490 Observations on the 



about seven lines ; from this to the central point of diver- 

 gence, about two and a half lines ; and from the latter 

 point to the end of one of the branches, twelve lines. The 

 other branch was apparently about the same length, but is 

 broken. The two branches are of about equal size ; the 

 diameter of each just above the point of divergence being 

 about the same as that of the main tube or proboscis be- 

 low that point, which is there about the usual size. 



Another specimen of the same genus, but of an unas- 

 certained species, showing only the upper part of the 

 dome, measures one inch from the base of the proboscis 

 to the point of junction of the two diverging tubes. 

 These are both broken ; but what remains indicates that 

 they were each about an inch in length, of equal size, 

 which is about half that of the main tube just below the 

 junction, where a cross section would be elliptical. The 

 main tube, or proboscis, is of about the usual size at the 

 base, but it gradually enlarges towards the junction, by 

 the irregular interposition of numerous small plates be- 

 tween the larger ones. 



I am not fully satisfied that these instances are not 

 both the result of accidental development. The manner 

 of divergence of the tubes, it is seen, is not quite the same 

 in both cases, though it is probable that the specimens 

 belong to different species. The interposition of the small 

 plates in the structure of the lower part of the tube in the 

 second instance has the aspect of being abnormal. This, 

 with their rare occurrence, and the supposition that the 

 former specimen belongs to the species A. Verneuiliamis, 

 which is known to have a long, single proboscis, would 

 seem to indicate that they were so, at least to some 

 extent. 



This view may have a still further corroboration in the 

 following instances, as well as the known recuperative 

 powers of the crinoidea, in sustaining and repairing inju- 



