1881. J NATURAL SCIENCES OF PHILADELPHIA. 201 



each arm, and forming thereby, between the interpalmar fields, a 

 smaller intrapalmar' one similarly constructed. 



A calcareous lining, such as described, has been observed by us 

 with slight variations in Batocrinus, Dorycrinus, Teleiocrinus, 

 (Meek and Worthen's Strotocrinus B), Agaricocrinus and Eretmo- 

 crinus^ and probably existed in many other genera. In the 

 Actinocriniles, or tj'pical Actinocrinidre, the inner framework 

 was either less developed, or was of a more perishable nature. In 

 the genus Actinoci'inus it is indicated on the inner floor of the 

 test by little roughened places, which we take to be traces of the 

 pillars which supported it. In Physelocriniis even these have not 

 been observed, but it is a characteristic feature of that genus, 

 that the plates of the calj^x have along the sutures at each angle 

 verv distinct indentations resembling pores, which give to the 

 outer surface of the test almost the appearance of the inner plexus 

 in species of Batocrinus or Dorycrinus. Whether there was any 

 communication with the visceral cavity' through these indenta- 

 tions cannot be ascertained from the fossil. The test at these 

 points is exceedingly' thin and transparent, but we have never 

 detected an actual passage. It must also be noted that the vault 

 in that genus has similar indentations, but these, contrary to the 

 others, open out from the inner floor of the test, being arranged 

 along the radial grooves, not interradiall^'' as those along the 

 calyx (PI. XIX, figs. 5 and 16). In Strotocrinus^ an internal 

 framework has been observed in connection with the cal^-x, but 

 none with the vault, and its typical form had apparently, like 

 Physetocrinus, slight indentations along the inner floor of the 

 vault. 



The general internal structure indicates a concentration of 

 organs toward a point beneath the centre of the vault, in front of 

 the anus, but not to the anus itself. The latter is situated distinctly 

 outside the radiation, i. e., interradially. The grooves which we 

 have noticed in the vault were figured by De Koninck and Lelion in 

 their Recherches Crin. Carb. Belg., but they seem to have regarded 

 them as muscular impressions. Billings, in the third and fourth 

 Decades of the Canada Geological Report, was the first to treat 



' The term " i/ii<;rpalmar Felder " was used by Joh. Mtiller for the " in- 

 terradialen Felder zwischen den Tentakelvinnen im Perisom des Penta- 

 crir.us, ' /«^?'rtpalmar Felder ' for the interdistichal Felder" (jMonatsber. 

 Berl. Acad. 1841, p. 218;. 



