206 Transactions of the 



c, a, and a', as well as the angles of the arms and crutches, d, e, 

 and /, and also the inclination of the axis imposed by such a 

 position, when by projecting horizontal lines from these points to 

 intersect the coincident vertical lines continued from Fig. 1, we see 

 in Fig. 2 where the extremities and bifurcations disagree, and on 

 Fig. 3, as projected, where they are identical with the several points 

 on the plan above, which last is submitted as a correct representation 

 of the spiculum in the position assumed. 



The displacement of the several arms and points in Fig. 2 is 

 just such as would be produced by the employment of a compressor 

 for the purpose of examination, and under such circumstances I 

 presume it has been traced by the aid of a camera lucida ; and 

 admitting this to be a correct drawing of the form which was seen 

 " under the microscope," I must beg to submit that it is not a 

 correct representation of that which exists in the tissues of the 

 animal. 



In the next place, 1 have to refer to a rotifer, CEcistes inier- 

 medius, discovered by Mr. Henry Davis, and described in a paper 

 communicated by him to this Society in the year 1866, of which 

 Plate LXXXII., Figs. 5, 6, and 7, are reproductions of the 

 drawings illustrating the subject ; and a comparison of the several 

 views will show that some licence has been taken in creating the 

 figure representing the lateral view of the disk, Fig. 7, for it will 

 be seen that this is just twice as deep as it is shown to be in the 

 other two views, Figs. 5 and 6, which are consistent the one with 

 the other, and that to accommodate such an inconsistency it has been 

 found necessary to scamp the length of the tube at the top. Such 

 a lateral view as that of Fig. 7 must necessarily impose in the 

 others an outline somewhat of the form shown by Fig. 8. This 

 discrepancy will fully account for the fact of a drawing of the 

 animal by Mr. Slack having, when placed beside it at the reading 

 of the paper, " differed widely " from the drawing furnished by the 

 author. And I must beg, with all due respect, to dispute the 

 assertion that " both portraits are correct." 



On the other hand, we have examples in which the authors 

 manifest a precognition of the principles I desire to inculcate, in 

 the exquisite drawings of Mr. Gosse, illustrating his ' History of 

 the British Sea Anemones and Corals ; ' and in those of another 

 order illustrating Mr. Hincks's 'History of the British Hydroid 

 Zoophytes,' and even in this last the particular delineation of 

 Cladonema radiatum, plate XI. of that work, fi-om the jDencil of 

 Mr. E. W. Holds worth, elevates it in my humble estimation far 

 above any one of the other numerous illustrations of that valuable 

 and highly interesting work. 



I do not presume myself to emulate the refinements of the 

 latter examples, but with the view to avoid the inconsistencies 



