•_'44 Nbtt on LdverC* ArticL on " LeaMa mirabUis, Gray." 



twecn the two extremities of the horseshoe-shaped ambulaeral 

 furrows, in the centre of the disc. In one case the mouth (a 

 very minute opening in both instances) being central, while in 

 the oilier the mouth is eccentric at the point of confluence of the 

 ambulaeral furrows, but in the middle of the horseshoe-shaped 

 curve the anus being central. 



It seems to me that Loven's figures of the ambulaeral fur- 

 rows of SpoBhronttes show that, as far as we can trace the fur- 

 rows, they formed, as in Actinometra, an open horseshoe-shaped 

 curve, and that the mouth must have been placed in the 

 middle of this curve, at a point corresponding with its position 

 in Actinomelra, opposite the base of the arm placed near the 

 middle of this curve. That is, I suppose, that in this genus 

 as in Comalula, and as in all recent Crinoids known, there 

 was a leathery actinal membrane extending along the arms, 

 covering the central part of the disc, and in this were the ambu- 

 lacral tubes, the soft parts forming a portion of the anal proboscis, 

 and the minute mouth itself having a structure similar to that of 

 our recent Antedon and Aclinometra, while theopening covered by 

 plates is nothing but the anal opening, wc find in these Crinoids 

 an embryonic feature of all young Comatvla retained bv the pre- 

 sence of one or more anal plates. This would give us an ex- 

 planation of the structure of Sphasronites and of other Cvstideans 

 perfectly in accordance with the anatomical features of living 

 Crinoids, and Prof. LoveVs figures of the curved horseshoe-sha- 

 ped ambulaeral furrows seem to me the strongest possible proof 

 of the complete accordance with recent Crinoids of this appa- 

 rently aberrant type. 



It is certainly somewhere along the ambulaeral furrows that 

 we must look for the mouth, but we could hardly expect to find 

 any trace of it, if, as 1 cannot help conjecturing from what we 



have in all our recent Crinoids, there was a leathery membrane 



which would form the mouth, covering these furrows, it has of 



course left no trace of its exist DO . any more than any of our 



it Crinoids would show the presence of either] a mouth or 



