218 Messrs. E, Etlieridge, Jim., and P. H. Carpenter on 



piece than in the lower and mnch thinner nnderlancet-piece, 

 whicli we have also found in Orophocnnns [Codonites). The 

 former corresponds to the perforate lancet-plate of Granato- 

 crinus, which is the only subambnlacral plate figured, by 

 Wachsmuth and Springer in G. Nonvoodi] so that in this 

 respect our observations appear to be in accordance with 

 theirs. 



According to Hambach* there is also " a longitudinal duct 

 or vessel resting in the concave furrow of {i. e. beneath) the 

 lancet-piece, and running from the apex of the ambulacra! 

 field to the summit, where it connects with a circular duct 

 (cesophageal ring ?) surrounding, on the interior side, the 

 central orifice or annnlus centralis.'''' 



But no mention is made by Hambach of the particular 

 s])ecies in Avhicli this second canal occurs — though, so far as 

 we can judge from the figure to which he refers in connexion 

 with the above passage, he appears to be speaking of a Pen- 

 tremites. In this case he must have seen canals both in the 

 lancet-plate and in the underlancet-plate of this type ; while 

 Wachsmuth and Springer have only seen the latter, and we 

 have only been able to make out the former, viz. tliat within 

 the lancet-plate. 



We believe it to have lodged the radial water-vessel. In 

 Pentremites and Oropliocrinus^ which have two subambnlacral 

 plates, there is an opening at the proximal end of each ambu- 

 lacrum, between the edges of two adjacent oral plates and 

 the end of the underlancet-piece. It was first discovered and 

 figured in Pentremites by Waclismuth and Springerf, whose 

 observations we are glad to be able to confirm. In Granato- 

 crinns its distal side is incomplete, owing to the absence of an 

 underlancet-]Diece. The vessel contained in the canal within 

 the lancet-plate passed downwards through this opening on its 

 way to join an oral ring. By careful grinding down of the 

 summit of well-])reserved S])ecimens we have been able to 

 demonstrate the presence of this organ and its connexion with 

 the canals within the lancet-plates in the following species — 

 Pentremites jiyriforniis and P. hurlingtonensis ^ Granatocrinus 

 Norwoodi and G. elUpticus^ ScJiizohlastus Sayi, Pentremitidea 

 d''ArcJiiacij Oro]iliocrinus inflatus and 0. steUifbrmis, and 

 Codasier trilohatus. We venture to think that there can be 

 but little doubt as to its being the water- vascular ring ; but 

 we cannot say whether it is identical with the " circular duct 

 (cesophageal ring ?) " described by Hambach {, as his state- 



« Lo(\ cit. p, 151. t Revisiou, part i. pi, iii. fig. 4. 



\ Luc. cit, p. 151. 



