36 PROF. AGASSIZ ON THE SYNONYMY OF ECHINI. [Jail. '20, 



with the first livraisou, containing the Salenies (1838). The special 

 titlepage of this first monograph was preceded by a Preface, with 

 separate paging in roman numerals. Tke cover of the second 

 livraison (1841) says " contenant les Scutelles ;" and nothing else 

 relating to the contents is printed on it. 



The special titlepage of this second monograph (Scutelles) is, like 

 that of the first livraison, preceded hy an Introduction, the " short 

 essay " in question, headed " Observations ...."; this has, Hke the 

 Preface of tlie first monograph, a separate paging, but in arable 

 numerals. The contents of tliis so-called essay, in spite of the 

 headiu'T, show plainly enough that it was not considered at the time 

 fts a special essay, but that it was simply an Introduction to the 

 livraison'. It was always so regarded by Professor Louis Agassiz ; 

 he invariably spoke of it as ' I'lntroduction de la Monographic des 

 Scutelles.' Nor was he alone in so regarding it ; all writers on 

 Echinoderms who have quoted these independent monographs (as I 

 have done in the Revision) without reference to the number of the 

 livraison, but entirely from the contents as printed on the cover, 

 always quote this " essay " as ' Monographic des Scutelles (Intro- 

 duction).' I have only followed their example ana that of Professor 

 Agassiz himself. 



It is, perhaps, unfortunate that this part of the ' Monographic des 

 Scutelles ' should be quoted in that way, on account of the Intro- 

 duction following the special titlepage and dealing with the group of 

 Scutellae in general. But it does not justify Mr. Bell in assuming 

 that he corrects a grave error and gives information not to be found 

 in the Revision. 



Mr. Bell states on p. 656 that he discovered only accidentally 

 the history of this "essay," because he was fortunate enough to 

 obtain an unbound copy of the four parts of the ' Monographies 

 d'Echinodermes ' as originally pubhshed. It is rather strange that 

 so exacting a critic as Mr. Bell should be dependent for his inlor- 

 mation (which is after all incomplete) upon a bookbinder. 



Notwithstanding all Mr. Bell has said or may say, the fact still 

 remains that in July 1841 the name Tripneustes first appears, as is 

 stated in the Chronological List of the Revision, and that it did not 

 appear for the first time, as Mr. Bell maintains, in the Preface to 

 Valentin's ' Anatomic du genre Echinus,' published in the following 

 December. 



Mr. Bell will perhaps learn as he goes on that Professor Louis 

 Agassiz omitted to recognize several of the genera first named by him 

 in this same Introduction to the ' Monographic des Scutelles,' and 



' Separate copies of the Preface of tlie first livraison of tlie ' Monographies 

 d'fichinodermes ' were distributed as a prospectus, to obtain subscribers for the 

 work ; the heading on the titlepage being " Monographies d'Echinodermes 

 (Extrait de la premiere livraison de cet ouvrage, qui renferme une Mono- 

 grapliie des Salenies yivantes et fossiles)." 



In a like manner and for the same purpose separate copies of the " short 

 essay" (Observations . . . .) were also distributed with a corresponding head- 

 ing : — " (Extrait de la seconde livraison de cet ouvrage, qui renferme une 

 Monographie des Scutelles virantes et fossiles)." 



