March 27, 1879] 



NATURE 



485 



liave a striking general resemblance to those of the orbit 

 of Biela's comet, in the descending node of which body 

 the earth was precisely situated at the time. 



FOSSIL CALCAREOUS ALGJE 



THE very important memoir of M. Munier-Chalmas, 

 "Sur les Algues calcaires appartenant au groupe 

 des Dasycladees Harv. et confondues avec les Fora- 

 minif^res," which was published in the Comptes Rendus 

 Hcbdomadaires of the French Academy of Science for 

 October 29, 1877, opens up quite a new or almost a new 

 field of research, which has been followed up by the same 

 author in a note presented last month to the Geological 

 Society of France, " On the genus Ovulites." Though 

 regarded by some of the most eminent palaeontologists 

 as a monothalmic foraminifer related to Lagena, the genus 

 Ovulites is herein clearly demonstrated to be neither more 

 nor less than an articulation of a siphonaceous alga having 

 very close affinities to Penicellus. 



Ovulites margaritula is described by Messrs. Parker 

 and Jones " as a common Foraminifer of the ' Calcaire 

 grossier.' Shaped like an egg, and when full grown 

 about the size of a mustard-seed, it is one of the most 

 elegant of the fossil forms. The large terminal apertures, 

 moreover, curiously impress upon the mind its resem- 

 blance to a ' blown ' bird's egg. [Written in i860 ; nowadays 

 bird's eggs are not thus blown.] It is the largest of the 

 monothalamous Foraminifera. As a species it appears 

 to have been short-lived. Fully developed in the deposits 

 of Hauteville and Grignon it breaks in at once in the 

 Eocene period. It lingers as an attenuated form in the 

 Miocene beds of San Domingo. A recent Ovulite has 

 not been met with. Scarcely another Foraminifer pre- 

 sents us with a similarly brief historj- — an undescribed 

 form allied to Dactylopora affording almost the only 

 parallel (namely, Acicitlaria pavantina, d'Arch.)." 



In passing it may be noted that without doubt this last- 

 mentioned form is also only a portion of a calcareous alga. 



The earlier memoir, of which the Comptes Rendus pub- 

 lishes only an abstract, reminds us that it is not so very 

 long ago (1842) since Prof. Decaisne demonstrated that a 

 number of marine forms known as zoophytes, Corallina, 

 Cymopolia, Neomeri 5, Penicellus, Udotea, Halimeda, &c., 

 were in reality veritable algas. But we may remark that 

 Prof. Schweigger, of Konigsberg, had, from actual obser- 

 vation of living specimens of several species of these 

 calcareous algze at Villefranche, come to the same con- 

 clusion in 1818 (" Beobachtungen auf naturhistorischen 

 Reisen. Anat.-phy3. Untersuchungen iiber Corallen," 

 Berlin, 1818). To go back to the pre-Linnean times, 

 Ray (1690) described Corallina as " plantse genus 

 in aquis nascens," and Spallanzani, Carolini, and 

 Olivi even maintained the same against the peculiar 

 reasonings of Ellis, the authority of Linneus, and despite 

 the conversion of Pallas ; but so influenced by autho- 

 rity were, apparently, the botanists down to 1842, 

 that a Professor of Botany in the Edinburgh University 

 (Graham) once politely requested the zoologists to keep 

 their cr>-ptogamia to themselves, and a Professor of Botany 

 in the Dublin University (Harvey), in the first edition of 

 his "Manual of British Algae" (1841), did not include 

 any of the Corallines. Since the memoirs of Decaisne 

 and Chauvin, all this has changed, and we imagine that 

 there is now no difference of opinion existing among 

 botanists as to the general affinities of the living forms 

 of calcareous algae. 



M. Munier-Chalmas in his memoir demonstrates that 

 there must be also added to this group a numerous series 

 of fossil forms which the old authors placed among the 

 polyps, and which most of the modern writers on the 

 subject have ranked among the foraminifera. Bosc in 

 iSoiS described and figured (^Journal de Physique, Juin 

 iSo5) some fossil organised bodies under the name of 



Reteporitcs ovoides, for which bodies Lamarck in i8i6 

 established the genus Dactylopora. " The most singular 

 varieties of opinion have e.xisted," writes Dr. Carpenter 

 in his well-known " Introduction to the Study of the 

 Foraminifera," "as to the true character of these fossil 

 organisms. In separating them generally from Retepora 

 Lamarck still associated them in the same group of sup- 

 posed zoophytes ; this position was also accepted for the 

 genus by De Blainville and Defranc." [It is but justice 

 to De Blainville to point out that he quotes \vithout dis- 

 approval the statement of Schweigger, "que les dactyl- 

 pores et les ovulites ne sont rien autre chose que des 

 articulations d'une grande espece de cellaire, analogue a, 

 la cellaire salicorne"]. "In 1852 Dactylopora was in- 

 cluded among the Foraminifera by D'Orbigny, who 

 showed, notwithstanding, by the place he assigned to 

 it, a misapprehension of the real nature scarcely less 

 complete than that under which his predecessors had 

 lain ; for he ranks it in his order Monostfegues, ne.xt 

 to the unilocular 0\-ulite5, and says of it : ' C'est une 

 Ovulite dgalement percde des deux bouts, pourvTie des 

 larges pores places par lignes transverses.' How utterly 

 erroneous is this description will appear from the details 

 to be presently given, yet D'Orbigny's authority has given 

 it currency enough to cause it to be accepted by such 

 intelligent palaeontologists as Pictet and Bronn, who in 

 the latest editions of their respective treatises have trans- 

 ferred Dactylopora to the place indicated by him, not, 

 however, without the expression of a doubt on the part of 

 Bronn as to whether the true place of the genus is not 

 among the Fistididae in alliance with Synapta and Holo- 

 thuria — a suggestion that indicates a perversion of ideas 

 on the subject for which it is not easy to account. The 

 complex structure of the organi.sm in question was first 

 described and the interpretation of that structure on the 

 basis of an extended comparison with simpler forms was 

 first given, by Messrs. Parker and Jones in so unobtrusive 

 a manner as scarcely to challenge the attention which 

 their investigations deserve, and I gladly avail myself of 

 the opportunity which the present publication affords to 

 give a fuller account, with the requisite illustrations of 

 this remarkable type, the elucidation of which seems to 

 me not unlikely to lead to a reconsideration of the place 

 assigned to many other organisms at present ranked 

 among Zooph}-te5 or Polyzoa ; " and then follow nine 

 pages of a most elaborate description of every ridge and 

 furrow, of every elevation and depression to be met with 

 in any of the so-called species, so that probably no single 

 vegetable cell was ever before so minutely described. 



The genus is placed the eleventh in order of the family 

 Miliolida, a family which contains some of the most 

 typical of Foraminifers. " It may be conjectured with- 

 out much improbability," writes Dr. Carpenter, "that 

 Dactylopora is only the single representative of a group 

 whose various forms filled up the hiatus which at present 

 intervenes between itself and its nearest allies among the 

 ordinary Foraminifera." But, wTites M. Munier-Chahnas, 

 " the study and comparison of species of Dasycladus, 

 Cymopolia, Acetabularia, Xeomeris, &c., inthe herbarium 

 of the museum, and in that of M. Ed. Bornet, who 

 placed without reserve at my disposal his library' and 

 ! collections of these plants, proved to me that the species 

 ! of Dactylopora, Acicularia, Polytrypa, lic, are decidedly 

 I Algae, very nearly allied to species of the recent genera 

 just quoted, if not identical therewith. The accompany- 

 j ing figures show plainly, for example, that the genera 

 Cymopolia and Polytrj-pa may be united ; for the t\-pical 

 species thereof offer in every respect the same generic 

 characters, and there is even a difficulty to find for them 

 sufficiently distinct specific characters. Under the 

 denomination of *■ Siphonece verticillatce'' I unite (i) 

 Those green-spore bearing algae arranged by Harvey in 

 the family of the Dasycladeae ; (2) All those fossil gener 

 related to Lan-aria, Cl>-peina, Polytrypa, Acicidaria, Dae- 



