CALAMOCRINUS DIOMED^. 59 



and that they soon assuino thoir ultiuuito shape, gradually passing into the 

 lower joints where the joints are identical, or nearly so, while in the 

 upper part, where new joints are fbrnied, they are not. Beyrich and 

 von Koenen seem to have succeeded in tracing a regular order of appear- 

 ance of the new joints. I could only say that from three to four new 

 joints are intercalated between any two original sutures of that part of 

 the stem where they are added by the gradual increase in height. I 

 cannot understand why Beyrich asserts {loc. clt., p. 7) that in the youngest 

 stages the stem could be divided into two parts, in one of which the 

 lower joints never possessed the flat shape of the young joints of the 

 uppei- extremity, and vice versa. This certainly is not the case in Calamo- 

 crinus, and there seems to be no valid reason for the interpretation given 

 bv liJeyrich to the difference in structure he observed in the upper and 

 lower parts of the stem of Encrinus. 



Hall figures * the upper part of the stem of Dendrocrinus longidactylus, 

 showing plainly the new joints forcing their way to the surface between 

 the older ones. 



In Ichthyocrinus young joints appear to be most numerous also in the 

 part of the stem immediately below the calyx. 



In Poteriocrinus, Cyathocrinus, Platycrinus, Actinocrinus, and other 

 palteozoic Crinoids, the same is the case, so far as can be judged from 

 the numerous figures of parts of the stem which have been published in 

 the Palaeontologies of New York, of Illinois, of Iowa, and of Ohio, and by 

 Angelin. 



De Koninck and Le Hon t figure a stem joint of Poteriocrinus showing 

 the same structure of the axial part of the stem which we find in the 

 upper joints of Calamocrinus. 



In the descriptions and figures of Crinoids given by Hall and Whitfield 

 of the Crinoids of the Waverly group (Geol. Survey of Ohio, Palaeontology, 

 Vol. II. Plate XL), the upper part of the column of Actinocrinus consists 

 of alternating or of uniform joints, soon passing into a region of the column 

 in which the joints are alternately thick and thin, and rapidly passing to 

 thick joints separated by three or four thinner joints, which in their turn 

 may be wide or narrow, the thicker joints projecting beyond the edge of 

 the column. 



* Paleontology of New York, Vol. II. Plate 42, Figs. 7, 7". 



f De Koii'nck and Le Hon, Ciinoides du Terrain Carbonifere de la Belgique, 1854, Plate 1. Fig. 1. 



