40 SMITHSONIAN INSTITUTION 



FURTHER REMARKS UPON THE FIXED PINNULES 



The study of the fixed pinnules in Scyphocrinus, as described in the fore- 

 going pages, led me to review the facts bearing upon analogous structures in 

 other genera, with some curious results : 



In 1878 Wachsmuth and Springer 1 called attention for the first time to 

 certain openings in the test of crinoids located near the base of the arms 

 " pierced through at the edge of the plate and enclosed by the abutting margin 

 of an adjoining plate." Those then described were observed in Eucladocrinus, 

 and it was stated that they are also found in Batocrinus, Actinocrinus, etc., 

 and " within the false arms of Ollacrinus " {Gilbertsocrinus) . It was suggested 

 that they might have respiratory functions. 



In the Revision of the Palaeocrinoidea, Part I (1879), p. 11, and 

 Part II (1881), pp. 51-53, we discussed these openings at length, giving to 

 them at the latter place for convenience the term " respiratory pores." After 

 stating the possibility of their being respiratory or ovarian openings, we 

 observed (p. 52): "There are objections to this, and another interpretation 

 is at least possible. From what we now know of the ontogeny of the Palaeozoic 

 crinoids, we are inclined to think that the pores may have been originally 

 pinnules, which with progressing growth were soldered into the body." We 

 suggested the desirability of tracing the pores in genera like Glyptocrinus, 

 "in which the fixed pinnules retained their forms after they became fixed"; 

 and we also referred to a possible analogy with the proximal pinnules in the 

 Recent crinoids (p. 53). 



In North American Crinoidea Camerata (1897), p. 35, we stated that 

 the disk in many Camerata has " small respiratory pores or slits near the 

 arm-bases, piercing the sides of the plates "; and on p. 122 we explained that 

 " the openings are always located between the rays and their main divisions, 

 a little above the arm regions," and that " in Dolatocrinus they are slit-like, in 

 Batocrinus round, and in Gilbertsocrinus at the end of a long tube." 



Bather, in Lankester's Zoology (1900), Part III, Echinodermata, p. 130, 

 confirms the observations of Wachsmuth and Springer, giving one of our 

 figures and one of his own (fig. 45) which show the form and position of the 

 slits and pores in Dolatocrinus and Batocrinus; and he says that the supposition 

 " as to the existence in Camerata of a complicated water-vascular system, is 

 supported by the connection of the internal passages with small pores near 

 the arm-bases," and that " the pores may possibly have replaced the hydropore 

 or the madreporite of certain Inadunata." 



Specimens acquired since the dates of the above-cited publications have 

 thrown new light upon the nature of these structures, and enable us, I think, 



1 Proc. Acad. Nat. Sci., Philadelphia, vol. 30, p. 248. 



