204 ?. HERBERT CARPENTER. 



enterocoel, as must be the case if these structures are homo- 

 logous with the similar and similarly placed parts in the 

 Crinoids. 



POSTSCRIPT. 



1. Figs. II and vii in Part I are described as ''after 

 Loven." I much regret that; owing to an inadvertence on 

 my part, the madreporite was omitted from Fig. ii (Apical 

 system of Salenia). Its proper position would be in the 

 genital (3) at the south-west corner of the figure. 



It should also have been stated that both Figs, ii and vii 

 are inverted with respect to the positions in which they are 

 given by Loven. This was done in order to bring them into 

 positions corresponding to those in which the Crinoids are 

 usually figured, viz. with a radius due south (Figs, iii — vi). 

 The anus in Loven's own figure of Saleiiia (Etudes, pi. xxi, 

 fig. 177) is south-east, and the madreporite north-east. 



I am anxious to rectify these omissions, as it has been 

 represented to me that my diagrams of Loven's figures would 

 give to the reader an incorrect idea of his views of the whole 

 Echinoid body, for which I should be exceedingly sorry. 



2. In the note to pp. 369 — 70 of Part I, I have commented 

 upon Agassiz' not mentioning Dr. Carpenter's descriptions 

 of the young Comatula in the second issue of the ' Embryo- 

 logy of the Starfish.' I fear, however, that I did not make 

 it sufficiently clear that Agassiz' memoir remained sub- 

 stantially as it was written thirteen (now nearly fifteen) 

 years ago ; and that the notes " on the points where additions 

 have been made by subsequent investigations " were added 

 merely " for the sake of calling attention to the present 

 condition of the subject." In one of these notes, however, 

 Agassiz implies his entire acceptance of Loven's opinions 

 respecting certain homologies (from which I am, unfortu- 

 nately, obliged to differ), although he was presumably 

 acquainted with Dr. Carpenter's observations, which do not 

 altogether accord with the opinions in question. It there- 

 fore seemed to me that Agassiz was taking rather a one- 

 sided view of the present condition of the subject in speaking 

 of Loven as having ''most thoroughlij proved" these homo- 

 logies, despite Dr. Carpenter's observations to the contrary, 

 and in not mentioning these last at all. If I have in any 

 way been unfair to Agassiz, for whose Echinoderm-work I 

 have naturally the very greatest admiration, I here tender 

 him my apologies. 



3. It will be understood, I hope, that the presence of a 



