60 CALAMOCRINUS DIOMED.E. 



In Platycrinus the upper part of the stem is also made up of alternating 

 thick and thin joints. 



In Forbesiocrinus the upper part of the column is widest, gradually 

 tapering, and made up of thin flat disks, passing into the stem with alter- 

 nating thick and thin disks. 



Hall figures, on Plate A 41 of the second volume of the Palaeontology 

 of New York, the calyx and upper stem joints of Clostei'ocrinus elongatus. 

 The upper part of the column is spreading, and the upper face of the top 

 stem joint is conical, much as we find it in some of the Apiocrinid«. 



On Plate 42, Fig. 7 c, Hall also figures the expanding upper part of the 

 column of Dendrocrinus longidactylus, showing the young intercalated 

 joints, the outer faces of some of which have found their way to the surface 

 of the column. 



In Ichthyocrinus Irevis, the infrabasals, " undeveloped pelvic plates sur- 

 roundino; the centre " as Hall calls them, restin<? unon the column, are 

 figured on Plate 43, Figs. 2 f, 2 g, much as in a species of Glyptocrinus 

 sent me by Wachsmuth for examination. The spreading upper part of 

 the stem of Ichthyocrinus is made up of thin flat joints, which gradually 

 taper into thicker joints. 



In Lyriocrinus the joints are alternately thick and thin (Hall, Pal. of 

 New York, Vol. II. Plate 44); also in Lecanocrinus (Plate 45). In the 

 spreading upper part of the stem of Saccocrinus (Ibid., Plate 46), the alter- 

 nating joints are thick and thin, the former ornamented with a line of 

 granules, the latter smooth. In Car>ocrinus the stem joints are nearly 

 of the same thickness, alternating irregularly wide or narrow (Ibid., Plates 

 49, 50). 



In Homocrinus figured by Hall (Ibid., Vol. III. Pla.te 1, Fig. 8), the upper 

 part of the stem adjoining the calyx shows a few thin joints slightly wider 

 than the lower part of the column, in which the wide joints projecting 

 beyond the general outline of the column are separated by from three 

 to four slightly thinner joints (Plate 1, Fig. 5 a). 



The upper part of the column of Mariacrinus nobilissimus (Ibid., Plate 2, 

 Fig. 1) is composed of thin uniform joints, while in Mariacrinus pachy- 

 dactylus (Plate 3, Fig. 1) the upper end of the column consists of thicker 

 joints, and the column widens gradually towards the lower part of the stem ; 

 though from the figures given by Hall in Plate 3 B it is evident that towards 

 the extremity of the stem it tapers again and gives off numerous branchlets. 



