CARADOCIAN CYSTIDEA FROM GIRVAN. 371 



from higher up the stem (text-fig. 4). This belongs to the Petersburg Academy. I do 

 not know on what evidence specimen 4 is placed in the same vspecies, or indeed in the 

 same genus, as the others ; but I assume that material evidence does, or did, exist. 



§ 36. There is another species, R. baltica, of which the holotype is a stem- appendage 

 from B 2 (^of Gornaja Scheldicha (Jaekel, 1901, p. 665, f. 3). This appendage is 

 33 '5 mm. long, is flattened, and has a margin of thickened plates with a U section 

 (text-fig. 3). I see no difference between this and the stem-appendage in R gigas, 

 specimen 4, except size, and I suppose that the more proximal appendages in R. gigas 

 may easily have been as small as this. The species has never been diagnosed or 

 described, and the name, which occurs only in the legend to the figure, may have been 

 due to a mere lapse of memory. 



§ 37. The curious Platycystites Faberi S. A. Miller (1889, p. 272) from West 

 Virginia was regarded by me in 1900 (p. 51) as " a worn Anomalocystid of indetermin- 

 able affinities." The nature of the so-called " basal plates" and their 

 surface of attachment now suggest to me that this fossil may be one 

 of the columnar appendages of a species oi Rhipidocystis (text-fig. 5). 

 1 do not know on what grounds Dr Kirk (1911, p. 19) mentions 

 Platycystis in connection with Amygdalocystis. 



§ 38. Setting aside Rhipidocystis, the Dendrocystidae contain but 

 the single genus Dendrocystis. 



§ 39. Taxonomic History. — For the sake of completeness it may Textfig. 5. — Piaty- 

 be briefly recorded that Barrande (1887) in the arrangement of his grammatised 'from 

 Cystids followed a stratigraphical order, and, subordinate thereto, the ^- ^- Filler. Nat. 



'^ ^ size. 



order of the alphabet. 



M. Neumayr (1889, p. 412) placed Dendi^ocystis in the Echinosphaeritidae. 



F. Bernard (1893, p. 207) removed the genus to the Pleurocystidae, in which 

 Family he also included Trochocystis. 



K. A. VON ZiTTEL (1895, p. 156) referred all those genera to the Anomalocystidae. 



E. Haeckel (Oct. 1896, p. 55), while referring Dendrvcystis to the Pirocystida, a 

 subfamily of Aristocystida, suggested the establishment of a special Family for it. 



The Family Dendrocystidae was actually founded by Bather (1899, p. 919 ; and 

 1900, p. 47), and accepted by Jaekel (1901, p. 672). 



Dendrocystis. 



1859. ISyringocrinus E. Billings, Canad. Org. Rem., dec. 4, p. 65. 



1887. Dendrocystites J. Barrande, "Echinodermes . . . Extraits du Syst. Silur," 8vo, p. 219. 



Also "Syst. Silur. . . . de la Boheine," vol. 7, " Echiuodermes, Cystid^es," p. 142. 

 1896. Dendrocystis B&vr., E. Haeckel, "Ampli. und Cyst.," Festschr. Gegenbaur, vol. 1, p. 54. 



1900. Dendrocystis Barr., F. A. Bather, "Treatise on Zoology : Echinoderma," p. 47. 



1901. Dendrocystites Barr., 0. Jaekel, Zeitschr. deutsch. geol. GeselL, vol. 52, p. 673. 

 1904. Dendrocystis Barr., Delagk k Herouard, " Zool. Concrete," vol. 3, p. 408. 



§ 40. Diagnosis. — If Dendrocystis is the only genus, its diagnostic characters are 



the same as those of the Family. If, however, Rhipidocystis be included in the Family, 



