington), and lantern slides, to the nation for the use of future generations of students. I desire, also, to express my gratitude to Dr. J. A. Cushman for correcting the proofs of this paper. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82, NO. 9. PL. 1 For explanation, see page IT. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82, NO For explanation, see page II. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLE S25 NO oy rie. For explanation, see page IT. ‘11 ased 995 ‘uoleuR[dxe 104 b “Id ‘6 “ON ‘28 “10A SNOILO3A1100 SNOANVITISOSIW NVINOSHLINS ‘Tr osed as ‘uoneurldxs 104 G “1d '6 “ON ‘28 “10A SNOILO3S11090 SNOANVIISZOSIN NVINOSHLINS ‘It aed 99s ‘uoeuRrldxea 104 9 “1d “6 “ON ‘28 “10A SNOILO3A1100 SNOANVITISOSIN NVINOSHLINS ‘Ir ased dos ‘uoleurldxo 104 LZ “1d ‘6 “ON ‘28 “10A SNOILO31100 SNOANVITISOSIN NVINOSHLINS SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 82, NUMBER 10 MORPHOLOGY OF THE BARK-BEETLES OF THE GENUS GNATHOTRICHUS EICHH. BY KARL E. SCHEDL (PUBLICATION 3068) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION JANUARY 24, 1931 The Lord Baltimore Press BALTIMORE, MD., U. S. A. MORPHOLOGY OF THE BARK-BEETLES OF THE GENUS GNATHOTRICHUS EICHH. By KARL E., SCHEDL CONTENTS ‘Liciynaahvie itor ead c Geen Ganictnc 8 Gisie ote re a Ce BOR eS oie eirs SO nes numa eee EMstractsvoithe literature tp) tondates as sacs nese ies nee. ok Numer Ie seCIItl Senate core eucyescterswstevel vias tae yamsatnithe Ceara a ae aseiatnn wsla ores B: Gnathotrichus matertarius Fitch............0.+.2..+-+eceeess> PVE COLE VATI CUE apet a cpeter ie eke icy ete il « ase icvokean te onsitucnete hens lst Netane ie snc reree @RGS SoS Debrstantaa (OTe TIDINGS imetete rare saver al cay stave eis serern ereial onset eevee Rhee Rae Gites General appearance, vestiture, color and size..................... “TTESUNEETA SS 5s eee SEROMA CCR A Oi cic: teas De Oa SORES ets sihnesapperidaresuor the headiss svar ceeraiecie st ates Seine eesti waver MIB eeaATItEN TAGs fecere\s, 5 Sccie ciseno ey ORES RIO ee eS rae al sd ee telist ie ohs BINTE STOUT PALES 1; tera ected sreyey otabeeear ares euros Son eats oy arcane aires ons “OLAV ARG) eb Sieben oP RiP MC RRR SIO RN i tics ecat ye Aum ia I PRhetprothorax wane aie errr t ee AC re ak nan eee silseemesothoraxps Hopkins; Aw Di(a4): The author examined one specimen from Chaleo and another from Michocan, Mexico, and suggested that Blandford’s Gnathotrichus consentaneus is identical with sulcatus Lec. 1905... CURRIE, Jka Po (32) Copy of Hopkins, A. D. Fir is replaced by lowland fir. LO07. FALL, EC. and Cockerrrn, DAG G@s6)r Gnathotrichus sulcatus (Hopkins MS.). —— Beulah (Skinner). 1909. SwaIne, T. M.(40). References to literature only. 1910. Haceporn, M.(42). References only. 1914. SWAINE, J. M.(47). See retusus Lec. 1918. SwaIne, J. M.(49). No new data concerning the description and the biology. Host trees: Grand fir, western hemlock, Douglas fir, western white pine. Distribution: Generally distributed throughout southern British Columbia, extending southwards. In sap-wood and heart- wood of dying and recently killed trees, and more rarely in those apparently sound. 1922. Hoppine, R.(5r). According to the author Gn. sulcatus breeds in the following host trees: Pinus monticola Dougl., Abies concolor Parry, Abies mag- nifica Murr., Abies grandis Lindl., Pseudotsuga taxifolia Britt., and Tsuga heterophylla Raf. SYNONYMA A. Gunathotrichus materiarius Fitch Tomicus materiarius Fitch (Fitch, Schwartz, 1890, Packard, 1890). Crypturgus materiarius Fitch (Zimmerman, Packard, 1869). Gnathotrichus corthyloides Eichh. Pityophthorus materiarius Fitch (Leconte, Packard, 1881). Cryphalus materiarius Fitch (Provancher). B. Gnathotrichus retusus Lec. Cryphalus retusus Leconte, 1868. Pityophthorus retusus Lec. (Leconte, 1876). NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 15 C. Gnathotrichus sulcatus Lec. Cryphalus sulcatus Leconte, 1868. Pityophthorus sulcatus Leconte, 1876. Common NAMES A. Gn. materiarius Fitch. Pine timber-beetle (Fitch). Timber-beetle (Hopkins, 1893). Eastern pine wood stainer (Hopkins, 1904, Felt, 1906). B. Gn. retusus Lec. Timber-beetle (Hopkins, 1893, Swaine, 1914). Pine hole borer (Swaine, 1914). C. Gn. sulcatus Lec. Western hemlock wood stainer (Hopkins, 1904). Tue CHITINOUS SKELETON OF THE ADULT GENERAL APPEARANCE, VESTITURE, COLOR, AND SIZE The general form of all three species is slender in both sexes, cylindrical, with the head concealed from above by the pronotum. The pronotum is longer than wide with the sides parallel on more than the caudal half and broadly rounded in front. The elytra are slightly narrower or as wide as the pronotum, subparallel as far as the origin of the declivity, sometimes slightly tapering posteriorly ; moderately broadly rounded behind. Length and relative proportions. (Dorsal aspect) .— Gnathotrichus materiarius Fitch. Length of the body (elytra and pronotum; head concealed from above), 3.06 mm. The body is 3.11 times as long as the width of the pronotum. Width of pronotum, 0.98 mm. The elytra are 1.46 times as long as the pronotum. Examined specimens, 12. Gnathotrichus retusus Lec. Length, 3.72 mm. The body is 3.23 times as long as the width of the pronotum. Width of the pronotum, I.15 mm. The elytra are 1.54 times as long as the pronotum. Examined specimens, 10. VOL. 82 MISCELLANEOUS COLLECTIONS SMITHSONIAN 16 ‘uinjouoid jo uoIssaidut ssiaAsuety “6 fyOOT Burm [esoze] ‘f ‘snsie} ‘a feiqyy ‘p {anuiay ‘9 {exoo ‘q tssao0id 9]OrAe]o pue prloore10s “p !xojtaA ‘ay 941819} “7 Sywuins ‘wg ‘ajoeiids ‘dg ‘umyjaynos “95 *TaT3NOS ‘I$ ‘!wnynoseid Bd ‘xe10yjoid “‘Yqjiq :wnuse3soid 4s4q ‘unjouoid “usg ‘epndeid “gq ‘eijrxeur ‘xpy !xes0yyejou Yu - WNU19}SE}9UT SIN :XB1OYJOSOU “YISPY SUINUISJsSOSaUI ‘ysspy ‘Sssea_ B[ppllu “Ty ‘a[qipueu ‘pyy fyu01y ‘47 3 883[9103 TA ‘dytIne[dodéy 148 :ssaq pury “7H :ek9 punoduios ‘ty tumusajsidea “4sdy suosouida “dy feyanejdide “dq ‘euioys da ‘dy ‘euuojue “Up ‘podse [esoze] ‘QpeUl ype ‘YY SsuiapiaajoU SNYyIAJOYJWUN—'T “OI uswopaqy —UWW— U1 SW-Ul d-——————__D B 83 H—_—__ | “OPUS 3]S - H I if ' 1 i co pee ---Gi-~-- (ooo ee Seo NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL V7, Gnathotrichus sulcatus Lec. Length, 3.59 mm. The body is 3.38 times as long as the width of the pronotum. Width of the pronotum, 1.07 mm. The elytra are 1.60 times as long as the pronotum. Examined specimens, 10. _—— UNW—ulsw——yWd Fic. 2—Gnathotrichus materiarius Fitch, adult male, ventral aspect. An, antenna; Cc, coxal cavity; Co, coxa; Ep, epistoma; Epm, epimeron; Epst, episternum; Ey, compound eye; Gu, gular area; Hst, hypostoma; La, labium; Msst, mesosternum; Msth, mesothorax; Md, mandible; Mtst, metasternum; Mtth, metathorax; Mz, maxilla; Pr, pregula; Prst, prosternum; Prth, prothorax; st, sternite; St/, sternellar area; a, median line. Color —The color ranges from a reddish-brown to nearly black in mature specimens; it is of no importance in this genus. V estiture —In general it can be said that all three species are with- out extraordinary hair characters; few large bristles occur on the declivity. However, by careful examination under the microscope it was found that all external parts are more or less covered with fine hairs. VOL. 82 SMITHSONIAN MISCELLANEOUS COLLECTIONS 18 “SolIe][IxXe Ino} oy} “PY ‘E ‘ce ‘I SSUIM JO 38UIY SUIP[O} ULIpaut ‘6 ‘snsie} ‘a feiqi “p fanulay “2 feqoy Sum “7A ‘BuIM dovIOYyeJoUI ‘yy $9}Id19} “7 sapoeiids ‘dg> ‘ulaa [eysooqns ‘o2¢ :xe10y4}e}OW Jo Wnznos ‘9G {sniper ‘y ‘unyje3ynos}sod 10 winjoujsod “asq ‘S33 a[ppim ‘7p ‘sulsa ueripeu ‘py ‘foyanatdodAy “dy ‘s3o{ pury “7H ‘ssa 910} “Ty ‘Sayanajdida dq fe1zAja “7q PAATOOp e4AZATO ‘GQ ‘snziqno ‘nD fexoo ‘oy feuuajue “up ‘ypodse jesiop ‘ajew ynpe “Yo smispidazou snyri4joyyoUyH—E “OTT b 19-7 ——-00- LE 7st BL, z NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 19 Sculpture —The front and the elytral declivity are the only bearers of specific modifications. The sculpture of the pronotum and _ the elytra, which is very useful in distinguishing the species in many other genera of the Scolytidae, does not vary to any extent in this genus. Secondary sexual characters—-Secondary sexual characters were found in the development of the hairs on the antennae, the number of fully developed tergites and in the number of spiracles mainly. THE HEAD The head capsula or cranium (figs. 4-7) is dorsally divided by the epicranial suture. The sutura fronto verticale Berlese or coronal su- ture (figs. 5, 6, Cos) is distinct in all three species examined. In Gnathotrichus retusus Lec., and less pronounced in Gn. materiarius Fitch, this suture and a short piece of the sutura metopica da Miall and Denny or frontal suture become elevated near the junction, form- ing a Y-like ridge. The slightly raised line (figs. 4, 5, a) which origi- nates at the upper margin of the antennal groove (figs. 4, 6, b, 7, c) and which is directed toward this junction may be considered a rem- nant of the frontal suture. These anterior remnants of the frontal suture are never connected with the posterior portion. Front.—The area between the frontal sutures is largely occupied by the frons (figs. 4, 5, 7, Fr). The shape of the front is plano- convex ; the median line is slightly raised, and there is a shallow de- pression on each side of the latter. The front is sculptured by scratches which radiate from the center of the anterior margin, and which ex- tend over the entire sclerite, becoming less distinct and less dense towards the outer margin. These scratches look as though they had been made with a needle point, and therefore have been called accicu- lation by several authors. Scattered over the acciculate area are small but deep, sparse punctures. Bristles varying from short to moderately long occur over the entire front; most of these originate in punctures. They are more numerous in the antero-lateral corners. Specific modifications :— A—Acciculation strongly developed, close; front with punctures near the outer margin and antero-lateral region only, with bristles very sparse in the acciculate, area (fig. 5, Ac). Gn. sulcatus Lec. AA—Acciculation weakly developed or obsolescent, more or less re- stricted to the median anterior area; front elsewhere punctu- late, bristles more numerous. Gn, retusus Lec. and materiarius Fitch. 20 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 Labrum, clypeus and epistoma—The labrum and clypeus are not evident as separate sclerites. The epistoma (figs. 4, 5, 7, ep), probably also containing elements of the labrum and clypeus, is not separated from the front by a distinct suture or line. It is present as a ridge and forms the anterior margin of the front. This region is widened later- ally, and is connected with an elevation which surrounds the antennal Fic. 4.—Gnathotrichus sulcatus Lec.: Head, lateral aspect. An, antenna; Ep, epistoma; Ey, compound eye; Fr, frons; Ge, gena; La, labium; Md, mandible; Mz, maxilla: Oc, occipital area; Ve, vertex; a, frontal suture; b, antennal groove. Fic. 5.—Gnathotrichus sulcatus Lec.: Head, dorsal aspect. Ac, acciculation; An, antenna; Ep, epistoma; Ey, compound eye; Fr, frons; Md, mandible; Mx, maxilla; Cos, coronal suture; Ve, vertex; a, frontal suture. scrobe. In the middle of the anterior margin, an evenly rounded emargination is visible which may be called serratus epistomalus (fig. 7, SE) and which corresponds to Hopkin’s median impression. From the serratus epistomalus the acciculation of the front radiates. The epistoma is without sculpture and bears a row of bristles on its posterior margin. The mandibles articulate with the underside of the epistoma. iN(GE 106} MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 21 Gula.—The gula is bounded by the two very closely placed gular- sutures (figs. 6, 7, Gus) and widens anteriorly to form the pregula. Fic. 6.—Gnathotrichus sulcatus Lec.: Head, ventral aspect. An, antenna; Cos, coronal suture; Ey, compound eye; Ge, gena; Gus, gular sutures; Hy, hypostoma; La, labium; Md, mandible; Mx, maxilla; Oc, occipital area; i bi ( i ca, occipital apodeme; Oct, occipital foramen; Pr, pregula; a, dorsal articulation of the mandible; }, ventral articulation of the mandible; c, antennal groove. R Fic. 7.—A, Gnathotrichus sulcatus Lec.: Head, oral aspect. B, Gnathotrichus retusus Lec.: Pregula. An, antenna; Ep, epistoma; Ge, gena; Gus, gular sutures; Fr, frons; Hy, hypostoma; La, labium; Mx, maxilla; Pr, pregula; SE, serratus epistomalus; a, dorsal articulation of mandibles; b, ventral articulation of mandibles; c, antennal groove. These two distinct sutures appear to be exceptional in this family. Hopkins apparently did not find any double sutures in his investi- gations. 22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 In Gnathotrichus, the pregula (figs. 6, 7, Pr) is always without sculpture or hairs. The very distinct specific modifications are de- scribed in the following key: A—Pregula flat, triangular, not produced anteriorly, its anterior mar- gin continuous with those of the géna. Gn. sulcatus Lec. AA—Pregula convex, produced anteriorly, its anterior not continuous with those of the gena. B—Pregula very convex, extending far beyond the genal margin. Gn. retusus Lec. BB—Pregula feebly convex, extending slightly beyond the genal margin. Gn. materiarius Fitch. E picranium.—The remaining lobes of the cranium situated between the epicranial suture, the gula, and the foramen bear the compound eyes (figs. 4-6, Ey), the antennae and the articulations of the mouth- parts. For merely descriptive purposes these lateral areas of the cranium have been divided into several regions. The occipital area (figs. 4, 6, Oc) surrounding the occipital foramen is not limited an- teriorly in Gnathotrichus. However, there occur obscure lines which may be regarded as homologous with the occipital suture. The epi- cranium or parietals (Crampton), the gena, and the vertex do not show any sculpture which exhibits specific differences. The hypo- stoma (Hopkins) (figs. 6, 7, Hy), an area corresponding to the epi- stoma, which like the former belongs morphologically to the epicra- nium, is well developed. It is in the form of a semicircular band and bears at its extremities the ventral articulations (figs. 6, 7 b) of the mandibles. From the oral aspect it is visible; from the ventral, it is hidden by the pregula and the gena. Other regions, such as the pregena (Hopkins), etc., are not at all distinct or limited and are therefore of no interest in this discussion. THE APPENDAGES OF THE HEAD THE ANTENNAE The antennae present good generic characters ; the species modifica- tions are less important. The sexual differences are distinct also. All the longer setae of the antennae are feathered. 1 The hypostoma, as the term is used here, or the ventral angles of the postgena, is the bearer of the maxillare and not the labium. A submentum, as this term was used by Hopkins in Dendroctonus, is not defined by sutures. NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCH EDL 23 The scape (fig. 8, A, S) is slender and clavate toward the apex. Hairs and punctures are rather sparse. The scape is about as long as the funicle and the club together. The funicle (fig. 8, A, F) is Fic. 8, A.—Gnathotrichus retusus Lec., adult female: Antenna, interno- lateral aspect. C, antennal club; F, funicle; S, scape; p, pedicle; 2, 3, 4, 5, joint of the funicle; 1’, 2’, 3’, joints of the club. Fic. 8, C—Gnathotrichus sulcatus Lec., adult male: Antenna, externo- lateral aspect. pill =e vy h fi Fic. 8, B—Gnathotrichus retusus Lec., adult female: Antenna, externo- lateral aspect. Fic. 8, D.—Gnathotrichus sulcatus Lec., adult male: Antenna, interno- lateral aspect. five-jointed and distinctly shorter than the club. The pedicle (fig. 8, A. p) the first and longest of all joints, is as long as joint two and three together. The setae and punctures are more concentrated on the apical half of the pedicle, only two small bristles occurring near the basal articulation (fig. 8, B). The other joints decrease in 24 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 length but increase in width towards the club. All the joints bear numerous punctures and hairs except the second which has neither. The club (fig. 8, A, C) is from 1.21 to 1.35 times as long as wide, egg-shaped in outline, widest near the apex and strongly compressed. Two nearly continuous septate sutures divide the club into three joints. The first and third joints are nearly equal in length; the second is distinctly shorter. The septae are arcuate and distinctly visible from the externo-lateral aspect (fig. 8, B, C). On the interno- lateral side (fig. 8, A, D) they are indicated by single sutures. Each of the joints is covered by numerous hairs and punctures. Externo- laterally these are closely placed and arranged in arcuate rows ; interno- laterally, they are sparse, and the punctures are more numerous. The females (fig. 8, A) bear, moreover, on the interno-anterior margin of the club a few very long hairs. The anterior setae of the third, fourth, and fifth joints of the funicle are longer in this sex. These are the only external characters by which the sexes may be distinguished when the elytra are kept in the closed position. Specific modifications :— A—Septae in the form of continuous bands of equal width through- out, slightly less pronounced medially; externo-lateral side of the club with minute, transverse wrinkles and small punctures producing a slightly roughened surface (fig. 8, ENG IE Ne Gn. retusus Lec. AA—Septae wider laterally, indistinct and narrow medially ; externo- lateral side of the club smooth or with very minute, sparse wrinkles; club stouter. B—Externo-lateral side of the club smooth, interno-lateral side with numerous hairs and punctures (fig. 8, C). Gn. sulcatus Lec. BB—Externo-lateral side of the club with minute wrinkles, interno-lateral side with very few hairs and few punctures ; club very stout. Gn. materiarius Fitch. THE MOUTHPARTS ' The mouthparts present generic as well as specific characters. They include the mandibles, the first maxilla and the second maxillae or labium. NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 25 Mandibles—The mandibles (fig. 9) are very much alike in all three species, so much so that it is not possible to distinguish them by mandibular characters. The shape is stout and triangular as in most Scolytidae. The apical tooth (fig. 9, a) and the subapical tooth (fig. 9, b) are well developed and separated by a deep emargination. In contrast to other genera, two median teeth (fig. 9, c) occur. The latter are rather feebly developed and the separating emargination is shallow. The molar tooth (fig. 9, d) is evenly rounded. There are one lateral and two dorsal setae (fig. 9, f, g). Other details are illustrated in figure 9. No specific differences have been found in these. Fic. 9.—Gnathotrichus materiarius Fitch: Mandible, dorsal aspect. a, apical tooth; b, subapical tooth; c, median teeth; d, molar tooth; e, dorsal area; f, lateral bristle; g, dorsal bristles; h, transverse ridge; i, anterior fossa; k, condyle; /, posterior fossa; m, posterior impression; n, condyle of ventral articulation; 0, extensor tendon; », retractor tendon; q, extensor disk; r, retractor disk. The Maxilla—The maxillae (figs. 2, 6) are exposed on each side of the labium. Each is held in such a way that the cardo is parallel with the long axis of the head; the stipes, lacinia, and galea are at right angles to the cardo; the second and third palpial joints are slightly curved outwards. The galea and lacinia are represented by two lobes which are fused except at the apex where they are sepa- rated by a moderately deep notch. The stipes is separated from these fused lobes by a very fine, feeble suture on the outer side; on the inner side, no suture is evident. Another paper will deal with the generic differences in the maxilla of Guathotrichus Eichh. and re- lated genera. Nevertheless, it should be noted that, as far as known at present, the labium and the maxillae in the genus Pityophtorus Eichh. always bear at least a few feathered bristles ; in Gnathotrichus 26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Eichh. these bristles are simple. This is important, as it has been seen that the character “ maxilla spinose ” in Pityophthorus Eichh. and “ maxilla pilose”? in Gnathotrichus Eichh., as used by several Fic. 10.—Gnathotrichus sulcatus Lec.: Maxilla, outer aspect. C, cardo; G, galea; P, palpus; 1, 2, 3. first, second and third joint of the palpus; a, articulation of the maxilla; b, stipes; c, palpi re area; 1, anterior emargination separating galea and lacinia; k, dorsal setae of the galea; /, median setae of the galea; m, cardol setae. } | - \ (—— NaN st 4 l) raz sey a nie y} / a SS ee ee b = jj My Ee SiG me Ni Fic. 11.—Gnathotrichus sulcatus Lec.: Maxilla, inner aspect. C, cardo; L, lacinia; P, palpus; 1, 2, 3, first, second and third joint of the palpus; a, articulation of the maxilla; b, stipes; c, palpiferal area; d, subgaleal area; e, posterior setae of the lacinia; f, dorsal setae of the lacinia; g, median ‘setae of the lacinia; h, papilla. authors to separate Gnathotrichus Eichh. from the rest of the Pityoph- thorinae does not hold, as will be shown in the discussion of the lacinia and galea. The maxillae exhibit no specific differences of importance in Gnathotrichus. The maxillae are illustrated in figures 1OanGd iL. NO: LO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 27 Cardo.—The cardo (C) is similar in shape in all three species and is articulated with the ventral angles of the postgena in such a way that the maxilla can be moved laterally as well as in a dorsal-ventral plane. The longitudinal axis of the cardo and that of the stipes (b) enclose an angle of about ninety degrees or even a little less. The articulation of the stipes and the cardo is similar to that of other genera of the family. There is also an articulation between the sub- galea and the cardo. In figure 12, which illustrates this fact, the cardo and the rest of the maxilla are stretched to show the connection. The inner side of the cardo is smooth; the outer side shows from five to seven hairs which may be called the cardol setae (m). Stipes.—On the outer side the stipes is defined as an elongate, sub- parallel sclerite; on the inner side it is fused with the lacinia. The Fic. 12—Gnathotrichus materiarius Fitch.: Maxilla, stretched, the subgalea showing. setae are not very numerous, about six to eight being present. These are more concentrated anteriorly near the base and near the apex. The latter, situated on the apical area of the stipes, may correspond to the palpiferal setae of some authors. The palpifer (c) being a topo- graphical area of the stipes only, is not limited by lines or sutures. Lacinia and galea.—The lobus internus or the lacinia and the lobus externus or the galea are largely fused to form a single large lobe. Apically they are distinctly separated by a moderately deep emargina- tion (i) or notch. The inner free lobe is distinctly larger than the outer one. Posteriorly they are fused. It will need much further investigation to decide the exact areas of these two lobes. In the meantime it is proposed to call the inner lobe and the inner surface of the combined lobes the lacinia and the outer free lobe and the outer surface of the fused part the galea. 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The lacinia bears on the anterior portion of the free dorsal margin short, stout, blunt setae (f) which are slightly incurved at their tips. Fic. 13, A.—Gnathotrichus retusus Lec.: Labium, ventral aspect. L, ligula; M, mentum; Pp, palpifer; a, base of ligula; b, neck of mentum; c, ventral setae of the palpifer; d, anterior part of ligula; e, first joint of palpus; f, second joint of palpus; g, third joint of palpus. Fic. 13, B.—Gnathotrichus retusus Lec.: Labium, dorsal aspect. P, palpus; L, ligula; a, articulation of the labium; b, base of ligula; c, dorso-lateral setae of the palpifer; d, dorso-anterior setae of the ligula; e, f, g, first, second, and third joint of the palpus. Fic. 13, C—Gnathotrichus sulcatus Lec.: Labium, ventral aspect. Fic. 13, D.—Gnathotrichus sulcatus Lec.: Labium, dorsal aspect. These setae gradually become longer, more slender, and pointed pos- teriorly (e). Near the subgaleal area (fig. 11, d) they are about three times as long as on the dorsal margin. Besides these setae on the outer NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 29 margin of the lacinia numerous bristles (g) are scattered over the entire lobe ; the surface is slightly reticulate. Basally, the united lacinia and galea end in a lobe, the subgaleal area (d), which is distinctly defined on the inner side by an impressed line. The galea bears a short row of slender setae (k) on its free dorsal margin; the surface is armed with rather sparse, long hairs (e). Adopting the terms of other authors, it may be said the lacinia is pilose on its dorsal margin and spinose on its posterior and that the galea is spinose. Palpi—tThe palpi (P) are three-jointed. The first joint is the longest, the second and the third are subequal in length. Anteriorly joints one and two bear setae, joint three punctures only. There occur slight differences in the size and the shape of the joints in the species, but they are not distinct enough to be of importance. Labium—tThe labium (fig. 13), consisting of the mentum, the ligula, and the palpi mainly, presents the most important generic and specific characters of the mouthparts. The shape of the mentum (fig. 13, M) is similar in all three species. It is flask shaped, the palpifera always being wider than the neck (fig. 13, b) and the base of the mentum and the latter always nar- rower than the ligula (fig. 13, L). The basal portion of the mentum is feebly widened in Gn. retusus Lec. (fig. 13, A) and strongly widened in Gn. materiarius and sulcatus (fig. 13, C). In Gn. sulcatus and materiarius, the mentum and the ligula are separated by deep sutures throughout, even at the extreme base of the ligula; in retusus they are similarly distinct except at the extreme base before which they com- pletely disappear. The sculpture of the mentum on the ventral side (fig. 13, C), except for a few distinct punctures, is smooth in Gn. sulca- tus. Gn. materiarius is very similar but it shows slight evidences of transverse wrinkles also. In Gn. retusus the punctures are obsolete ; the wrinkles are strongly developed and become on the neck of the mentum and the basal half of the palpifer more or less toothlike (fig. 13, A). All the setae are simple bristles (c), and there are eight to ten of these bristles on each half of the ventro-lateral side of the apical third of the palpifer. In Gn. retusus and materiarius there are ten of these bristles ; in sulcatus eight is the usual number. Ligula—lIn this genus, the ligula (L) is much larger and more prominent than is usual; it is wider than the mentum in its basal half and is distinctly limited by sutures at the extreme base of the labium except in retusus. The ligula (fig. 13, L) extends in all three species a little farther anteriorly than the first joint of the palpus. Its 30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 » shape is elongate ; it is subparallel with two more or less distinct con- tractions when viewed from the dorsal aspect. The basal portion is semicircular in cross-section, while the anterior, unfused part is strongly compressed. In Gn. retusus Lec., the ligula is more parallel and the contractions less distinct than in the other species. The anterior margin is very feebly, shallowly emarginate or evenly rounded ; however, this does not seem to be constant in individuals of the same species. On the ventral aspect, there is on each side near the anterior margin a row of setae (d). No specific differences have been found either in the shape or in the number of these setae which vary in number from three to seven in each row. The sculpture of the ligula on the ventral aspect in all three species is very much alike, being nearly smooth or feebly transversely wrinkled. Dorsally Gn. retusus shows similar transverse, toothlike wrinkles on the mentum; the basal portion only is smooth. Gn. materiarius and sulcatus have the corresponding area smooth with slight indications of transverse wrinkles on the sides. Palpi—trhe palpi are directed ventrad. Each is composed of three segments, decreasing in size toward the apex. Segments two and three bear dorsally a plush-like arrangement of hairs, while the first joint has a few scattered hairs only. Ventrally, the setae are more sparse and are intermixed with punctures on segments one and two; segment three has no setae but a few punctures. Summary of the specific characters :— A—Base of the mentum scarcely widened basally, fused with the ligula before the basal margin of the latter; mentum and ligula when seen from above with strongly developed, tooth- like, transverse wrinkles ; ligula subparallel. Gn. retusus Lec. AA—Base of the mentum distinctly widened basally, extending to the basal margin of the labium; mentum and ligula when seen from below smooth or with slight indications of trans- verse wrinkles ; contractions of the ligula well developed. B—Ventral side of the mentum smooth, with few punctures. Gn. sulcatus Lec. BB—Ventral side of the mentum with transverse wrinkles. Gn. materiarius Fitch. THE THORAX The three segments of the thorax, pro-, meso-, and metathorax _ (figs. I, 2 and 3) are clearly defined in this genus as is usual in this family. Each of these segments has as a basis three primitive ele- NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 31 ments, the dorsal plate, or tergum, the ventral plate, or sternum, and the lateral area, or pleuron. The thoracic segments and their elements vary considerably in shape and size. The protergum, or pronotum, is nearly twice as long as the tergum of the metathorax. The mesoter- gum, still shorter than the latter, is represented by a short triangular area only. The prosternum is about half as long as the metasternum and about one-third the length of the pronotum, giving the pleural area of the prothorax the shape of a trapezium. The mesosternum is present as a plate nearly equal in size to the mesotergum; the meso- pleura are also developed in proportion, giving the mesothorax the shape of a short tube. The metathorax, more complicated in struc- ture, represents the segment in which all three primitive elements are well developed and defined. THE PROTHORAX In the prothorax the tergal, pleural and sternal areas (fig. 14) are fused, forming a continuous chitinous tube. However, corresponding elements to other thoracic segments are visible due to the different kinds of sculpture. Taxonomically the prothorax bears generic char- acters but none of specific importance. The two openings of the tube- like prothorax, the anterior and posterior foramina, are bordered by a fringe of closely placed hairs which arise from the inner margin. Pronotum.—The pronotum (figs. 1, 2, 3 and 14) is one solid plate by which the head is concealed. The dimensions are as follows: Gn. materiarius Fitch., length, 1.23 mm., width, 0.98 mm. Gn. retusus Lec., length, 1.44 mm., width, 1.15 mm. Gn. sulcatus Lec, length, 1.35 mm., width, 1.07 mm. The measurements are the average of 10 specimens from each species. Seen from above, the sides of the pronotum are subparallel on the posterior margin, while the anterior margin is broadly rounded. The anterior margin bears 10 to 16 low serrations which are only slightly longer toward the median line and sometimes fused at their base. On the anterior area, that is, the area in front of the summit which consists of a short slightly curved ridge and is placed a short distance before the middle of the pronotum, occur many comparatively small and low serrations arranged in concentric rows and decreasing in size towards the summit. Behind the summit the surface of the pronotum is covered with punctures. There are two kinds of punctures; the one comparatively coarse in contrast to the other but fine compared to those in other nearly related genera; the other, minute and only 3 . 32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 visible under higher magnification. The coarser punctures are sparse, deep and distinct, the minute ones closely placed giving this part of the pronotum a more opaque appearance. The posterior margin is slightly arcuate. Immediately anterior to the posterior margin there is an impressed line giving the intermediate space the appearance of a low ridge. This raised margin served as one of the main characters in placing this genus near Pityophthorus and allied genera. The pro- notum is covered with inconspicuous hairs which are longer and C Fic. 14.—Gnathotrichus sulcatus Lec.: Prothorax, ventral aspect. a, anterior foramen; b, posterior foramen; c, anterior margin of pronotum; d, posterior margin of pronotum; CC, coxal cavities; Epm, epimeral area; Eps, episternal area; ICP, intercoxal process; Peps, preepisternal area; Pst, poststernal area; St, sternal area; T, tergum or pronotum. coarser anteriorly. Posterior to the summit occurs a shallow trans- verse impression. The lateral limitations of the pronotum are not clearly defined but near the postero-lateral angle is a longitudinal ridge which may be considered as a remainder of the pleuro-notal suture. Pleural area.—The propleural area (fig. 14) is represented as one continuous plate in the shape of a trapezium of which the base is formed by the remainders of the pleuro-notal suture. Ventrally the pleural area is completely fused with the prosternum (St). Externally no sufficiently distinct lines are present to justify the distinction of subdivisional plates as episternum, epimeron, etc. Nevertheless there can be distinguished three parts of different structure which one may call the preepisternal (Peps), the episternal (Eps) and the epimeral NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 8) area (Epm). The preepisternal area is flattened, slightly depressed with a surface smooth except for a few minute wrinkles parallel to the longer axis. The episternal area is entirely covered by continua- tions of the serrations which occur on the anterior half of the pro- notum. A narrow strip along the posterior margin of the propleuron, quite distinctly limited to the surrounding plates by its transverse wrinkles, may be called the epimeral area. Fic. 15.—Gnathotrichus retusus Lec.: Prosternum and fore legs. C, coxa; F, femur; ICP, intercostal process; Pst, poststernal area; St, sternal area; Ta, tarsus; 7%, tibia. Sternal area.—The lateral ill-defined sternal area is largely occupied by the coxal cavities (CxC). The intercoxal process (ICP) be- longing to the intercoxal or sternellar plate is clearly defined and very short so that the coxae touch each other. The sternum proper and the presternal area are again not limited by sutures but by dif- ferences in sculpture. Prothorax.—The distinguishing characters of the prothorax are: I. The pronotum of Gn. materiarius Fitch is a little more slender than that of Gn. retusus Lec. and sulcatus Lec. 2. The punctures of the posterior half of the pronotum of Gn. retusus Lec. are somewhat coarser than in the case of the others. 34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 THE MESOTHORAX The mesothorax is the shortest of the three thoracic segments. The form is that of a ring with the anterior diameter smaller than the posterior one. The meso- and metathorax are very closely connected, giving the appearance of one single unit. Seen from above (dorsal) the scutellum only is visible, while in the lateral and ventral aspect the mesopleura and the mesosterna can be distinguished. The two Fic. 16.—Gnathotrichus retusus Lec.: Mesothorax, view from anterior foramen. The parts are disconnected by stretching under the coverglass. A, external aspect; B, internal aspect; Co, coxa; El, elytra; Ep, epimeron; Pr, preepi- sternum; Psc, prescutum; Eps, episternum; Pst, presternum; Pstr, poststernellum; Sct, scutellum; St, sternum; St/, sternellum; Stu, scutum; Tr, trochanter; a, articulation of elytra; b, clavicola; c, pleural hook of scutum; d, pleural clavicola. pairs of appendages are implanted between the pleura and tergum and the pleura and sternum respectively. Mesonotum.—F rom the mesonotum or tergum only the scutellum is exposed dorsally. The rest of the notum is covered by the elytra laterally and is hidden by the pronotum anteriorly. The scutellum.—tThe scutellum (fig. 16, Sct) is a triangular plate, heavily chitinized, covered with short bristles, and externo-anteriorly fused with the prescutum. There occur slight differences in shape in the different species but they are of no importance, NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 35 Scutum.—The scutum (fig. 16, Stu) is represented as two slightly chitinized lobes which are anteriorly fused with the prescutum. The posterior ends are free and lie under the scutellum. A long slender pleural hook (c) originates near the extreme lateral angle. Prescutum—tThe largest area of the mesonotum is occupied by the triangular prescutum (fig. 16, Psc). Externally it forms with the scutellum a smooth continuous plate. The inner side consists of two large and shallow excavations which are surrounded by heavily chitinized ridges. The median ridge is anteriorly divided by two closely placed sutures. Obscure remainders of these sutures are also visible externally and on the scutellum. The extreme anterior corners of the prescutum are produced into two prominent hooks which may correspond to Hopkins’ “ Lateral arm of prephragma and prescutum ” or Korschelt’s “ Zapenfortsatz des Mesonotums,” or Berlese’s “ clavic- ola.” The clavicola (b) is hinged in parts of the pleural claviculas. At a short distance behind the clavicola is a well developed prealar process which embraces the third axillary of the elytra. On the anterior two-thirds of the prescutum, numerous small punctures are visible externally and near the lateral margin occurs a single row of minute hairs. The prephragma and the postscutellum are not represented by sepa- rate plates. Remainders of the former are probably the wide anterior ridge of the prescutum. Mesopleura—The mesopleura are distinctly defined from the ter- gum and sternum. The largest area of each is occupied by the epi- sternum (Eps) which is a strongly chitinized plate, elongate, with the lateral dorsal area smooth and with a fine pubescence on the lateral ventral area. A narrow strip in front of the episternum, which is defined externally by a suture, and a continuation of it towards the ventral posterior angle of the episternum, may represent the preepi- sternum. Dorsally the preepisternum is produced into the clavicolar- disk. Under the ventral half of the episternum projects a narrow plate, the epimeron (Ep). Preepisternum and epimeron are struc- tureless but the latter bears on its posterior margin a row of fine hairs. Mesosternum: Presternum.—A narrow ridgelike plate which is fused with the preepisternum (fig. 16, Pr) of the pleura represents the presternum (Pst). The rest of the sternum is externally defined from this by a suture. Internally the suture is obsolate. Sternum.—The sternum (St) is a rectangular plate with its poste- rior side produced into an angle, externally fused with the sternellar area or intercoxal process (Stl) but internally defined by a suture. The outer surface is smooth and bears a row of bristles and also a few punctures. 30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Sternellar area—vThe sternellar area is strongly produced poste- riorly and internally defined by a suture from the postero-sternellar piece. Poststernellar area.—This piece (Pstr) is a narrow continuation from the sternellar area. Externally both are covered with long bristles. THE METATHORAX Metatergum.—The general appearance and structure is illustrated in figures I, 2 and 3, which also show the two main parts, namely the notum and the postnotum, or pseudonotum, as the postnotum is often called. The latter is well developed and connected with the notum by a transparent membrane (a). The dorsal aspect of the metatergum is shown in figure 17; the inner in figure 19. Metanotum.—The metanotum (figs. 17, 19) is typical in Gnatho- trichus in so far as the prescutum (Psc) is only loosely connected with the scutum (Sct). The connection consists medially of a trans- parent membrane (b); laterally the extreme ends of the posterior prealar process (d) are fused with the lateral margin of the scutular lobes. In this connection it should be mentioned that Hopkins’ pre- scutal lobe seems more likely to be a part of the scutum than of the prescutum. Other modifications are the overlapping of the scutum beyond the posterior prealar process and the development of the scutellum. The metanotum is clearly defined into three transverse divisions which are the prescutum, the scutum and the scutellum. Prescutum.—tThe prescutum (Psc) forms a well developed trans- verse band extending from pleuron to pleuron. Medially it is bent downwards, forming a ventral reflected lobe which may correspond to the prephragma in other insects. A precosta is not present as a plate defined by lines or sculpture. On the level of the interior origin of the anterior apodeme a suture extends interiorly separating the posterior prealar process from the prescutum proper. This process extends laterally, is covered by the scutular lobe and is fused with it at the extreme end. From the antero-lateral corners of the prescu- tum proper originate two prominent hooks, the anterior prealar proc- esses (f). Laterally to the anterior prealar process are two disklike formations on each side (g, h) connected with the posterior prealar process. According to Hopkins, the posterior disk (prescutal disk) serves for the small muscles connecting it with the pleural clavicula. A rather intensive investigation would be necessary to determine the purpose of all these formations and homologize them with similar equivalent parts in other groups. 37 OF GNATHOTRICHUS—SCHEDL MORPHOLOGY sae) NO. ‘ ‘yooy [etauidaysod ‘*' yoo, Burm jerozey ‘t% fumusajsida jo ainqonajys ‘ty fainyns [esouds ‘I6 ‘ysip atojzeuo1d “If {ssaj0id prooeieo ‘ta {ssaoord ayorarjo ‘'p ! umutaqsida jo ap3ue [esjuaA Joliajue ‘19 fainjns [einayd yo yoursq Jori1ajsod ‘tq tainjns [eineajd Jo yoursq Jo1sajue ‘to !yooy Aejndeos ‘4 ‘fuorssaidmr jeisjel ‘b fuoeulsrewma yerayey ‘¢ {yooy jeanayd ‘o ‘uinjoujsod jo yooy svjeoid ‘mw ‘uimpjaynosysod 10 ‘umjoujysod jo a8ptliq aejesid ‘7 ‘ssa00i1d ivjeoid i011ajue ‘f ‘fumsiopopue 40 aulapode uvipsut ‘f fainyns 3e][aynos-0yNos “4 fySIp 1e][a}nNOse1d Jo11a}sod ‘y {ySIP 1e]jaynoseid JolayUe ‘OH faueIquIsW JOIIazUe ‘q faseq BUIM 34} JO Satieyjixe ‘Trp taqo] surm Jol1ajsod ‘7 ‘aytinajdodAy ‘“d¢pyy ‘umnynos “799 ‘tumyjaynos ‘79G fulsA [e}sOOqns ‘IG {MaIA jerpet “y ‘umynosoid ‘9sq ‘aimjns jeinajd ‘gq fwnyoujsod jo eurseiydjsod ‘yd¢y fuoinajdejaw jo uossuidajsod ‘wdag {uinjoujsod jo eysooaid “9g {UIA uURIpeu ‘py fuoInsdejou jo wNutoqsida ‘s¢y {uoinadezut jo uorsuida ‘mdz Su1aa [ezIqno ‘nD ‘ulaA [e}soo ‘7D *“AJAATOodsaI JOadse [e19}e¥] pue Joodse [esiOp ‘uOInaldeyour puUe WINSIoyeJoPY :°997T Susnjas SnYyIAJOYJDUH— LI “DIT Hy } H ‘ ' ; : aie he eB xel+———Isy 38 SMITHSONIAN MISCELLANEOUS COLLECTIONS volt. 82 Scutum.—The largest plate of the metanotum is the scutum ex- tending backward from the anterior membrane (b). The limitation between the scutum and the scutellum, the scuto-scutellar suture, is visible as a ventrally elevated ridge which becomes indistinct laterally. The anterior apodeme divides the scutum in two subdivisions, the scutum proper and the scutular lobes. The latter extend beyond the posterior prealar process of the prescutum as was stated above and cover the process dorsally. Externally the scutum is one continuous half spherical plate medially divided by the scutular groove. In- ternally projections of the scutellum extend far into the scutum. From the inner externo-lateral corners of the scutum proper arise two pairs of parapsidal ridges (k) which converge in a slightly curved line medially. Scutellum.—tThe scutellum, which is posteriorly limited by a mem- brane (a), encloses the scutum in a half circle. The scuto-scutellar suture is produced anteriorly forming the lateral limitations of the scutellar groove. It extends to the anterior margin of the scutum. The space between the produced suture is strongly depressed ex- ternally forming a wide scutellar groove. The posterior end of the mesoscutellum rests in this groove. From the posterior lateral corners of the scutellum arise two armlike formations which converge an- teriorly meeting at about the middle of the scutum. These forma- tions correspond to the endodorsum (Amans), V-shaped ridge (Snod- grass), or median apodeme (Hopkins). Where they join they are connected with the scutellar groove. It is likely that the intensive study of the endodorsum of the Scolytidae will bring out many new features for the systematic arrangement of this group. Postnotum.—The postnotum or pseudonotum is subdivided into three transverse divisions, the precosta (Pc), with the prominent prealar bridges (1) and the postphragma (Pph). The precosta is a simple band separated from the postphragma by the postnotal apodeme. Laterally it is produced into prominent prealar bridges. The inner margin is developed as a heavily chitinized ridge which is posteriorly divided, forming a ring and externally produced into a slender hook, the prealar hook (m). The postphragma is a slightly ventrally bended band. The post- notum is visible externally, giving the appearance of a reduced tergum at the first abdominal segment. Metapleura—The pleuron of the metathorax (fig. 17) consists chiefly of two plates, the episternum (fig. 17, Eps) and the epimeron (Epm). The pleural suture (Ps) is externally represented as a dis- tinct line, internally as a ridgelike structure. From the pleural suture NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 39 branch three other sutures or ridges. Anteriorly there is a short suture dividing the parapterum from the wing process; posterio- dorsally another ridge separates the postepimeron (Pepm) from the rest of the epimeron. Ventrally another ridge indicates that part of the episternum which is covered by the sternum and the metacoxa. Episternum.—The episternum is an externally continuous plate having the shape of a narrow triangle with the base facing forward. Ventro-anteriorly it is produced into a hooklike angle, the sternal hook (c,) or anterior sternal hook of Hopkins. The sternal hook fits into an emargination of the sternum, the clavicula (fig. 18, d). Dorsally the extreme angle of the episternum with the pleural suture (probably also containing elements of the epimeron) is produced into the parapterum (e), or coracoid process, and the wing process, or clavicular process (d). From the underside of the parapterum originates a well-developed pronator, or muscle disk (fig. 17, t:). The episternum is heavily chitinized and covered by numerous large punc- tures which are interlaced by a network of fine ridges. See also fig- ure 17, h,. When the elytra are kept in the closed position the meta- pleura are nearly completely hidden by them. Epimeron.—Between the pleural suture and the lateral margin of the metanotum a more flexible, partly membranous sclerite is in- serted. Posteriorly it is subdivided by a branch of the pleural suture separating the postepimeron from the epimeron proper. While the epimeron proper is more membranous and flexible, the postepimeron is more heavily chitinized. The postepimeron bears dorso-posteriorly a recurved hook, the postepimeral hook (j,), which articulates with the clavicula of the sternum of the first abdominal segments. The hypopleurite (Hpp) extends forward up to a shallow emargination on the dorsal margin of the postepimeron. The anterior margin of the hypopleurite is double reflexed, fitting in a reflexed ridge of the inner layer of the elytra. The area between the anterior margin of the hypopleurite and the dorsal nob of the pleural suture is deeply im- pressed. Epipleurite 1 of the abdomen is situated in front of the hypopleurite closely attached to the scutellum of the postnotum. Metasternum.—tThe metasternum is represented as a rectangular continuous plate divided by remainders of a median line. It is illus- trated in figure 18. The anterior margin is medially produced into an angle which extends far between the mesocoxae. This angle and the thickened anterior margin may correspond to the presternum of other segments. The anterior lateral angles (a) are modified to re- ceive the sternal hooks of the metaepisternae. Therefore these emar- ginations should be called the anterior claviculae of the metasternum. Posteriorly the sternum is infolded producing a narrow plate, the 40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 sternellar area. Normally the sternellar area is hidden by the coxae except for the two prolongations between the coxae. These are bent dorsally, giving the support for and articulation of the furca. The Fic. 18—Gnathotrichus materiarius Fitch: Metasternum, inner aspect. C, coxa; St, sternum; Ji, tibia; Tr, trochanter; a, sternellar area; b, median line; c, pre- sternellar area; d, clavicula; e, sternal hook of metapleuron; t, head of postepimeron. Fic. 19.—Gnathotrichus materiarius Fitch: Metatergum, inner aspect. APh, prephragma; Pc, precosta of postnotum; PN, postnotum; Pph, postphragma; Psc, prescutum; Sct, scutum; Sc/, scutellum; a, posterior membrane; b, anterior membrane; c, scutellar lobe; d, posterior prealar process; e, anterior apodeme; f, anterior prealar process; g, anterior prescutellar disk; h, posterior prescutellar disk; 7, scuto-scutellar suture; 7, median apodeme or endodorsum; k, parapsides; /, prealar bridge of postnotum, or postscutellum; m, prealar hook of postnotum; 7, postnotal apodeme; o, scapular hook. sculpture of the metasternum is minutely rectangulate. The punctures which occur are sparse, the hairs of medium length and more numer- ous laterally. The metathorax shows little specific and no sexual modifications. NO. LO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL AI THE ABDOMEN The chitinous skeleton of the abdomen shows little specific modifica- tion but it bears characters which are of importance in separating the higher groups. The differentiation is mainly in the number of dorsal plates or tergites and the development of the spiculum ventrale in the females. The structure and the relative proportions of the dif- ferent sclerites are illustrated in figures 1, 2, 3, 20, 21, 22, 23, and 24. Dorsal plates or tergites——All the tergites are normally covered by the elytra. In the females seven and in the males eight tergites are well developed. The first six tergites are more or less membranous Fic. 20.—Gunathotrichus materiarius Fitch, male: Abdominal tergites, ventral aspect. I, 2, 3, 4, enlarged sections showing details of structure on the dorsal side; Epp, epipleurites; Epp 7 and 8 fused with tergites; Sp, spiracles; T, tergites. and flexible in both sexes, yellowish in color, and covered with spinous to toothlike armature on the external surface. The spinelike armature is more medial and posterior on the plates. Near the anterior margin the armature becomes more toothlike, forming broad plates armed with minute spines posteriorly (figs. 20, Ti, 2,3,4). These plates near the median line on the second, third and fourth tergites are stouter and not so densely placed. In the same tergites there is a reduction of the chitinization, forming a membranous emargination. Still another type of armature is found on the pleurites as illustrated in figures 20, 4. The purpose of these armatures is doubtful. The in- tersegmental membranes are colorless without any markings. Heavily chitinized bands are situated near the posterior margin of plates two 42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 82 to six. These bands or ridges resemble the parapsides of the meta- thorax both in structure and in position. Punctures are numerous in all the plates and the lateral limitations are always irregular. The seventh and eighth tergites in the males and the seventh in the females are heavily chitinized and lack the above mentioned armature but have numerous hairs and punctures. Lateral plates or pleurites——vThe pleural suture seems to be the line which divides the heavily chitinized hypopleurites from the mem- branous epipleurites. The pleural suture is not visible in the seventh and eighth pleurites because the epipleurite is heavily chitinized here and completely fused with the tergite. The second hypopleurite which Fic. 21.—Gnathotrichus materiarius Fitch: Abdominal sternites, ventral aspect. St, sternites; a, coxal cavity; b, clavicula; c, intercoxal process. extends beyond the postepimerum of the metathorax is ventrally de- fined by a suture while the others are fused ventrally with the sternites. The former corresponds to the second tergite. The hypopleurite be- longing to the first tergite is not represented as a plate but fused with the epipleurite. The hypopleuritic areas are covered by the elytra when they are kept in the closed position, and form a vertical plane, while the sternites make an angle of about 120 degrees with them. As was men- tioned before, the epipleurites are membranous except those which cor- respond to the last tergites. The hypopleurites corresponding to the last seventh and eighth tergites are present only as narrow membranes. Ventral plates or sternites—tIn both sexes only five ventral plates or sternites are distinctly defined by sutures as is illustrated in figure 21 and they represent the sternites three to seven. The sternites are NO: TO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 43 widest at the base, decreasing in width towards the apex. The first visible sternite is the longest and is separated from the second by a suture which is only visible under high magnification. It is very likely that the first visible sternite contains elements of more than one abdominal segment but they are not indicated by sutures or lines. Medially the first sternite is produced into a long process.called the intercoxal process, which extends far between the metacoxae. From Fic. 22.—Gnathotrichus retusus Lec.: Seventh tergite of female. A, dorsal aspect; B, ventral aspect; Spz, seventh spiracle. the base of this process a ridge arises which extends laterally, sepa- rating the part of the sternite covered by the metacoxae from the remainder. At the antero-lateral corners this ridge is developed into a clavicula. In this clavicula (b) articulates the ventral part of the postepimeral hook. The surface of the uncovered part of the first sternite bears numerous hairs which are arranged in concentric rows encircling the metacoxae. Punctures are sparse. All the other ster- nites are separated from each other by deep septae and they have the shape of short rectangular plates of nearly equal length. They are all heavily chitinized and armed with long hairs arranged in a trans- 44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 verse row. The last sternite is infolded on the apex. There occur no striking differences in either different species or in the two sexes. Spiculum ventrale —In the females of all three species the spiculum ventrale is well developed. By careful dissection it can be seen fastened to the Fortsatzlappen Verhoeff. Without any doubt we are dealing here with a true spiculum laterale clausum (Fuchs). The median line commissura, which gives by certain modifications the spiculum ventrale opportum, is especially well defined in Gn. materi- Fic. 23, A.—Gnathotrichus retusus Lec.: Sixth and seventh sternites of a female with the spiculum ventrale. Ca, caput; Coj, conjunctus lateralis; Com, commissura; Br, brachium; Ra, radix; st, sternites, Fic. 23, B.—Gnathotrichus retusus Lec.: Seventh and eighth sternites of a male. arius Fitch and retusus Lec. For further studies on this subject it is proposed to name the different parts of the spiculum. The part where the spiculum joins the seitlichen Ansatzlappen (Verhoeff), seitlichen Lappen (luchs), may be called radix spiculorum ; the more or less chitinized, sometimes membranous bands extending anteriorly, brachium ; and the apically thickened part, caput. The seitlichen Lap- pen (Fuchs), Fortsatzlappen (Verhoeff) should be called the con- junctus lateralis. The spiculum ventralis of Gn. sulcatus Lec. may be easily distinguished from the others by its slimmer brachiae. Gn. retusus Lec. and Gn. materiarius Fitch show no striking differences in this regard. NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 45 THE SPIRACLES Corresponding to the number of the epipleurites, there are eight spiracles in the male and seven in the female. These are implanted in the membranous epipleurites and the apical epipleuro-tergite re- spectively. The eighth pair of spiracles in the male are always rudi- mentary. Gn. materiarius Fitch shows comparatively the best de- velopment in this regard. The seventh epipleurotergite of the female bears a pair of spiracles which are well developed and only very slightly smaller than the others. There also occurs one pair of spiracles on the prothorax. They lie under the produced caudad-lateral angles of the pronotum. Fic. 24.—Spiculum ventrale in female: A, Gnathotrichus sulcatus Lec., B, Gnathotrichus materiarius Fitch. . Br, brachium; Ca, caput; Com, commisura. THE LEGS The three pairs of legs are illustrated in figures 25 and 26. They do not vary strikingly from species to species neither in form nor in sculpture. Therefore the drawings were made from Gnathotrichus materiarius only. The legs present all the typical segments common in Coleoptera, which are the coxa, the trochantin, the femur, the tibia, the tarsus and the pretarsus. Coxva.—The coxa (fig. 25) differs considerably in shape in the three pairs of legs. The coxa of the prothorax (A) is very stout, ball-like, the mesocoxa (B) is slightly longer and the metacoxa (C) is nearly twice as long as the forecoxa. The proximal end of the fore- and mesocoxa show distinct indications of a basicostal suture (a). In the fore-coxa the basicostal suture is formed into an external ridge ventrally, which becomes lower and indistinct laterally. In the meso- coxa a simple suture (a) indicates the limitation of the basicosta. The basicostal area of the forecoxa (Bc) is about twice as long as the same structure in the mesocoxa. The basicoxite (Bex) is present as 46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 a marginal flange and is visible in both the fore- and the mesocoxa. The metacoxa does not show the separation of a basicosta by external lines or internal ridges. The extreme proximal end bears a rather indistinct, internal marginal ridge only. The three articular surfaces (Snodgrass) are largely modified in the different legs. The pleural articular surface of the fore-coxa is present as the medial, proximal margin of the basicosta only. This part is slightly more heavily chitinized. In the mesocoxa the pleural articular surface (b) is more strongly developed. It consists of a Fic. 25.—Guathotrichus materiarius Fitch: A, forecoxa, lateral aspect; B, meso- coxa, C, metacoxa, both ventral aspect. Bc, basicosta; Bcx, basicoxite; F, femur; Fo, fossa; Tr, trochanter; a, basicostal suture; b, pleural articular surface; c, outer ring of fossa; d, inner ring of fossa; e, anterior coxal suture; f, internal ridge; g, basicostal ridge of trochanter; h, condyle of trochanter; 1, trochantero-femoral suture. projection of the basicosta. In the metacoxa a hooklike structure (b), which is basally fused with the anterior coxal suture, may be con- sidered as the pleural articular surface. The articulation of the trochantin is monocondylic with the fossa in the coxa. The fossa (Fo) is a circular, conelike, impression on which two main parts are clearly defined; the outer ring (c) with a ridgelike elevation on the external surface of the coxa and the inner ring (d) or bottom which bears a heavily chitinized knob on the inner surface. It is most probable that the outer ring corresponds to the anterior, the inner ring to the posterior or distal articular surface of Snodgrass. Each coxa has opposite to the fossa a circular opening in NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 47 the heavily chitinized wall of the coxa which is covered by a thin membrane only. The extreme tip of the trochantinal condyle touches this. Ridges to strengthen the coxal walls do not occur in the fore- and mesocoxa. The metacoxa bears such a ridge on the ventral side Fic. 26.—Gnathotrichus materiarius Fitch: A, fore leg, B, mesothoracic leg, C, metathoracic leg. F, femur; Ptar, pretarsus; Tar, tarsus; Ti, tibia; Tr, trochanter; a, trochantero-femoral joint; b, basicostal ridge; c, condyle of trochanter; d, dorsal femoral fossa; e, ventral femoral fossa; f/, anterior groove; g, tibial condyle; h, outer margin of tibia; 7, marginal tooth; j, apical tooth; k, /, m, n, tarsal segments; 0, apical segment; gq, arolium; p, claw. which forms a well developed internal ridge (e); this ridge may correspond to the anterior coxal suture (Snodgrass). Another more feebly developed ridge (f) occurs on the dorsal coxal wall. The hair armature is best explained by the figures. No differences have been found from species to species. 4 48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Trochantin.—The trochantin (fig. 26, Tr) is a small structure and is closely attached to the femur. On the ventral or outer side, when the femur is kept close to the body, a deep groove, the trochantero- femoral groove (a) separates the femur from the trochantin. On the dorsal, or inner side, the separation is indicated by a suture only. Structurally, three parts may be distinguished on the trochantin. These are the basicostal ridge (b), the articulatory condyle (c) and the small apical piece (r). The basicostal ridge is a broad, stuffed, ringlike structure which gives the articulation with the coxa an ex- ternal rest. For the same purpose a hooklike process on the postero- median angle of the basicosta is used. The prominent, cone-shaped articulatory condyle originates basally. The shape of the condyle is alike in all three pairs of legs; the slight differences showing in the plate are due to the different angles from which the drawings were made. The apical piece projects over the basicosta when viewed from above, dorsally, and is fused with the basicosta when seen from below. It bears a long slender spine in all three pairs of legs. The basicosta is externally armed with a few small hairs. From the kind of con- nection between the femur and the trochantin it can be concluded that but little movement is possible between them. Femur.—The femur (fig. 26, F) is the strongest segment of the leg and is about equal in length with the tibia (Ti). Basally it is con- nected with the trochantin; apically, the tibia articulates. The femur is long, oval to rectangular in outline and strongly compressed. The articulation of the tibia is bicondyle (d, e), the femur containing two half circular fossa. There occur no striking differences in the three examined species or in the three pairs of legs in one species. The inner or dorsal surface of the femur is smooth without hairs or bristles ; the exposed surface bears numerous rather fine, long hairs which are directed transversely. A deep groove (f) with two lateral winglike extensions occurs latero-apically. This groove allows the tibia to be flexed closely against the femur. Tibia—The tibia (fig. 26, Ti) is about as long as the femur, tri- angular in outline and strongly compressed anteriorly. The proximal end is widened, half circular in outline, and bears the two articulatory condyles. The proximal quarter of the tibia is slightly bent laterally. The dextral margin is without teeth or armations; the sinistral margin bears four to six low serrations and three marginal teeth (1) which are imbedded in sockets. The apical tooth (j) is straight, rather stout and not imbedded in a socket; the subapical tooth is present as a low elevation only. The articulation of the tarsus is membranous, NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 49 Tarsus.—The tarsus (fig. 26, Tar) is composed of five joints or seg- ments. They are not articulated by hinges with each other but they are movable by means of inflected connecting membranes. The first three segments (k, 1, m) are subequal in length and shape. The basal segment or basitarsus does not show any special armations such as occur in other genera. The fourth segment (n), the smallest of the tarsus, resembles somewhat in shape the trochantin. This segment which is often highly modified in the Scolytidae, is short and knob- like in Gnathotrichus. The apical segment (o) is longer than seg- ments one to three, more slender and slightly curved. Except the fourth, all tarsal segments bear at least a few hairs scattered over the entire length. The third segment also bears a plushlike arrangement of hairs apically. Pretarsus: the terminal segment.—The terminal foot structure (fig. 26, Ptar), which has been called praetarsus, Krallenglied, unguis, ungula and pretarsus by different authors, bears two simple claws (p). The areolium (q) is membranous and heartshaped. THE WINGS As in all the Scolytidae, Gnathotrichus Eichh. has well developed elytra or mesothoracic wings and hind or metathoracic wings. The development of the metathoracic wings would indicate, as has been found to be the case, that the species of this genus are good fliers. No attempt will be made in what follows to speculate on the functions of the different sclerites of the articulation of the wings since the author has had no opportunity to make observations on them. Merely a description of the different parts will be given which it is hoped may be of value for future taxonomic and physiological studies. MESOTHORACIC WINGS OR ELYTRA The mesothoracic wings consist as usual of two layers of integu- ment, both of which are chitinized, the outer layer however being much thicker than the inner layer. The space between these two layers contains the tracheal and circulatory systems. The punctures which mark these wings externally indicate, according to Hopkins, the points of union between the two layers. The form and general structure are shown in figures 1, 3, 16 and 27. The elytra when closed and viewed from above are as wide as or slightly narrower than the pronotum, with the sides subparallel, slightly tapering toward the apex and broadly rounded behind, the extreme external margin subacute. 50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Basal area.—The basal area (fig. 29), as here interpreted, is the basal part of the elytra itself and the sclerites which form the con- nection with mesonotum and the mesopleura respectively. The articu- latory elements of the elytra itself are made up chiefly of the pro- jected costa (Co) and subcostal veins (Sco) and the costal (a) and the subcostal heads (b). These heads articulate with the mesopleural clavicola (fig. 16, d). There are also four distinct axillaries (fig. 29, aX; to ax,) or pteraliae. The first axillary (ax,) partly encloses Fic. 27.—Gnathotrichus retusus Lec.: Left elytron, ventral aspect. An, anal; Cu, cubitus; Me, media; Ra, radius; Sc, subcosta; W1/, lateral wing lock; a, dorsal or sutural margin; b, costal margin; c, lateral convexity; d, stridulating scraper; é, apex. the tegula and fuses at its apex with the second axillary. The second axillary (ax) articulates at its base with the prealar process (a) of the prescutum. The apex of the second axillary forms a heavily chitinized clamp in which the elytra fits as a tongue. The third axillary (ax;) corresponds to Hopkins’ flexor plate. It commences on the internal surface of the second axillary and ends on the external surface of the elytra. It is believed that a sclerite (ax,) projecting from the posterior margin of the tegula is the fourth axillary. The tegula (Te) is well developed, having the form of a hairy pad. — NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL SI Tracheation—All six primary veins (fig. 27) are present and these run roughly parallel and equidistant from each other the whole length of the wing. The costal vein is fused with the corrugated and thickened anterior margin (b) forming an anterior ligature of the wing. The subcostal (Sc), medial (Me), cubital (Cu) and anal veins (An) are simple ; the radius is split into two branches (Ra,, Ra.). The finer divisions of the tracheae permeate the spaces between the veins producing a fine network. Between the adjacent veins there are situ- ated two fairly well defined rows of punctures. Sculpture and vestiture —The occurring punctures are as previously mentioned arranged in approximate rows, being more confused A i Fic. 28.—Gnathotrichus materiarius Fitch: Mandibles of the larva. a, apical tooth; b, subapical tooth; c, median tooth; d, molar tooth; e, lateral bristle, or seta (seta mandibulae lateralis); f;~», dorsal setae, or bristles (seta mandibulae lateralis) ; g, retractor tendon; gi, extensor tendon; /:, retractor disk; 7, extensor disk. laterally and on the declivity. The interspaces are minutely recticu- late and punctulate and in all three species about alike. From the punctures originate minute hairs which are slightly longer on the declivity. There also occur longer bristles but they are scarce and scattered over the entire surface, being more numerous on the declivity. Lateral wing lock—On the inner lateral side of the elytra at the level of the anterior margin of the hypopleura a short transverse ridge (fig. 27, W1) is situated. That ridge is recurved, fitting into a similar formation which is formed by the anterior margin of the hypopleura (fig. 1, f, fig. 17, i,). These two parts interlock and are apparently intended to keep the elytra closed. Declivity—The extreme lateral margin of the elytra is subacute. The declivity itself is sloping with a more or less distinct sulcus on 52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 each side of the median suture. The lateral convexities (fig. 27, c) bear at least faint traces of granules from which bristles arise. There also occur a few bristles near the apex of the declivity. Stridulating accessories—In both sexes the left elytron bears on the declivity a well developed lobe which lies under the right elytron Deere Prescutum \ ie sae Fig, 29.—Gnathotrichus retusus Lec.: A, articulation of the elytra, ventral as- pect; B, stridulating apparatus on the apex of the elytra, ventral aspect. Cal, callus; Co, costal ridge; Sco, subcostal vein; Te, tegula; a, costal head; b, subcostal head, ax1, @%2, aX, axs, the axillaries; c, lateral arm of prephragma Hopk., or pleural hook of scutum; d, prealar process; e, stridulating rasp; f, stridulating scraper. when the elytra are kept in the closed position. This lobe, the stridu- latory scraper (fig. 27 d, fig. 29 f) is finely transversely sulcate on the dorsal side. The corresponding area on the right elytron (fig. 29, c) is also rasplike but only on a narrow strip. If these two parts are grated against each other, it is most probable that they will produce a chirping sound. Up to date this sound has not been heard by the NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 53 author and therefore this statement is merely an attempt to explain these two parts of the elytra. Specific modifications of the elytra——While Gnathotrichus shows the strongest development of the declival sulci, with lateral convexities and granules on the latter, these characters decrease in development in Gn. sulcatus Lec. and are faint in Gn. materiarius Fitch. There also octur many variations from specimen to specimen so a determination cannot be based on these characters only. METATHORACIC WINGS OR HIND WINGS The metathoracic wings (figs. 3, 17) are homologous with the meso- thoracic wings but differ considerably in structure and development due to their use as flying apparatus. In the genus Gnathotrichus Eichh. no specific modifications of importance have been observed. As in all genera of this family the wings are folded together and covered by the elytra when the beetles are at rest. The hind wings are twice as long as the elytra and three times as long as wide. Near the base on the inner side occurs a deep emargination separating a distinct lobe from the wing—the posterior wing lobe (fig. 3, WL, 17, LL). The shape of the wings is very much alike in all three species, long oval with the anterior and posterior margins nearly parallel. The wings consist of two layers of integument enclosing the tracheal system. In the hind wings both of these layers are membranous ex- cept on the veins and the basal sclerites. Externally they are covered with microscopic hairs, except on the basal heavy parts of the veins and the axillaries (fig. 17). V eins—The venation of the wings shows considerable reduction. The only visible veins are the costa (fig. 3, Co), subcosta (Sco), radius (Ri+R.2), media (Mi, Mz) and cubitus (Cu,). The radial and the medial veins are split into two branches. Costa——As Hopkins has shown for the genus Dendroctonus, the costal vein (fig. 3, Co, 17, C) is also in Gnathotrichus Eichh. confined to a short basal piece. Apically it does not join another vein but is reduced so that the costal margin is occupied by a membrane only up to the point where the radial vein is bent forward and structurally replaces the costa. The base of the costa is produced into the so-called costal head (fig. 30, CoH). It consists of two parts, the costal condyle (fig. 30, a), and the costal pocket (b). The former articulates with the clavicle process of the metaepisternum (fig. 17, d,). From the base of the costal condyle a pocket stretches to the subcosta. At about the center of the pocket a projection of the subcostal head, the sub- 54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82 costal hinge (fig. 30, c), is attached by tendons giving the motion of a hinge joint. This attachment enables the subcostal head to move in the pocket. Subcosta—The subcosta (figs. 3, Sco, 17, Sc, 30, Sco) consists of a chitinous band extending apically as far as the costa and strengthened by two ridges of dense chitin. The basal part, or subcostal head (fig. 30, ScoH), as it was called by Hopkins, is anteriorly formed into a S00 Go Fic. 30.—Gnathotrichus retusus Lec.: Basal area of the wing, wing articulation. Co, costal vein; CoH, costal head; Cu, cubital vein; Me, medial vein; Sco, subcostal vein; ScoH, subcostal head; az, axillary plates; a, costal condyle; 6, costal pocket; c, subcostal hinge; d, subcostal labrum; e, condyle of first axillary; f, subcostal fossa; 9, membranous fold connecting Me and ars; h, membranous fold connecting Me and Cu; 1, membranous fold connecting Cu and azz; j, epicondyle of ax; k, scapula arm; /, axillary horn; m, axilla; n, anterior process of azz; 0, articulatory margin; 9, scapular hook of prescutum; q, apical margin; r¢, lateral groove; s, axillary tendon; t, uw, lateral emarginations; v, posterior part, or handle; w, anterior part, or blade. projection which is composed of a circular band of chitin (fig. 30, c), articulating with the costal pocket. The posterior part forms a fossa, the subcostal fossa (f), which articulates with the condyle (e) of the first axillary. The labrum (d) of the fossa is deeper on the outer side than on the inner. The outer side of the labrum is divided at its free edge by a V shaped groove. Radius.—The radius (figs. 3, R, Ri, Re, 17 R) is not directly fused with any of the axillary plates but is basally closely connected with the subcosta. From the point of fusion with the subcosta the radius NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 55 extends to the folding hinge on the wing gradually increasing in width. The anterior border of the radius becomes the anterior border of the wing just after the reduction of the costa and subcosta. The folding hinge occurs as a V-shaped plate, the point of the V being anterior. From the folding hinge the radius is divided into two branches (R, and R,). Radius 1 extends as a broad chitinous band along the anterior border of the wing to its apex gradually diminishing in width. Radius 2 is slightly narrower than R,, running two-thirds with, and parallel to it. Media—The media (figs. 3, M, 17, M and 30, Me) is connected to axillary four (fig. 30, ax,) by a membranous fold (g) of L shape. Another fold (h) runs posteriorly to the cubitus (Cu). From the base to the level of the folding hinge it is continued as a single vein. At the latter point it is divided into two branches (fig. 3, Mi and M2), both of which extend to the anal margin. The connection between the single basal part of the media and M, is membranous, while M, is a direct continuation of the former. Cubitus—The cubitus (figs. 3, Cu, 17, Cu and 30, Cu) is con- nected with axillary three (fig. 30, ax,;) by a membranous fold (1) which runs from the base of the cubitus anteriorly. From its base the cubitus proceeds toward the anal margin which it does not reach. No other branches of the cubitus nor an anal vein are present. Wing articulation—The articulation of the wings (figs. 3, 17 and 30) is brought about by means of the costal and subcostal heads, the axillaries of the wings, the clavicle and coracoid process of the meta- episternum, the scapular hook of the posterior prealar process of the prescutum and a series of muscles and tendons connecting and moving these parts. The connection of the costa and subcosta to each other and the costa with the metapleuron was discussed before. In the following lines the axillaries and their connection with the meta- tergum and metapleuron will be explained. The axillaries are chitinous plates, differing in number in the dif- ferent orders and also it seems in the genera of the Scolytoidea, which function as articulatory accessories. In the genus Gnathotrichus Eichh. four of such plates are distinctly developed. The heads of the costal and subcostal veins are here not counted as axillaries because they are fused with the veins in such a way that separations seem unnecessary. First axillary —The first axillary (fig. 30, ax,) or scapular plate, as it was called by Hopkins, is very similar in shape to that of Den- droctonus valens Lec. as it was illustrated by Hopkins. Anteriorly it is produced to a condyle (e) with a distinct epicondyle (j), articulat- 56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 ing with the fossae (d) of the subcosta. The slender part posterior to the condyle, which was called the scapular arm by Hopkins (k), bears a hornlike process (1), the axillary horn. The horn forms with the scapular arm an axilla (m) in which the anterior process (n) of the second axillary rests. The margin towards the notum or articu- latory margin (Hopkins) (0) is connected with the posterior prealar process of the prescutum by the scapular hook (p) and tendons. The scapular hook is a heavily chitinized hooklike plate on the lateral margin of the prealar process. The margin towards the apex (q) of the wing fits into the lateral groove (r) of the second axillary. The base of the scapular plate is deeply emarginated. Second axillary—vThe second axillary (fig. 30, ax.) or subscapular plate has the shape of an equilateral triangle with its base anteriorly. The side towards the first axillary bears a deep groove, the lateral groove (r), which encloses the apical margin of the first axillary (q). With axillary four it is connected by a membrane only while a well developed tendon (s) connects axillaries two and three on its pos- terior end. By means of this tendon a strong connection is brought about from the posterior prealar process to the first, second and third axillaries. Third axillary—rThe third axillary (fig. 30, ax3) or flexor plate (Hopkins) has the shape of a sickle with two emarginations (t, u) on its inner side. The anterior one (t) ends in the tendon connecting axillaries two and three. The handle of the sicklelike plate (v) is without special characters. The blade (w) shows on its posterior margin near the apex a membranous fold (1) connecting this plate with the cubital vein. Fourth axillary—The median plate (Hopkins) corresponds to the fourth axillary (fig. 30, ax,). It is triangular in shape, connected to the median vein by a membranous fold (g) and to the other axil- laries by membranes only. When the radial plate (Hopkins) is not considered as a distinct plate but as a connecting tendon between the second axillary and the radial vein only, the shape and structure of the other axillaries are very much alike in the widely separated genera Dendroctonus Er. and Gnathotrichus Eichh. Further studies will show if this means a parallel modification or if we have to deal with a character common to the superfamily of the Scolytoidea. Lateral impression—An area distinctly impressed on the meta- scutum (fig. 17, q), according to Hopkins, accommodates the flexor plate at rest when the wings are closed. NO. I0 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 57 Lateral emargination.—The lateral emargination (Hopkins) (fig. 17, p) is an emargination on the scutum on the lateral margin of the scutellar lobe in which is implanted the inner posterior lobe of the scapular plate and the scapular hook. The latter connects the pos- terior prealar process with the scapular plate and the scutellar lobe, respectively. Tue Mare REPRODUCTIVE ORGANS The male reproductive organs consist, as shown by Nuesslin for this family, of elements of endodermal and of ectodermal origin. These two groups of elements are separated in the larvae and be- come connected during the pupal stage. Of endodermal origin are the testi (fig. 31, Te), the vasa deferentia (fig. 31, Vd) and the Fic. 31.—Gnathotrichus materiarius Fitch: Male reproductive organs. Dej, ductus ejaculatorius; Gl. acc, accessory glands; Pen, penis; Te, testi; Vd-d, vasa deferentia, duplex; Vd-s, vasa deferentia, simplex. mesadenic, or mucous glands (fig. 31, Gl. acc). On the other hand, the seminal vesicle (in part, fig. 33, Rec.), the ductus ejaculatorius (fig. 31, Dej) and the penis (fig. 3, Pen) are of ectodermal origin. The point of connection of these elements is plainly visible in the adults. The distal part of the vasa deferentia and the mucous glands join a short, usually narrow tube, ‘“ Zunge’’ (Nuesslin) ; the latter connects with the ductus ejaculatorius. Externally the Zunge, an endodermal structure, is encircled by a wider tubelike or sphericle envelope, which consists of two parts, the distal end or “ Mantel’? (Nuesslin) of en- dodermal, and the basal part or “ Becher” (Nuesslin) of ectodermal origin. These last mentioned structures are seen commonly as a ball- like widening of the ductus ejaculatorius and are usually called the seminal vesicle. The following description is based on -Gnathotrichus materiarius Fitch only. 58 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 The testes consist of two oval structures which are closely connected medially. The vasa deferentia is Y shaped. The mucous glands are wide and stout and about as long as the testi. The seminal vesicle is represented by a subsphericle structure to the upper side of which the glands are joined. The ductus ejaculatorius is comparatively short, stout, and as long as the testi. In Nuesslin’s key to the larger groups of Scolytidae, based on the male reproductive organs except the penis, Gnathotrichus falls near to the Ernoporinae. Penis.—In order to consider the penis of Gnathotrichus, it is first necessary to discuss in a general way the Scolytid penis. Lindeman, who was the first investigator of the S colytid penis, dis- tinguished two main groups of elements, the primary and the acces- sory. He states that the primary elements, which comprise the body (Koerper), the fork (Gabel) and the stalk (Stengel), are constant throughout the family Scolytidae, while the accessory elements, which form together the so-called Aufsatz, vary considerably in the dif- ferent genera as well as from species to species in one genus. Ver- hoeff, the second to deal with the subject, did not agree with this classification, while Nuesslin supported Lindeman’s opinion. The last of the more important investigators of the Scolytid penis, Dr. Fuchs, constructed a new system for such a classification, without consideration of the phylogeny, and distinguished covers (Huellen), inclosed parts and parts external to the covers. The author cannot agree with Lindeman and Nuesslin that the primary elements always included in the Scolytid penis consist of the fork (parameren Ver- hoeff) and the stalk (spiculum ventrale (Fuchs)). Already Fuchs has shown how far the reduction of the parameren and the spiculum ventrale in the European Hylesinidae has gone and the author is con- vinced that more intensive investigations of this subject will bring up many new facts. Without doubt more than three-quarters of the genera and ninety per cent of the species of the Scolytidae have not been studied at all or not thoroughly enough. For example, it was found in the present study that the spiculum ventrale is absent in Gnathotrichus, and it will not be long until genera are found in which the complete loss of the parameren occurs. If it is desirable to dis- tinguish between primary and accessory elements, the author would prefer that the primary elements be considered the body only, the accessory elements all the parts outside of it. For further studies of this subject, the author will adopt Dr. Fuchs’ classification and nomen- clature until a time when sufficient new material is available to fur- nish new conclusions. NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 59 The penis presents, in the genus Gnathotrichus, excellent generic as well as specific characters. The following discussion is based on slides which were made from dried material treated with 10% sodium- hydroxide solution. Dr. Fuchs distinguished two layers of covers, the outer and the inner. These two layers were also found to be present in Gnathotrichus. The outer layer consists of a membranous tube Fic. 32—A, Gnathotrichus sulcatus Lec.; B, Gnathotrichus retusus Lec.; C, D, Gnathotrichus materiarius Fitch.: A, B, C, lateral aspect; D, dorsal aspect. Ca, caput; Fep, femora penis; Lad, laminae dorsales; Lav, laminae ventrales; Me, metula; Pal, pallidium; Pa, parameren; Prp, preputial sac; Ro, rostrum; a, ventral nob of the parameren; b, tegmen furcae; c, internal ridge on Lad. in which the inner cover slides forward and backward. A ringlike part of this tube is heavily chitinized, and when dried specimens are used only this structure is obtained. It was called by Lindeman the gabel, the parameren by Verhoeff and the tegmen by Hopkins. The inner cover consists of a second tube which is heavily chitinized throughout and which shows remarkable variations from species to species. Figure 32 illustrates the peni of the genus under exami- nation. 60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 Parameren.—In Gnathotrichus the parameren (Pa) is a heavily chitinized ringlike structure. It is entire, without a dorsal transverse suture or knoblike projection cephalad, as in Pityogenes Bedel, and was called umbellicus by Fuchs. Ventrally, a faint suture is visible in Gn. sulcatus Lec. and retusus Lec. only. A prominent, heavily chiti- nized hook extends cephalad from the ventral suture. This structure was called the metula (Me) by Fuchs and the apodemal process by Hopkins. In Gn. retusus Lec. and sulcatus Lec. a second, caudad, but much smaller knob (a) is present. The tegmen furcae (Fuchs) (b), which are a lateral continuation of the metula, are weakly de- veloped. Lateral widenings of the parameren, Seitenfluegel (Fuchs), are absent. Specific modifications :— A—Parameren without small knob ventro-caudad; metula long but slender. Gn. materiarius Fitch. AA—Parameren with small knob ventro-caudad; metula variously modified. B—Metula short, weakly developed. Gn. retusus Lec. BB—Metula long, strongly developed. Gn. sulcatus Lec. Inner covers—The inner cover (Fuchs), the body (Hopkins), the penis tube (Nuesslin) is a tubelike structure, bilateral-symmetric. On the inner covers three main parts may be distinguished which are the lamina dorsales (Lad), the laminae ventrales (Lav) and the peduculi penis (Fep). The dorso-caudad portion of the inner covers was called the Endplatten by Lindeman, the laminae dorsales by Fuchs and the dorsal plates by Hopkins. The laminae ventrales (Fuchs) or ventral plates (Hopkins) are the corresponding ventral portion of the laminae dorsales. In the genera Pityogenes Bedel, Ips de Geer, Pityokteines Fuchs, Neothomicus Fuchs, and others, the laminae dorsales and ven- trales are largely separated by deep emarginations caudad giving the laminae the shape of four free projections which are connected basally only. The basal, fused, entire part of the laminae ventrales is the pallidium (Fuchs (Pal)). The sometimes narrow band connecting the two dorsal plates is the jugum or Steg (Fuchs). In Gnathotrichus the laminae dorsales and ventrales are fused laterally. Dorsally, the two laminae dorsales are separated by an obscure suture only. The laminae ventrales are fused ventrally, open on the extreme caudad portion. The laminae dorsales as well as the laminae ventrales bear numerous sensory pores on the caudad half. The latter is strengthened by a stronger chitinized band, the caudad limitation of which (c) is strongly emarginate. This chitinous strengthening was called the NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 61 radius by Fuchs and this is well developed in all three species of Gnathotrichus. A corresponding strengthening on the laminae dor- sales, which as the manubrium (Fuchs) is well developed in the genus Pityogenes is obscure in Gnathotrichus. The caudad portion of the laminae ventrales, the caput (Fuchs), is variously modified, sometimes bearing a beaklike projection dorsally which was called the rostrum by Fuchs. The caput and rostrum vary considerably in shape and de- velopment in the genus Gnathotrichus. The area of the pallidium, from which the peduculi penis originate, the radix (Fuchs), is not characterized by a heavier chitinization. The peduculi penis were also called Fuesschen by Lindeman, femora penis by Verhoeff and body apodemes by Hopkins. In the normal position the peduculi penis are parallel; when mounted on slides they usually cross each other. Cephalad the peduculi are slightly widened, their connection with the pallidium is solid, not hingelike. Enclosed parts-——The enclosed parts are a short part of the ductus ejaculatorius, the preputial sac and chitinous strengthenings of the latter. The ductus ejaculatorius is easily recognized by its enclosing muscle structure. The author was able to trace this structure as far caudad as the radius (c) extends. The preputial sac (Prp) consists of a colorless membrane without any chitinous strengthenings. It seems to be connected with the ductus ejaculatorius at the anterior emargination of the radius. Chitinous structures such as the Rinne (Fuchs) do not occur in the genus Gnathotrichus. Parts outside of the covers——It was stated in the introduction to the discussion of the penis that no indications of the spiculum ventrale are present in the genus Gnathotrichus. While in Xyloterus Er. and in some genera of the European Hylesinidac, the reduction of the Rinne (Fuchs) mostly is followed by a stronger development of the spicu- lum ventrale, Gnathotrichus presents a complete reduction of both. Generic characters of the penis—Spiculum ventrale absent; para- meren an entire ring, metula well developed; laminae dorsales and ventrales fused laterally, the laminae dorsales dorsally separated by an obscure suture, the laminae ventrales fused except on the extreme caudad portion, the laminae forming a tube, radius distinct, manu- brium obscure, jugum and pallidium not clearly defined ; sensory pores on the caudad half of the laminae dorsally as well as on the laminae ventrales ; the latter always extending farther caudad than the former ; the peduculi penis slender, slightly widened cephalad, about as long as the laminae dorsales, connection with the pallidium solid not hinge- like; Rinne absent, preputial sac about as long as half of the laminae ventrales. 62 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 In the classification of the Scolytidae, based on the chitinous skele- ton of the penis by Nuesslin, Gnathotrichus would have been in con- trast to all the other genera. This is easily explained by the fact that only this one character was used in placing the genera. The author has no reason to believe that Gnathotrichus is not a highly specialized genus of the Pityophthorinae. Specific modifications :-— A—Parameren without ventro-caudad knob, metula long but slender ; laminae dorsales with their dorsal margin straight, the dorso- caudad angle obtuse and broadly rounded, the posterior mar- gin is directed ventro-caudad from this angle; the laminae ventrales with their ventral margin straight, only slightly projecting caudad farther than the laminae dorsales, caput weakly developed, nearly in line with the dorso-caudad mar- gin of the laminae dorsales, rostrum obsolate ; peduculi penis about as long as the laminae ventrales, very slender, only very slightly widened at the cephalad end, basal part narrow. Gn. materiarius Fitch. AA—Parameren with ventro-caudad knob opposite the metula, the latter variously modified; laminae dorsales with the dorsal margin broadly arcuate, the dorso-caudad angle variously modified either slightly acute but rather broadly rounded or almost evenly arcuate with the dorsal margin of the laminae dorsales; the laminae ventrales with their ventral margin distinctly incurved, much farther projecting caudad than the laminae dorsales, caput strongly developed, rostrum distinct ; peduculi penes vary in length, stouter, more strongly widened at the cephalad end, basal part distinctly widened. B—Metula short, weakly developed ; the dorso-caudad angle slightly acute but rather broadly rounded, the pos- terior margin is directed ventro-cephalad from this angle, caput not evenly rounded caudad, more tube- like, ventro-caudad margin oblique, the dorsal angle of the rostrum extending to about half of the width of the combined laminae dorsales and ven- trales, between the cephalad margin of the rostrum and the caudad margin of the laminae dorsales, a wide, rectangular space membranous; peduculi penis as long as the laminae dorsales on the dorsal margin. Gn. retusus Lec. NGOS YO) MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 63 BB—Metula long, strongly developed; the lamina dorsales with their posterior and caudad margin almost evenly rounded throughout ; caput evenly rounded caudad, half sphericle, the membranous space be- tween the cephalad margin of the rostrum and the caudad margin of the laminae dorsales narrow, slitlike, the dorso-cephalad angle of the rostrum and the dorso-caudad angle of the laminae dorsales in one level; peduculi penis distinctly longer than the laminae dorsales. Gn. sulcatus Lec. THE FEMALE REPRODUCTIVE ORGANS The female reproductive organs (fig. 33) were examined from Gn. materiarius Fitch only. As in all Rhychophora, two pairs of Fic. 33.—Gnathotrichus materiarius Fitch.: Female reproductive organs. A, the complete organs: B, receptaculum seminis; Ceg, cement glands; Ov, ovaries; OvD, paired oviducts; Ree, receptaculum seminis; Tc8, eight tergites, reduced; Spg, spermathecal gland; Spv, spiculum ventrale; Vag. vagina. ovaries (Ov) are present which are connected distally. The paired oviducts (OvD) are short and stout. Fhe vagina (Vag) is distinctly shorter than the ovaries. Near the basal end of the latter two cement glands (Ceg) originate. They are rather weakly developed, short and ball-like in outline. A bursa copulatrix is not present. The re- ceptaculum seminis (Rec) originates from the vagina at about the 5 64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 same level as the cement glands; it has the shape of a pipe and bears on its distal end the spermathecal gland (Spg). The receptaculum was examined in all three species but no differences have been found. In the classification of the Scolytidae, based on the female repro- ductive organs by Nuesslin, Gnathotrichus would fall in a group to- gether with the genus Thamnurgus Eichhoff. THe ALIMENTARY CANAL The alimentary canal was fully investigated in Gn. materiarius Fitch, the proventriculus in Gu. retusus Lec. and sulcatus Lec., also. The whole alimentary canal of Gnathotrichus is illustrated in figure 34, the proventriculus in figure 35. The alimentary canal is a tube extending from one end of the body to the other. As in most of the mandibulary insects, three main divisions are clearly defined. These are termed the fore, mid, and hind intestine (fig. 34, A, B, C). The ectodermal origin of the fore- and hind intestine are well illustrated by the occurring chitinizations. Fore-intestine —On the fore-intestine the following consecutive divisions are well defined: The Pharynx ( ?), Oesophagus (Oes), Crop (Cr), and the proventriculus (Pve). The well developed proven- tricula are the characteristicum of the adults. The pharynx is not distinctly defined from the mouth cavity. The oesphagus is about as long as the crop and the proventriculus united. It consists of a simple tube, widened distally where it gradu- ally passes over to the crop. The strongly widened tube situated apically of the proventriculus may be designated as the crop. Proventriculus—The proventriculus is a highly specialized organ in which the food is prepared before it enters the more delicate ventric- ulus. The characteristic features of the proventriculus are a remarka- ble development of the chitinous intima into folds and teeth and a considerable increase of the size and development of the muscles of this region. On account of the importance of the proventriculus as a taxonomical characteristicum and of the general morphological in- terest of this structure, a more detailed discussion seems to be necessary. Lindeman, who was the first investigator of the Scolytid proven- triculus, distinguished two main parts or longitudinal divisions. The anterior part he called the Sack, the posterior, or caudad part, the Kaumagen. Nuesslin and Fuchs followed Lindeman’s nomenclature. The Sack (Lindeman) corresponds to the crop (Hopkins) and forms the intermediate part between the oesophagus and the Kaumagen (Lindeman). Hopkins used the term proventriculus for the Kau- NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 65 Fic. 34.—Gnathotrichus materiarius Fitch: Adult, alimentary canal and its appendages. A, fore intestine; B, mid-intestine; C, hind-intestine; Cr, crop; Mav, malpighian vessels; Oes, oesophagus; Pve, proventriculus; Re, rectum; Ve, ventriculus; a, large intestine; b, posterior tube of the mid-intestine; c, small intestine. Fic. 35.—Gnathotrichus materiarius Fitch: Proventriculus. a, median line; 6, sutural teeth; c, anterior closing teeth; d, dentation of masticatory teeth, all together, masticatory brush; e, femora of the masticatory teeth, Abdachungszaehne (Nuesslin); #, posterior closing teeth; A, masticatory plate; B, anterior plate. 66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 magen (Lindeman) only. In the following discussion the interpreta- tions of Hopkins of the terms crop and proventriculus are used. The proventriculus consists of eight plates arranged to form a tube, as illustrated in figure 35. On each plate two longitudinal divi- sions are clearly defined. Lindeman called the cephalad part the Plat- tenteil (A), the caudad part the Ladenteil (B) ; the corresponding terms of Hopkins are anterior plate and posterior or masticatory plate. The latter terms are adopted in this paper. In Gnathotrichus, both of these plates are divided by a median suture (a) which is dis- tinctly visible on the masticatory plate and indicated by a row of bristles (b) on the anterior plate. These bristles, which are of taxo- nomic importance, have been called Zaehne am medianen Kauplatten- rand by Nuesslin and sutural teeth by Hopkins. In Gnathotrichus they are present as slender, sharply pointed, and simple bristles. The anterior plate is not quite one-sixth as long as the whole proventriculus. The masticatory plate (A) bears a symmetrical arrangement of teeth which presents the true chewing apparatus of the proventriculus. On each tooth two elements are clearly defined, the instep and the den- tation. The totality of the insteps corresponds to the Abdachung (c) ; that of all dentations to the Buerste (a) of the German authors. Hop- kins called the first mentioned the femora of the masticatory teeth, the latter the masticatory brush. The masticatory teeth are all similar in shape and very numerous in the genus Gnathotrichus. Cephalad, they are bordered by a few (8-12) longer teeth (c) which differ greatly in shape and which are directed toward the center of the proventriculus. These teeth are apparently intended to regulate the entering of the food. They have been called Sperrborsten by Nuess- lin and closing teeth by Hopkins. To distinguish them from a similar arrangement of teeth which occur in Gnathotrichus and other genera on the caudad end of the masticatory plate ({) it is proposed to call the former cephalad closing teeth, the latter caudad closing teeth. In Gnathotrichus, the following armatures are not present : (a) Hackenzaehne (Nuesslin), or apical teeth of the anterior plate; the designation of a row of short, often curved teeth on the apical margin of the anterior plate. (b) Ersatzperrborsten (Nuesslin), marginal bristles or marginal fringe (Hopkins) ; a longitudinal row of bristles along the lateral margin of the anterior plate. (c) Kreuzlinie (Nuesslin), a row of short, stout teeth arising from the lateral margin of the anterior plate and converging pos- teriorly. NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 67 (d) Abdachungszaehne (Nuesslin), masticatory teeth which have two dentations, one, the totality of all composing the mastica- tory brush, and a second smaller tooth on the instep, the totality of which forms a second brush consisting of a single row of teeth only. In the classification of the Scolytidae based on the proventriculus, Gnathotrichus should be placed with Xyleterus Er., Xyleborus Eichh., Anisandrus Ferr. and other ambrosia beetles together in one group. There is little doubt that the similarity of the digestive systems in ambrosia beetles of the Superfamily Scolytoidea is of no importance in the classification. These are merely parallel] modifications of groups deriving from very different ancestors. The proventriculus is very similar in all three species of Guathotri- chus and it is not possible to distinguish them by characters of this part. Mid-intestine —The mid-intestine is about one-third of the whole length of the alimentary canal. According to Nuesslin the proportions are the same as in Amsandrus dispar Fabr. and Xyloterus lineatus Oliv. In Gnathotrichus two subdivisions of the mid-intestines are well defined. The anterior part, which presents the widest part of the whole alimentary canal, has the form of a ball and is covered with short, half spherical gastric coeca. This part is here designated as the ven- triculus proper. The posterior, much narrower tubelike part, is here called the posterior tube of the mid-intestine. It bears much smaller gastric coeca which distinctly decrease in size toward the origin of the Malpighian vessels and which are always more filiform in shape. The origin of the Malpighian vessels marks the posterior limit of the mid-intestine. These are rather narrow, long tubelike vessels, strongly entangled around the posterior part of the mid-intestine and do not vary noticeably in size. Hind-intestine —While the fore- and mid-intestine are situated as a straight tube in the body, the hind intestine forms a distinct loop. The latter does not bear any gastric coeca but is characterized by the muscles which enclose it. The subdivisions, the small and large in- testine and the rectum, are not so clearly separated. The ovaries of the female reproductive organs are always situated above the hind intestine ; the testi of the male lie under and ventral to it. THE LARVAE On account of the difficulty in getting material of the western species, the following discussion is based on Gnathotrichus materiarius Fitch only. VOL. 82 SMITHSONIAN MISCELLANEOUS COLLECTIONS 68 ~ND__ Fi I ' e-—N ane ee are Ne MORPHOLOGY OF GNATHOTRICHUS—SCHEDL Io NO. ‘sajoeiids ‘ds {1[eo Joo} ‘y fstjeue ejoS ‘JUIUISas [PUB UO VEJaS OM} “F—TH SyudUTSoS [RUB ‘saqo] [Bue ‘6B $gQ Juausas euruopqe uo vyzas auo ‘Tf $6 jUauIZas [eUTWIOpqe UO aejas aa14} “P~TY{ ! £-1 syusuIdaS [eUIWOpqe UO oRJaS OM} “S—Tf fE-1 sjUsWIseS 910e10Y4} UO avjas inoj ‘If {1ynosovid vas ‘aze[d [eynosaad ‘f $6 yuouIZas [eUIWIOpqe uO vyas aUO ‘Ta fg JUaUIBOS [eUTWIOpge UO 9BIaS OM} “S—Ta ¢Z-1 SjUuaUIdAS jeulmopqe pue ‘Z pue I S}UauIZIS d10e104} UO aR}aS INO} ‘Fla FI JUDWISS D1I9e10Y} UO seZIS aay} “PFA SI[N}NoS vy—as ‘aze[d [ejnos Ie][aynNos ‘9 ‘Z-1 syuaulSas [eulMOpge uo arjas OM} ‘Tp {€ pue z sjuatudas O19R10Y4} UO eyaS JU ‘Tp fjUaUBaS dIOvIOY} JsIy pue ‘6 pue g §}UaWIdaS eulwopqe uo ovjas 99143 “Tp Sumorinaydida eyes ‘azerd [eanaydide ‘p ‘yuauises [eurMOpqe YyUIU jo opInojdodAy uo vjas auo ‘TI :S}UoUIsaS [eulWmopqe qjUIU pue 4yYsI9 JO aziimajdodAy uo avzas 9014} “PTD ‘sjusl sas 910e104} Ply} Pue puodasS jo apansijdodAy uo aejas Inojy ‘FT :Z-I syuauIZas [eUIWIOpge pur jusUIsas o19eI10Y} Isy JO aznafdoddy uo aeyzes OM} %-T9 SumMorIInajdoddy vzas ‘ayejd Jeanajdoddy ‘9 {6-1 sj}uoUr -3as [eUIWIOpqe ay} UO aeyJaS OM} “TG {syUaTISIS 91De10Y} 94} UO seJIS UaAaS “41g ‘sliv[JaUI4s Bjas ‘oje[d Ie[[aUI93s “q $g-I Winuss}s [PulUOpqe uo aejos Inoj ‘F “8 %@ ‘Ty SqudtSas [eUIWOpe Y}6 UO Os[e pu ‘WINUID}S O1OBLOYYeJOU Pue -OSAUI UO av}aS aTsuIS OM} “MD fuUNUIA}s d1oR10y}OId uO eyaS I[ZuUISs ‘TH fsITeUsa}s PyaS ‘a}e[d [eUI|}s “M {syUSUIdIS [PUIWIOpge Ud} 9Y} ‘OI-I ‘fs}zUatUSaS D1OeIOY} 9214} 94} ‘III ‘II ‘IT :peey ‘29H ‘OF “OI. dO NOILVNVIdXq] ‘podse [e1oye] ‘9D ‘[esiop ‘gq ‘Teayuaa “VW favyas JO JUaWaSueIIe pue ainjonss Surmoys ‘easel UMOIS-AYNY : YOU Snrpisayoue SnyIi4zoYyJDUH— GE “OT 70 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 The structure and general appearance of the larva are shown in figure 36. The larva is legless, subcylindrical, white in color except the heavily chitinized and therefore reddish-brown headcapsula. The full grown larva is about 3.7 mm. long. Three thoracic and nine abdominal segments are well developed. The anal lobes may be re- garded as a tenth abdominal segment. The three thoracic segments are nearly equal in size and only little larger than the first abdominal segment. The abdominal segments decrease slightly in width and length toward the apex. All segments and the head are armed with constant setae. The statement of Hopkins (38) that “ with the ex- ception of scattering hairs on the head and on the scutellar lobes of the thoracic and abdominal segments the body is without distinguish- ing vestiture ” in Dendroctonus has been found to be not true. There occur at least in Dendroctonus valens distinct setae. That this is not exceptional in the Scolytidae has been proved by Russo (57) and the author. The latter has studied many species and has found that every examined species shows distinct setae. The following discussion is based on the full grown larvae only. The fact that the present study was made in a private home did not allow of rearing work and there- fore the question of molds, etc., cannot be discussed at present. THE CHITINOUS: SKEEETON THE HEAD The head of the larva is more simple in structural details than that of the adult. It is distinctly narrower than the first thoracic seg- ment when seen from above, but nearly equal in length and in width to the latter when viewed from the side. The general structure is shown in figure 36, the anatomical details in figure 37. The more striking differences in the larval head are found in the presence of a clearly defined front, clypeus, labrum, and a well developed sub- mentum. Epicranial suture -——The sutura metopica as well as the sutura fronto-verticale are well developed and double lined (a, b). They are not raised or padded as in the adults. Front.—The front (fig. 37, Fr) is triangular in outline, plano-con- vex and clearly defined by the epicranial suture. The lateral sides are bordered with six strong bristles each (d). These setae are here called setae fronto-lateralis. The base of the front is smooth without any armation. In the discussion of the larval setae it seems to be very useful to compare the results obtained with those of other authors. From the NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL FL literature available, only two species have been found to be studied at the present. These are Dendroctonus valens Lec., investigated by Hopkins, and Chaetoptelius vestitus Fuchs studied by Russo. The ea Pst Fic. 37.—Gnathotrichus materiarius Fitch: Head of fully-grown larva; A, fron- tal aspect, B, ventral aspect, C, lateral aspect, D, occipital aspect. An, antenna; C/, clypeus, seta clypei; Eg, entogular plate; Ep, epicranium; Eph, epi- pharynx; Est, epistoma; Fr, front; Ge, gena; Gu, gula; Hst, hypostoma; Lar, labrum, setae labralis; Li, ligula; Md, mandible; Me, mentum; Mz, maxilla; Occ, occiput; Ocd, occipital apodeme; Pr, pregena; Pst, pleurostoma; SM, submentum; Ve, vertex; a, sutura metopica; b, sutura fronto verticale; c, seta geno mediana; d, seta fronto lateralis; e, seta epistomalis; f, seta verto mediana; g, seta verto lateralis; h, seta geno lateralis; 7, seta epicrano-lateralis; 7, gular suture; k, maxillare foramen; stl, sternal lobe. comparison of the setal arrangement with the latter species will be given at the end of each chapter. Clypeus—As mentioned before, the clypeus (fig. 37, Cl) is well developed in the larvae. It consists of a nearly rectangular plate which is heavily chitinized, distinctly emarginate anteriorly and broadly rounded antero-laterally. Basally it is separated from the 72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL, 82 epistoma by a faint suture. A pair of bristles and two punctures occur near the basal margin. The setae are called setae clypei. Labrum.—The labrum (fig. 37, Lar) is basally separated from the clypeus by a distinct suture. It consists of a heavily chitinized half circular plate. It is as long as, and about one-third narrower, than the clypeus and bears several papilla apically. Half way of its length occur two long bristles, the setae labralis. E pistoma.—Between the front and the clypeus, a narrow thickened transverse band occurs which may be designated as the epistoma (Est). Laterally this structure is slightly bent forward and this part bears the dorsal articulation of the mandibles. On the latero- basal angles, near the suture, a long bristle is situated. The proposed name is seta epistomalis. Pleurostoma.—A faint suture hems the lateral portion of the oral foramen, parallel to the lateral exposed part of the mandibles, which cuts off a narrow area of the cranium. This area, the pleurostoma, is slightly raised externally; internally it is ridgelike, and connects the epistoma with the hypostoma. Hypostoma.—The hypostoma (fig. 37, Hst), which bears the ven- tral articulation of the mandibles, is rather ill-defined externally. In- ternally it is ridgelike and the articulatory condyles and fossa are submerged. Towards the occipital foramen it is extended in another ridge from which the connecting membranes of the maxilla and the submentum arise. Occipital foramen.—The occipital foramen (fig. 6, Oct) is situated on the caudad face of the head capsula. It is heart-shaped and is bor- dered by a ridgelike rim, the occipital apodeme (fig. 37, OcA). The latter is interrupted ventrally. The entogular plate extends into the foramen under the occipital apodeme giving the open space of the foramen the shape of a triangle, the sides of which are broadly rounded. Gula.—The gula (Gu) is present as two small lobes, each situated along the ventro-lateral angles of the occipital apodeme. The lateral limitation is indicated by an obscure suture. Entogular plate—A subchitinous plate (Eg) connects the genal areas and extends ventrally up to the hypostoma. It was called the entogular plate by Hopkins. The open space of the oral foramen is also reduced by the lammella-like extension of this plate. The entogu- lar plate is not visible externally but hidden from the submentum. Pregena.—A narrow area along the ventral extensions of the hypo- stoma, and laterally limited by obscure lines, may be considered as the pregena (Pr). NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 73 Other topographical regions of the cranium are not defined by sutures but they are somewhat limited by the occurring setae. V ertex —The area on both sides of the sutura fronto-verticale, the vertex (Ve), bears two groups of setae. Eleven bristles ({) are situ- ated along each side of the sutura fronto-verticale. Four of them are arranged in a single row along the suture; the rest occur in the angle formed by the sutura fronto-verticale and the sutura metopica. They are called setae verto-mediana. A single bristle widely separated from the setae verto-mediana, the seta verto-lateralis (g) presents the second group. Sometimes a minute hair is also visible near the latter mentioned bristle. Gena.—The area between the sutura metopica and the occipital apodeme ventro-laterally to the vertex is here designated as the gena (Ge). It bears two groups of setae, one on the level of, and close to, the antennae (c) and one laterally (h) to them but widely sepa- rated from them. The former consists of five, the latter of six long bristles. The corresponding names are the setae geno-mediana and the setae geno-lateralis. Epicranium.—tThe area dorsally to the genae and laterally to the vertex is called the epicranium. A single bristle (i) sometimes asso- ciated with a minute hair, is situated near the occipital apodeme. It is called the seta epicrano-lateralis. THE APPENDAGES OF THE HEAD THE ANTENNAE The antennae (fig. 37, An) are present as small membranous lobes next to the ventral end of the sutura metopica. Each bears one papilla and numerous minute hairs. THE MOUTHPARTS Mandibles —The mandibles (fig. 28) differ somewhat from those of the adults, in contrast to which only one median tooth is present and the shape of the mandible is more slender and triangular. The setae are present in the same number as in the adults but their position in relation to each other is different. Proposed names: setae mandi- bulae dorsalis and setae mandibulae lateralis. Mavzillae-—The maxilla of the larva (fig. 38, A) is much simpler in structure than that of the adult. However, all parts present in the adult maxilla are also distinguishable in the larva. The cardo (Ca) is present as a distinct sclerite, triangular in out- line and connected with the extended hypostomal ridge, the mentum and the stipes respectively. This is, as in the adult, not the only con- 74 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82 nection of the maxillae with the mentum. The subgaleal area is also connected with the mentum along its interno-lateral margin. The stipites (St) are distally not subdivided into a palpifer, and are fused internolaterally with the subgalea. A single bristle (b) occurs near the externo-lateral margin. It was called the setole laterale dello stipite by Russo. In the present paper the name is modified into seta stipitis maxillaris. The palpiferal area Fic. 38.—Gnathotrichus materiarius Fitch: A, labium and maxilla, ventral as- pect: B, clypeus and labrum, ventral aspect. Ca, cardo; Fr, front; Eph, epipharynx; Ga, galea; La, lacinia; Lab, labium; Lar, labrum; Lpp, labial palpi; Li, ligula; M, mentum; Ma, maxilla; Oes, oesophagus; Pp, maxillar palpi; Ppf, maxillar palpifer; SM, submentum; St, stipes; C, clypeus; a, seta palpifera maxillaris; b, seta stipitae maxillaris; c, seta ligulae distalis; d, seta submento-lateralis; e, papilla labro- apicalis; #, papilla epipharno-distale; g, papilla clypei; h, seta menti; 7, seta ligulae mediana; 7, seta labio-palpiferis, and palpiferal area; k, seta ligulae basalis, and basal area; /, seta lacinio-maxillaris; m, epistomal apodeme; n, apodeme between lateral angle of epistoma and dorsal angle of pleurostoma. bears two bristles (a) and one puncture; the outer corresponds to the setola laterale dello palpifera, and the inner to setola mediana dello palpifera (Russo), here called seta palpiferae (maxillaris). The palpus is two-segmented, telescopic, the first segment armed with a short fine hair and two punctures, the second with punctures only. The bristle on the first segment is the setola palpiale (Russo) but to dis- tinguish it from possible setae on other joints, it should be called seta palpo-maxillaris 1°. The lacinia is present as a well developed lobe distally armed with two long bristles (setae lacinio-maxillaris ) NO. 10 MORPHOLOGY OF GNATHOTRICHUS—SCHEDL 75 and a few papillae. The galea is largely fused with the lacinia. Dis- tally a rather shallow fold indicates the separation of these two sclerites. The setae of the maxillae have not been studied thoroughly enough to decide if they are of taxonomic importance or not. In Den- doctonus valons, no setae or punctures occur on the palpus and none of them on the lacinia, according to the drawings published by Hop- kins. On the other hand it was found that the setal arrangement of TABLE I.—Setae of the head, nomenclature. Nomenclature of Dr. Russo Used on New nomenclature Used on Setole mediane-distale ..... Setole submediane ....... BronGh acess saee Seta fronto-lateralis ........ Frons. SGUGIS TENGTEAIN Ceo toge conan : ; Ratner basalinescadcas cee o cents Frons-epistoma .Seta epistomalis ....... .--. Epistoma. Setole basali clypeali....... Glypeus! =. tsicee Setar clypeit casvsrcieisiecieiare ...-Clypeus. Setole mediane distali..... Setole premediane ........ ILeiayebir Go oadac Seta wlabraliisaeeveysettelatetete t=! Labrum. Setole sublaterali ......... Setole basali-laterali ...... A Seta verto-mediana ...-..-) vortex Seta verto-lateralis ....... ) Setole laterale del vertice.. Setole mediane ........... Genae ye ciieer -Seta geno-lateralis ....... .. Genae. Setole basale?.. ja: <2.» S908 eee He a del vertice.. Setole della gena.......... Setole mediane ... oat WGENAG | sertarsrers Seta geno-mediana ......... Genae. Setole esterna Setole basale Y Seta epicrano-lateralis ...... Epicranium. Setole dorsali ...1.+-12+++++Mandible ..1.Seta mandibuiae lateralis. . { Mandible. Rereialaterale dello stipite. . . 5tiPes aoc Oso Seta stipitae maxillaris...... Stipes. Setole mediane del palpifero. | Palpifer .......Seta palpiferae maxillaris....Palpifer. Setole laterale del palpifero. ' First joint of | Seta palpo-maxillaris 1°..... First joint of eLole palpiale) occ. cleccie «0 palpus. te ; . palpus. Seta lacinio-maxillaris ..... Laciniae. aa eee Ug ae Ges ae [Sabena ...Seta submento-lateralis ..... Submentum. 1 ; : Setole subbasali ......... ; Seta menti .....-...-.--.0. Mentum. Retalemenbhasalie.scsocce. _Mentum Seaeicrie etal lablo palpitenisircijeretelelere Beer ee : Seta ligulae distalis. Setole distale ............ Wei puila, smcen Seta ligulae mediana. Setole mediane ..:.....0ce if Seta ligulae basalis. Gn. materiarius Fitch is exactly the same as that of Chactoptelius vestitus Fuchs, illustrated and described by Russo. Labium.—tThe labium (Lab) of the larva is very different in struc- ture from that of the adult. Indications are that the labium of the larva as well as that of the adult will become more and more im- portant as the bearer of taxonomic characters in the Scolytidae. The submentum (SM) is present as a large sclerite and is trapezoid in outline. The shape is more like that of Chaetoptelius vestitus Fuchs. It is slightly chitinized, laterally connected with the maxillae and bears three pairs of setae (d), the same number and in a similar ar- rangement as in Chaetoptelius vestitus and Dendroctonus valens. Russo called these setae setole subbasale, setole mediane and setole distale in order proceeding distad. The anterior margin of the sub- 6 76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 mentum does not extend as far as the origin of the palpi as in the two other species mentioned above. The mentum (M) is a submembranous triangular plate the base of which is anterior. The posterior angle is narrow and strongly produced. Anteriorly it is fused with the palpiferal area of the labium. A single bristle and a puncture (h) are situated on the antero-lateral angles. The name proposed is seta ment. Tas_e I].—Comparison of head setal arrangement. Chaetoptelius Dendroctonus Gnathotrichus Seta vestitus valens materiarius Fuchs. Lec. Fitch. HM TOntoslatetallismme sera 4 4 6 Epistomaliswer rn... acs aerate I I I Gly peices cc gecesmnew oc Oca: 2 I I JEallp palliS Rese erctcrmtarsrs snscore Teel ones 5 2° I Werto-medianay qaceie secs sor (@) iF 12 Nertolatenalisne esta sce eer (a) ? 2 Geno lateralismeeee eee meio 8 pit 6 Geno=medianaue eee ene einen 4 @ 5 E\picrano-lateraliss apes (0) ? I Mandibulae-dorsalis .......... 2 2 2 Mandibulae-lateralis .......... I I I Stipitissimeaxallaris/eerserei cern I iP I Palpiterae maxallarisy sos... 2 R 2 Palpo-meaxalllanicneeenneeeeere I (a) I acinio-meaxallanismeer reece I (0) 3 Submento-lateralis..-5..--- 3 3 3 Mientti Sas tinesind fs icisraie saa atest 0) 0 I Lalor “sococnconocduec I I 2 Wigtlae=distalismecemeee ret I I I ioulae-medianaw eee rier (a) 0) I ieulaesbasalicuem mermtaeie I I I The ligula (Li) consists of a circular plate largely surrounded by the mentum. From subdivisional parts the base of the ligula is visible from which it is well defined by faint sutures and the palpi (Pp). The base bears a single pair of setae. They are present as two short bristles and are called the setae ligulae basalis. The palpiferal area is situated on both sides of the base. The part anterior to the base of the ligula and between the palpi may be designated as the distad end of the ligula. The palpi are two-jointed. The palpiferal area bears two setae (j) which are called setae labio-palpiferis. The distal area of the ligula is armed with two pairs of setae. Proposed names: setae ligulae mediana and distalis. NO. IO MORPHOLOGY OF GNATHOTRICHUS—SCHEDL WG) THE THORAX The thoracic segments are somewhat larger in size than those of the abdomen. They do not differ from each other in shape but are dis- tinguished by the structure and the development of the setae. The thoracic segments are legless as in the whole superfamily but the foot calli are distinct. Dorsally, the prothorax is distinguished from the other two thoracic segments by the lack of the suture which divides the prescutum (fig. 36) from the fused scutal-scutellar area. However, the prescu- tum is indicated by the corresponding setae. On the meso- and meta- thorax, the prescutum is present as a narrow transverse sclerite (f), near the anterior margin of which the prescutal setae (f,4) are situated. The scutum (e) and the scutellum are in all three segments fused. The pleural area is fairly well defined by a longitudinal fold ventrally. Latero-dorsally it is fused with the scutal-scutellar area. Another longitudinal fold divides the pleural area into two distinct parts. The part next to the scutal-scutellar area represents evidently the epipleurite (d), the ventral part the hypopleurite (c). The former has a smooth surface bearing setae only; the latter has the surface covered with minute spines beside the setae. On the sternum two subdivisions are plainly visible, the sternal (a) and the sternellar area (b). The sternellar area or sternellum consists of two large lateral lobes which are connected by a very narrow band medially. The lateral lobes which bear the foot calli are covered with minute spines similar to those in the hypopleurites. There is not enough evi- dence to speak about a poststernellar area in Gnathotrichus as it should be present in Dendroctonus according to Hopkins. The setal arrangement will be discussed with that of the abdomen. THE ABDOMEN The abdomen (fig. 36) consists of ten segments, the tenth of which is strongly reduced and present as the anal lobes. The segments de- crease in size slightly towards the apex. Segments one to seven in- clusively are alike in structure and setal arrangement. They differ in structure from the meso- and metathorax in having longitudinal folds which separate the epipleural area from the sternum and the scutal-scutellar area. Also the sternal-sternellar suture is restricted to a membranous fold. The two lateral lobes of the sternellum are apparently not connected medially. The eighth segment does not show signs of the prescutal-scutal suture. Still more reduced is the ninth segment ; it has no sutures or folds but the different sclerites can be 78 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 determined very plainly from the position of the setae. The anal or tenth segment is separated from the ninth by an obscure suture. It consists chiefly of the four anal lobes. There is no difference in the structure of these lobes and also armations do not occur as in other genera. THE SPIRACLES Nine pairs of spiracles are present, eight of which are situated on the epipleurites of the first eight abdominal segments. The ninth spiracle is on the same sclerite of the prothorax very close to the mesothorax. THE THORACIC AND ABDOMINAL SETAE It was found that the setal arrangement is very constant from specimen to specimen. The number of setae varies in the different seg- ments. The smallest number of setae was found to be present in the anal segment (2 x 2) and the eighth abdominal segment (2 x IT) ; the greatest number was borne by the meso- and metathorax (2 x 22). The number of setae in the different segments is best explained by Tasie III].—Setae of thorax and abdomen, nomenclature. Used on the Used on the Nomenclature of Dr. Russo segments New nomenclature segments Fig. 36 Setole tergali mediana.......... Ti, UES JU re : F Tae t Sefoleuprotercalistemeiteerorsieterts 1-8 {Seta praescutl ...++- 1-9 t Setole posttergali .............. I, IT, III, 1-8 Li. Wa Setole tergali-laterali .......... I Setay scutilul cyvsieiete iiet) ? Setole tergali ee ienicoee ont 9 Setolemepiplerri cremrecteratcieielerslerer I, 1-8 I Wut Setole pleuri-sternali .........-. 1 Seta epipleuricum ... } EM ot) , t d Setole fereal pleural: dsisistinieret 1 a 1-9 Setole upopleuralt, (eee res) nn sle'es ar Setole pleurali-sternali ......... z set hypopleuricum .. { I, 1, WII, ¢ c Setoleepipleunit ie ocr isereleleiaieletee 15 ANE 38) Setole sternali-anteriori-externe. . I Setole sternali-posteriori-externe.. I Setole sternali-mediane ........ I Oncor Setoleipopleurales -r-teretejers cle cievele Mis Seta sternellaris 2 hee Ai b Setole sternali-laterali .......... its LAU 1-9 Setole sternali mediane......... his 1H Setole stermaliy i