484 



NATURE 



{Sept. 



1 88 1 



nian Plants of Canada," and subsequent Reports on the plants 

 of the Lower Carboniferc us and Millstone Grit formations (Geo'. 

 Survey of Canada, 1871 and 1873). I" these circumstances it 

 seems strange that tte receiverl conclusions as to their age 

 shou!d be termed "simple negation not supported by facts, "and 

 regarded as rf no scientific value in comparison with the mere 

 assertion of a gentleman who has no knowledge v\halever of the 

 stratigraphy of the region, and with the "authority" of Dr. 

 Heer, wlio is no doubt an excellent authority on certain depart- 

 ments of European paleobotany, but «ho has irot seen the lieds 

 in question, nor, so far as I am aware, studied their fossils. 



The beds referred to, like the Devonian generally in Ea tern 

 Canada, underlie unconformably the lo\ve>t Carboniferous beds, a 

 <;ircum- tance due apparently to the extensive igneous action 

 which closed the Devonian period in this region, givirg origin to 

 masses and dykes of intrusive graniie, and disturbing and par- 

 tially altering the str.ita of Devonian and greater age, the 

 materials of which have contributed to the Lower Carboniferous 

 conglomerate^. There is tl us no question here as to any transi- 

 tion between Devonian and Carboniferous, and the beds holding 

 the plants and insects are stratigraphically pre-Carbofiiferous. 



The Lower Carboiiferous beds, succeeding to the Devonian 

 formati m, and developed to the eastward of St. John, hold the 

 characteristic flora of the Horton series, or Lowest Carboni- 

 ferous, equivalent to the Caliiferous or Tweedian formation of 

 Scotland. In succession to this we have the flora of the Mill- 

 stone grit, of the true Coal-Measures, and of the PermoCar- 

 boniferous or Lower Permian. All of these have been explored 

 and their plants catalogued and descrilied in my own memoirs 

 or in the reports of the Ceological Survey, and it has been fully 

 e-tabli-hed that the flora of the Devonian beds is characteristic 

 and distinct from any of these ;ub-floras of the Carboniferou-. 



T he plants of the Cordaite shales are not only distmguishable 

 from those of ihe Carboniferous found in their vicinity, but the 

 assemblage includes forms like Psitophyton and A'chivopteris, 

 which are j:haracteristic of the L'levonian, and are not found in 

 the Carlioniferoui elsewhere in America. In the Devonian of 

 Northern New Brunswick some of the-e plants are associated 

 with fishes of the genera Cfphalaspu, Pterichthys, &c., well- 

 known Devonian types. 



For additional information as to the geological relations of 

 the St. John plant beds and notices of new species, I may refer 

 to my paper on "New Erian Plants," in the yo?/rKfl/ of the 

 Geological Society of London, voL xxxvii.. May, 1S81. This 

 paper Dr. Hagen had probably not seen at the time when his 

 letter was written. 



The particular fern in question, Pccapteris serrulata of Hartt, 

 has been fully described, first by Prof. Harlt, and subsequently 

 by myself, and its distinctness from P. phimosa pointed cut.- 

 The criticism of Dr. Hagen, as to its not appearing in the 

 sectional lists, and still being called by me a common fern, is 

 based on a mere accident, which 1 could easily have explained 

 to him. The plants referred to as found in each layer in the 

 detailed section are tho-e originally described by me from these 

 beds. Some species, subsequently recognised and described by 

 Hartt, were not included in the sectional li'-ts, and were referred 

 to only in a note, because I had received no information from 

 Prof. Hartt as to the particular layers in which they were fi und, 

 though I knew that ;0'.ne of them were by no means uncommon, 

 from the number of specimen obtained. Dr. Hagen criticises 

 my figure of the species, but that does not affect the question, as 

 1 have compared the specimen on the slab with Plalephcinaa 

 with the original specimens in my collec'ion. My figures, how- 

 ever, show fairly the general form of the frond ; and there is 

 also a magnified figure of a pinnule, showing the venation, 

 which should enable any one to recognise the species, and with 

 the' aid of the description to distinguish it from P. plumosa. 



With regard to the " Ura stage" of my respected friend Dr. 

 Heer, founded on a little known and apparently exceptional 

 locality, 1 have alv\ays objected to its being made a standard of 

 compari; on for the thoroughly worked and widely distributed 

 Devonian or Erian rocks of North Ameiica. I gave some 

 reasons for this in a paper sent to the Geological Society of 

 London ihortly after the appearance of Dr. Heer's memoir, 

 an abstract of which appears in the Proceedings of the Society. 

 It will be sufficient to say here that the grounds on which Dr. 

 Heer refers the Devonian .if New Brunswick to the Ursa stage 

 would apply to the Chenning, and even to the Hamilton forma- 

 tions of the New York series. 



^ " Acadian Geology : "Report on Pevonian Plants." Canadian Natura- 

 Ihl, 1881. 



The great richness of the Devonian of North America in fossil 

 plants is a very remarkable geological fact, wh-ch I regret to say 

 has hitherto far exceeded the means available for its adequate 

 illustration. I hope, ho« ever, to remedy this to some extenton the 

 occa ion of the meeting of the American A s elation in Motreal in 

 1882, when my whole collection of Erian plants together with 

 tho-e illustrating the sevtral stages of the Carboniferous, will 

 be exhibited in the new Peter Redpath Museum, and will show 

 more fully than has been hitherto possible the progress of the 

 American flora from the Silurian to the Permian. It will be a 

 great pleaure to me if any patoobotanists who are sceptical as 

 to the magnitude of the Devonian flora will avail themselves of 

 this opportunity to judge for themselves and to form their own 

 opinions as to the affinities and relations of the specie^-. 



McGill College, Montreal, September 2 J. \V. Dawson 



Sound-producing Ants 



1 AM glad to see my rtatement in Nature, vol. xxii. p. 583, 

 verified by Mr. H. O. Forbes, from Sumatra, and now inclose 

 a few ants of another kind that make this peculiar tapping or 

 scratching sound, though not in the same system of taps as thofc 

 before noted, and that was thus — 



i.e. three taps in unison and a pau;e of about a second, the 

 taps of equal duration. The ants inclosed make a series 



• that dies off and dees rot seem repeated 



unless the exciting cause again acts, when they again start in 

 beautiful unison. How they so correctly start together in .nil 



case; of - - - • or the and keep each 



tap in time, is really wonderful. White ants make similar 

 tappings, tut not in rhythm as far as I know, and they use it !o 

 call or warn. These little black ants cannot be heard by us 

 unless the material they are on is sensitively soirorous. Happen- 

 ing to place a tumbler on a sideboard lately in the dark, I was 



startled to hear this . - - . arise from a su^ar-bowl. I 



repeated it, and the noise at once convinced me that it was ants. 

 On getting a light I found a sheet of writing paper had been laid 

 on the bowl, and was covered by them ; the glass aljne was use- 

 less, I found. S. E. Peal 



Asam, July 6 



[The ants sent are apparently "wcrkers" of a species not 

 larger than a small British JMyymica. — Ed.] 



Wasps 



A COUPLE of weeks ago I found on my window-pane a large 

 black wasp hoi: ing in its mandiWes a plump spider of about 

 an eighth Of an inch in diameter. I placed the wasp uirder a 

 bell-glass and set it on my desk, where I could readily watch for 

 further developments. Finding itself in captivity, the wasp 

 dropped its booty and spent some time in trying to find a way of 

 escape. Coming at length to a state of rest, it espied the spider 

 and sprang upon it with tiger-like fierceness. Seizing it and 

 raising itself up to its full height, the wa<p brought its po terior 

 under and forward with a quickj motion, and gave the spider, 

 two or three thrusts with its sting. Assured that the spider was 

 dead, the wasp proceeded to roll it over and over-, I'apidly work- 

 ing it up into a globular n,as. This done it started to fly away ; 

 but, foiled in the attempt, it dropped the spider, which was for 

 some time apparently forgotten. This whole operation I sa« 

 several times repeated durirg the two days of my observations;. 

 Being called away from home for a few days, I was curious on 

 my return to ascertain the results of my experiment. I had 

 taken the precaution at the fii-st to place under the bell-glass a 

 small dish of clean water, to which the wasp had helped itself 

 freely. I found the wasp dead ; but not the least morsel of the 

 spider had it eaten. My conclusions are : (1) that the wasp died 

 o( starvation ; (2) that the spider was intended, not for its own 

 food, but for that of its young in their larval state. In confir- 

 mation of this I have broken open several of the finished cells 

 of these wasps, and found them filled with pellets made of 

 portions of spiders, flies, and worms. Only yesterday a fine 

 opportunity was afforded me for further obseVvations in this 

 direction. One of my flowering vines is infested with a green 

 worm— the larva of the yellow butterfly. I di^-covered a bronre- 

 and-yellow wasp standing on the edge of a leaf of this vine, 

 holding fast to one of these worms of twice its own size. The 

 worm was dangling in mid-air, and the wasp endeavoured labo- 

 riously for a long time to pull it up on the surface of the leaf. 



