1870.] BILLINGS — ON CRINOIDEA AND BLASTOIDEA. 193 



Fig. 12. Streptorliynchus Pan- 

 dora. A specimen bored at o by a 

 carnivorous gasteropod. From the 

 Corniferous Limestone, Devonian, 

 Canada, 



of workmanship to be precisely the same. I have the proboscis 



of an Act'uiocrlnus that is bored 

 near the base, and among the 

 fossils lent me by Mr. Wachsmuth 

 is a Codonites stelUformis, that is 

 bored through one of the ambul- 

 acra. The view I took of the sub- 

 ject in my paper, was that the gas- 

 teropod ascended the stalk of the 

 Crinoid, and thrust its proboscis 

 into the mouth of the latter. The 

 Crinoid then slowly drew its arms together and held the shell fast 

 until both died. 



A third objection is the small size of the aperture in some of 

 the species. In general, where there is no proboscis the orifice is 

 from one-twentieth to one-tenth of an inch in diameter, quite suffi- 

 cient for an animal that subsists on microscopic organisms. It is 

 stated by Meek and Worthen that where there is a proboscis, the 

 aperture is sometimes scarcely '• more than one-hundredth of an 

 inch in diameter." I believe in many such instances the tube is 

 filled up by calcareous deposits on its inside, and that when entirely 

 obstructed, either a new aperture is opened out in the side of the 

 proboscis, or that the animal died. In Mr. Wachsmuth's collect- 

 ion, I saw a specimen with a second aperture in the process of 

 formation. A ticket was attached to it by him, giving this ex- 

 planation. I am also informed that in some of the existing 

 species of Antedon " the mouth is an exceedingly minute aper- 

 ture." 



A fourth objection is thtjt the aperture is so situated that 

 the arms could not have conveyed food to it. It is however 

 proved by Dr. W. B. Carpenter, that in the recent Crinoids the 

 arms are not prehensile organs. The animal while feeding remains 

 motionless, attached by its dorsal cirrhi to a stone, shell, or other 

 object on the bottom. Its arms are either stretched out to their 

 full length, or more or less coiled up, but quite immovable. As 

 Dr. Carpenter's remarks have a very important bearing upon the 

 subject, I shall take the liberty of quoting the following : — 



'' Whatever may be the purpose of the habitual expansion of the 

 arms, I feel quite justified that it is not (as stated by several 

 authors whom I cited in my historical summary) the prehension of 

 food. I have continually watched the results of the contact of small 



