PROCEEDINGS OF SECTION C. 383 



more elongated cells, at first fusiform and obliquely partitioned, finally 

 passing into a simple tube of the appearance of a typical Girvanella, 

 but not produced to so great a length as in the finer-tubed species. In 

 one instance at least, the earliest cell is seen lying within the axial 

 canal of a crinoid arm-ossicle, and bears numerous papilliform out- 

 growths near its free extremity (see pi. L, figs. 5, 6.) 



The larger tubed forms of Girvanella are strongly suggestive of a 

 relationship with the siphoneous algae, and possibly, M'hen their structure 

 is better understood they may have to be separated from the finer- 

 tubed organisms as a distinct group represented by G. prohlematica. 

 The latter group, including We the red's G. incrustans, a species name, 

 by the way, which is preoccupied by Borne mann's,(/) seems to show more 

 affinity towards the cyanophyceous or blue-green algae, as Seward, (k) 

 in his excellent summary of the subject, is inclined to believe ; and if 

 that be the case they are not calcareous algae in the strictest sense of 

 the term, on account of the sheaths enclosing the filaments being merely 

 encrusted, as distinguished from an actual deposition of carbonate of 

 lime within the tissues of plants like the siphoneae, and other calcareous 

 algae. (0 



FORMS OF GIRVANELLA OBSERVED IN THE VICTORIAN SILURIAN 

 LIMESTONES, AND THE SOUTH AUSTRALIAN CAMBRIAN 

 LIMESTONE. 



One of the commonest forms of Girvanella, occurring in both the 

 Cave Hill, Lilydale, and the Tyers River Limestones, is nearly related, if 

 not identical with, the G. incrustans of Wetbered.(m) This specific 

 name should be changed, however, for the reason previously 

 mentioned, and the name G. ivetheredii is now suggested. Wethered 

 described the original specimens from the Carboniferous limestone of 

 Clifton, England. The diameter of the tubes in our examples measures 

 .014 mm., being slightly larger than those described by Wethered. 

 The pellets formed by the aggregation of tortuous tubes sometimes 

 attain a length of .7 mm. 



Another form of Girvanella frequently met with in the Victorian 

 limestone is a new species which the author has named G. conjerta.{n) 

 This species is distinguished by its short, fasciculate masses of tubules, 

 with a parallel or sinuous habit of growth, rather than a continuously 

 tortuous one ; and it generally forms pellets entirely composed of its 

 own tubules, without any apparent enclosed nucleus or granule of 

 attachment, although that may be present, but of small size. The 



{j) The Siphonema incrustans of Bornemanii ('87, p. IS, pi. ii., figs. 1, 2) has 

 been pointed out by Hinde to be a true Girvanella, and as such would be referred 

 to as G. incrustans, Born. sp. Bornemann's species, however, is identical with the 

 earlier described G. prohlematica, Nich. and Eth., jvm. The still later described G. 

 incrustans of Wethered ('90, p. 280), is a species distinct from Bornemann's, 

 and by the rule of " once a sjTionym always a sjoaonym," it must be given a 

 new name. I would therefore suggest for this species Girvanella wetheredii, sp. 

 nov. 



(k) Seward ('98), p. 124. (I) Seward ('94), p. 15. 



(rw) Wethered ('90), p. 280, pi. xi., figs, la, b. (n) Chapman ('06), p. 74. 



