CALAMOCRINUS DIOMED^E. 



inedj to the outer edge of the old joint below it. This young lobed upper 

 joint recalls the uppermost quinquelobular joint of Calamocrinus. But in 

 Cyathocrinus this disk is ten-lobed, and distinctly grooved and ribbed radi- 

 ally, while it is not so in the young joint of Calamocrinus. 



In Glyptocrinus plumosus, Hall* figures the top stem joint of the column 

 as dome-shaped. 



In Pacht'sf observations on Dimcroerinites (Taxocrinus) oligoptilus, I find 

 on Plate I. Fig. 2'. an excellent figure showing a transverse section of the 

 basal ring with its mode of junction to the top stem joint. This joint 

 i< dome-shaped, considerably higher than the other stem joints imme- 

 diately following it. but of the same diameter. On the top of this hemi- 

 spherical joint is the pentagonal outline of the axial canal. There are 

 no infrabasals, the radials themselves come nearly in contact with the stem, 

 ami are well separated by the basals, upon which rest five large inter- 

 radials, followed by smaller interradials which unite the edges of the arms 

 to the distichal axillary, thus forming a deep calyx, the parts of which 

 differ in no wise from that of Calamocrinus except in unimportant struc- 

 tural features. 



The figures given by Meek of some species of Platycrinus (Geol. Survey 

 of Ohio, Vol. II. Plate XI.) indicate that new stem joints are intercalated 

 between the older ones in the upper part of the stem, as also in Actino- 

 crinus. In Forbesiocrinus (Ibid., Plate XII.) and Zeacrinus the very upper 

 part of the stem is made up of narrow new joints, while in Poteriocrinus 

 the new joints appear on a larger part of the stem. 



Yon KoenenJ has given figures of the upper part of a stem of Encrinus 

 liliiformis, showing the grouping of the new joints extending across the 

 stem intercalated between the older ones, as well as the younger joints, 

 which as yet reach the edge of the stem only in one or two places (Plate. 

 Fig. 10, a, b, c, d). In Calamocrinus these new joints extend to a, Plate 

 XVII. Fig. 8, and to e, on Plate XV III. Fig. 2. 



The figures given by Beyrich§ (Plate I. Fig. 12, and especially Plate II.) 

 show that in the very upper part of the stem only are new joints formed, 



* Palaeontology of New York. Vol. II. Piute 41, Fig. 2". 



t Pacht, II., Verlian.il d. Kaiserl. Russ. Mineralog. Geseil. zu St. Petersburg, 1852-53 (1852). 



{ A. von Koenen, Beitrag zur Kenntniss der Crinoiden des Musehelkalks, Abhandl. d. Konig. 

 Geseil. d. Wis-, zu Gottingen, 1887, XXXIV., p. 13. 



§ Ueber die Crinoiden des Musehelkalks, Abhandl. d. Konigl. Akad. d. Wissen zu Berlin, 1S57, 

 No. 1. 



