196 . THE CANADIAN NATURALIST. [June 



orifices. This appears to me in the highest degree improbable. 

 In the recent Crinoids the grooves of the arms are occupied by 

 four sets of tubes, which Dr. Carpenter calls the caeliac, the sub- 

 tentacular, the ovarian and the tentacular canals. None of them 

 communicate with the stomach. It is impossible that the most 

 minute particle of food could gain acess into the interior of the 

 animal through any of them. The structure of the arms of the 

 paleozoic Crinoids is such, that we must presume that their grooves 

 were occupied by similar tubes, which passed through the ambul- 

 acral orifices into the perivisceral space. In the Cystidea and 

 Blastoidea the respiratory organs were not situated in the grooves 

 of the arms, and the ambulacral orifices were therefore only ovarian 

 in their function. The improbability of their being also oral 

 apertures is best shown by an illustration. 



In fig. 13, is represented (natural size) the apertures of the 

 13. 14. smallest specimen of Caryocrhius ornatus 



in our collection, selected for the present 

 purpose because in the young of this spe- 

 cies, the valvular orifice is larger in pro- 

 portion to the disCj than it is in the adult. 

 It is in this specimen, about one- third of the whole width of the 

 apical disc, while in a full grown Carijocrinus it is only one-ninth 

 of the width. The same proportional size of the mouth accord- 

 ing to age, occurs in the Antcdon rosaceus. The valvular mouth 

 at first is as wide as the disc. But as the age of the animal in- 

 creases the disc grows wider but the mouth does not. The ova- 

 rian pores in Caryocrhius are however as large in the small ones 

 (once they make their appearance) as they are in those full grown. 

 For recognizing these as ovarian pores we have the following 

 reasons: — 1. T he v are situated at the bases of the arms where 

 the ovarian tubes must pass from the grooves into the perivisceral 

 cavity. 2. When compared with the ovarian pores of a Sea-urchin 

 they have the same size, form and aspect. Fig. 14 represents the 

 ovarian pores of the Sea-urchin Toxopneustes DrohacJiiensis Ag. 

 natural size and arrangement. It may not appear at first view 

 that this latter comparison has any probative efl"ect. But it has, 

 in this way. If these apertures in Caryocrinus were large open- 

 ings a line wide, as are some of the ambulacral orifices of the 

 Crinoids, I would say that they were unlike true ovarian aper- 

 tures. 



According to the new theory, this Echinoderm, Caryocrinus 



