168 A Bare Melicertian. 



departure from those of the other Melicertians, to which we shall 

 give some consideration in a subsequent paragraph. 



The footstalk is most frequently wrinkled, and it manifests 

 very distinct muscular bands, see Plate XCVIII., Fig. 1 ; but not- 

 withstanding the presence of these, they do not produce sufficient 

 contraction of the stalk to enable the animal to withdraw itself 

 within the vagina without producing folds in the footstalk, as shown 

 by the rough sketch, Plate XCVIII., Fig. 5. The integument, 

 which is corrugated all along the footstalk, ascends to the corona, 

 where it forms an orifice into which the corona becomes retracted 

 by an invagination, the line of demarcation being very distinct even 

 during the eversion of the corona, leaving, however, the two re- 

 spiratory tubes the most prominent objects in view, as is the case 

 with every one of the Melicertians, whether these tubes are rudi- 

 mentary, or otherwise highly developed. 



In its retracted condition, Plate XCVIII., Fig. 2, the corona 

 manifests two distinct projecting processes beyond the setiferous 

 tubes which, though they present the same general appearance, are 

 not provided with setae, but manifest at their extremities a bright 

 red spot under the illumination of the Wenham parabola ; we do not 

 expect to find eyes in a haemal aspect as these spots are situated ; 

 beneath them there are three other processes which are less highly 

 developed, and the distance between these two upper processes and 

 the three lower ones corresponds precisely with the " pitch," or 

 distance ajjart of the annulets of the vagina, and we see that although 

 the corona is frequently protruded far above the margin of the 

 vagina, it never remains in that position for periods of long duration, 

 except in the instances of old animals, whose vaginae are coated 

 with extraneous matter, but with younger animals, the corona on the 

 act of eversion is seen to emerge somewhat above the margin, and 

 then to subside to such a position that these two processes become 

 identical with its margin, suggesting the not unreasonable notion 

 that these peculiar organs are employed in the act of constructing 

 this dehcate investment, but further investigation is necessary to 

 confirm this supposition ; it certainly seems somewhat inconsistent to 

 find that while in every other member of the Family the fabricating 

 organ is situated on the neural side, it should in this particular in- 

 stance be placed on the opposite ; but if their capacity as such 

 be truly surmised, they certainly produce an effect differing essen- 

 tially in the nature of the vagina so produced, which in this instance 

 is more brittle than viscid. 



While hastening for the press, I must conclude these obser- 

 vations with a cursory notice of the action of the marginal cilia, 

 which, from the tardiness of their action in this particular Form, offer 

 every opportunity for correctly appreciating their action, and of 

 representing them on a drawing, though it is of course impossible 



