FIFTH REPORT OF THE DIRECTOR I908 



195 



son and Ethericlge from the Lower Siluric of Ayrshire, England, 

 placing it with some doubt among the Codiaceae to which he also 

 referred the Mesozoic Sphaerocodium. Both Girvanella and 

 Sphaerocodium form compact bodies essentially composed of an in- 

 tricate mass of fine continuous tubes. Alexander Brown next took 

 up the problem of the taxonomic position of Solenopora, 1 a genus 

 that in Solenopora com pacta (Billings) , its genotype, is 

 well represented in the Lower Siluric of Xew York, and discov- 

 ered its cellular structure (a tubular one was assumed before), 

 finding that its cells bear great similarity to those of certain living 

 and fossil coralline algae and that there are also traces of tetra- 

 sporangia and conceptacles corresponding to those of the recent 

 Corallineae, to which he therefore refers Solenopora as a possible 

 ancestor of the recent nullipores. 2 



E. Stolley 3 in 1893 demonstrated the presence of indubitable 

 calcareous algae in boulders of northern Germany derived from 

 the Lower Siluric of Sweden and described a number of forms 

 which exhibit relationship to the recent Borneteila and the triassic 

 Gyroporella, and all of which were undoubtedly verticillate Si- 

 phoneae except one (Arthroporella eaten ularia) which 

 consists of chains of spheric and pear-shaped bodies and is com- 

 pared with the Eocene Ovulites. 



Finally. Whitfield 4 placed a form hitherto referred to the grapto- 

 lites (B y t h o g r a p t u s lax us) among the algae, principally 

 for the reason that the secondary branches are connected by distinct 

 articulations with the central stipe and that proper cell apertures 

 are absent or indistinguishable. 



1 Brown, Alexander. On the Structure and Affinities of the Genus 

 Solenopora. Geol. Mag. TV. 1894. p. 145. 



2 Professor Rothpletz has lately published the results of his most thorough 

 and painstaking investigations of these difficult and problematic forms [see 

 Ueber Algen und Hydrozoen im Silur von Gotland und Oesel, in Kongl. 

 Svenska Vetensk. Handl. Bd. 43, no. 5, 1908] positively placing Gir- 

 vanella problematica. and Sphaerocodium,- to which also a Siluric 

 form is referred, as well as Solenopora, among the algae. As most important 

 for the taxonomic position of Solenopora, he considers the presence of 

 perforations of the cell walls discovered by him, the arrangement of the con- 

 centric rows of cells and the similarity of the tubular, isolated sporangia in 

 Solenopora go 1 1 a n die a and the Archaeolithothamnia. 



In a review by Steinmann (Zeitschr. fur Tnduktive Abstammungs-und 

 Vererbungslehre, Bd. 1, Hft. 4, p. 405, 1909) that has just come to hand the 

 existence of probable transitional forms (in the Permian limestones of Sicily 

 and the Jurassic) between the Siluric Solenopora and Lithothamnium, that 

 begins in the Cretaceous period, is pointed out. 



3 Ueber silurische Siphoncen. Neucs Jahrbuch 1893. 2:135. 



4 Whitfield, R. P. On New Forms of Marine Algae from the Trenton 

 Limestone, with Observations on B y t h o g rapt u s 1 a x 11 s Hail. Bui. 

 Am. Mus. Xat. Hist. 1894. v. 6, art. 16, p. 351. 



