ii6 



NATURE 



[May 30, 1895 



was corrected by Prof. Briber in 1875 = """ "i'-' various brilliant 

 [lapers on the I'rimoniial formations by this author have given 

 the (:V<-«<r///«-fauna a marked and peculiar interest. In "1882 

 Linnarsson next made known the existence of the OUnciliis- 

 fauna in -Scania, at the base of the Swedish Cambrian. In 18S6 

 the same fauna was detected by Mickwitz in the Lower Cambrian 

 of Russia (Ksthonial, and this Rus.'^i.an fauna was figured and de- 

 scribed in detail by Dr. K. Schmidt, of St. Petersburg. In iSS? 

 Dr. Holm reported the existence of the C'/<H<//Hj-fauna in the 

 Cambrian of Lapland, where it w.-is tirsi detected by -Miirstell in 

 1885. Thus the existence of this remarkable fossil group, the 

 ohlest well-marked fauna recognised by geologists in the Lower 

 Cambrian, had already been demonstrateil. in 1 888, in three main 

 regions, namely : (i) in the region of the Kocky Mountains : (2) 

 in the region of Xorth-easlcrn -Xmtrica ; (3 ( in the region drained 

 by the Baltic Sea. L'p to 1SS8 no recorded account of the dis- 

 covery of Olciiellus from the British Isles had been published, the 

 oldest fauna descritied being the overlying raradoxides-zone.% or 

 .Middle Cambrian formation. 



"The first recognisable traces of OUnellus\x\ Britain were dis- 

 covered by Prof. I^pworth in 1885. Further collections were 

 made in 1887 and 1888, on the flanks of Caer Caradoc, Shrop- 

 shire, and the s|)ecies was named, in honour of Dr. Charles 

 Callaway, OUncllus Callavci. I^ter on it was figtired and 

 described in the Gfologiial Magazine for 1 891. 



"In -\ugust 1S91, Sir .■\. lieikie announced, at the British 

 A«ociation meeting in Carditf, the discovery of Okiicl/iis by 

 Messrs. Teach and Home, in blue-black shales, a few feet below 

 the " Serpulile Crit " of the Cambrian rtKks of North-west Scot- 

 land, in the Dundonnell Korest of Ross-shire. The description 

 of " the 0/ciiet/iis-zone of the North-west Highlands "" formed the 

 subject of a most valuable pajx-r by Messrs. I'each and Home, 

 read before the lieological Society on February 10, 1S92, and a 

 new species of OUiiclliis is descrilwd ami named ('. I^ifMorthihy 

 these authors. Mr. B. N. I'each, F. U.S., communicated a 

 .second pa[K'r, " -\dditions to the Fauna of the Oleiiel/iis-Tone of 

 the North-west Highlands,"' on June 20, 1894 ; in which, in ad- 

 <lition to O. /.afr,vorlhi, he describes and figures O. I.af^orthi 

 var. ehngaltis, O. rclicu/atiis, O. gigas, O. intermedins, and 

 OUneiioidrs arntatus. 



" ' The Fatma of the I^iwer Cambrian or Olenellus-i.ona ' forms 

 the subject and title of an admirable monograph by .Mr. C. D. 

 VValcott, F'.G.S., which, with the exception of the subsequent 

 discovery of an Olencllns-ixunn. in the Lower Cambrian of the 

 .Scotch Highlands (already referred to), gives us a very complete 

 and up-to-date account of this interesting and oklest fauna. 

 -About eighteen widely distributed localities are shown on the map 

 of North .\merica from British Columbia to I^-ibrador, and .as far 

 s*">uth as Texas; whilst in F-urojxf we have Spain, North and 

 .South Wales, the .Scottish Highlands, Norw.iy, -Sweden, Finland, 

 Bohemia, Bavaria, I'odolia, -Sardinia, I'ctchoraland,and the Ural 

 Mountains. (Jmiiting trails, burrows, and tracks, the Olenclliis- 

 fauna ha> yielded fifty-five genera of iirganisms, fifteen of which 

 arc Triloliitcs. 



" \Vc may now add yet another locality in which this remark- 

 able fauna occurs, .as proved by the presence of the remains of 

 OUnellus and the pteropKl Saltcrella : namely, in Western 

 Australia, where it w,as discovered by .Mr. Hardman in 1 886. 



" I must here refer to the iliscoveries of the limbs of trilo- 

 Irites. In 1870 the late F. Billings, the I'al.eontologist of the 

 'icologica! .Survey of Can.-iila, brought iKrdire the Geological 

 Society and descrilK.-d a siiecimen of .Isap/iiis flaly^ef'hahis, 

 from the Trenton Limestone of Ottawa, Canada, exhibiting 

 remains of eight pairs of limbs, corres|Kinding with the eight 

 free an«l m'>vable segments of the Uxly, and showing the hy|Ki- 

 s^ime still attached to the doublure of the anterior Imrder of ihc 

 cephalic shield ; traces of two appcniLagcs under the caudal 

 shield were also visible. <*n that i>cc.ision I exhibited a speci- 

 men of Asaphui from the same l<tc;diiy an<I horizon, showing 

 evidence of a small 7-8-j'iinte(l jialpus lying at the side of the 

 hyj»»iomc apparently in its original jHisition. After some re- 

 marks on the su|>erficial character of trilobites, I adiled : — 

 ' The prominence of the hypostome in the trilobiia reminds one 

 even more strongly of the genus Apia than of the iso|KKls, and 

 "ible toexpect in thetrilobita a moregeneraliseil 

 ihan that which m.irks the moilern reprcscnta- 



" In iW»i, after many years of untiring labour, Charles 

 D. Walcott furnished most conclusive proofs of the exist- 

 ence of appendage!) t-) the cephalic, thoracic, and alxlominal 



NO. 1335. VOL. 52] 



divisions of Caiynune. iSeraunis, and .tcidaspis. His researches 

 have twen carrie<l on by the method of making thin transverse 

 and longitudinal sections of rolled-up. specimens. He has shown 

 that the ventral body-wall of the trilobites was bounded inftriorly 

 by a thin chitinous membrane, which was attached to the lower 

 maiijin of the dorsal exoskeleton all round. This ventral mem- 

 brane was supixirted by calcified arches, which gave attachment 

 to the ap)Tendages lieneath. He further est.iblishcd theexistence 

 of a row of articulated cylindrical limbs, on each side of the 

 middle line. Walcott descrilied the thoracic api)endagcs in 

 Ca/ymene as slender six-jointed walking-legs (endo|H)ditesl with 

 a single pointed termination, the ba.sal segment giving rise to a 

 branch apjx-ndage (exopodile). t)n e.ich side of the throracic 

 j cavity he also described a row of bifid spiral appendages, of the 

 nature of gills, and he suggested that branchia were attached to 

 the Iwses of the thoracic limbs as well. The abdominal or 

 pygidial rings carried appendages, a [xtir to each segment, bat 

 they do not appear to have diflered from the thoracic limbs, save 

 in size. The mouth is situ.ated behind the hypostome, and has 

 four ]iairs of jointed manducatory organs, the bases of which 

 are modified to serve as jaws ; the hindmost pair being the 

 largest, and exjianded at the distal extremity into a swimming- 

 oi^an. 



" The correctness of Billings's views, as to the nature of the 

 thoracic limljs of Asap/iiis platyeephahis, was further confirniBil 

 by the finding of a s]x"cinien of Asaphns i>iegis/os, in the Ordo- 

 vician rocks of Ohio, which shows the under surface with its 

 apix'ndages, described by Llr. I. Mickletmrough. Thisspecimer* 

 shows two (lairs of maxillipeds or jaw-feel, eight |)airs of walk- 

 ing-ap|iendages, corresponding to the eight (lairs of free thoracic 

 segments, each limb having about six joints. The under side 

 of the coalesced segments of the abdomen (pygidiuni) reveals a 

 series of from twelve to sixteen similar paired appendages, 

 diminishing rapidly in size from before lackwanls to tlu 

 extremity. .'\ bro,id median groove extends along the undtr 

 side of the thorax and abdomen, and probably represents the 

 .space once occupied by the stemites or, possibly, the straight 

 intestinal canal, observed l)y Barrande in some trilobites from 

 Bohemia. Traces of su]iposed branchial filaments have also 

 been observed in this specimen, apixirently att.ached to the 

 thoracic legs. 



" No further addition had been made to our knowledge of the 

 appendages of triobites until July 1893, when Mr. \V. D. 

 Miitthew, a student of Columbia College (N.V.), comnninicated 

 the result of his examination of several specimens of Triiirfhnta 

 fiitiii, obtaine<l by Mr. W. .S. \'aliant from the ' Hudson River 

 Shales' (Ordovician), near Rome, New York. After recording 

 the extent of our previous knowledge derived from the im- 

 portant researches of C. D. Walcott, he proceeds to descrilie the 

 additions which the sjiecimens from Rome have supplied. These 

 trilobites are found in a soft, fine, black shale, and are perfectly 

 well preserveil. The most noticeable character is the presence 

 of long, sleniler, many-jointed whip-like appendages attached to 

 the front of the hea(l, closely reseml)ling the flagellate antenna- 

 of other crustaceans. These originate beneath the antcrioi 

 border of the head-shield, and are .as long .tgain nearly as the 

 glabella itself. .Mr. Matthew also w.ts atile to detect a series 

 of walking or swimming-legs, one a narrow, jointe<l, cylindrical 

 leg, the other thin, broad, fringed with a comb-like structure 

 similar to the gills of many Crustacea. 



" The next communicatiim is from Mr. C. K. Beccher, of New 

 Haven, Conn., ' On the .Mode of Occurrence ami Ihe Structure 

 and Development of rriarlhrus Keekii." The material gathered 

 fi)r the Yale University (by the aid of I'rof. -Marsh), near Koine, 

 New York, is probably some of the best which has been ob- 

 tained, and has been carefully examined and described by .Mr. 

 Bccchcr. 



" In their present condition the specimens from Rome contain 

 very little calcite, nearly the entire calcareous and chilinous 

 |K)rtions of Ihe trilobites being replaced by a thin film of iron 

 pyrile. To this cause is doubtless due Ihe preservali(m of deli- 

 cate f)rgans and structures which wimld otherwise have been 

 destroyed. 



" The siiccimcnslhus preserved occupy an extremely reslriclcil 

 vertical distribution, but within this range they are nearly all 

 complete, and ]»reserve their ap])endages. They are of allagcN, 

 from larval forms u]i to full-grown individuals, whilst the ail- 

 jacent strata cimtain a rather sparse fauna in which the trilobites 

 are generally Iragmentary and without appendages. The author 

 believes that, in Ihe majority of beds in which Irilobiles are 



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