£60 BULLETIN OF THE 



Noti:. — Verrill has insisted, in his notes on Radiata, on referring Helio- 

 cidaris mexicana Ag. to Anthocidaris LiJTK., while he places Toxoeidaris 

 mexicana A. Ag. in Toxopneustes ; I do not see upon what grounds. 

 The specimens in the Natural History Society of Boston to which he refers 

 are only one of the younger stages of the long-spined variety of Echinometra 

 Michelini Des. (A. Ag.), and have nothing in common with Ileliocidaris. 

 In the second place, Anthocidaris LiJTK. is synonymous with Toxoeidaris A. 

 Ag. ; so that it is perfectly natural that the two species he quotes should 

 belong to different genera, one being a young Echinometra, the other a 

 true Toxoeidaris A. Ac, Anthocidaris Lutk. I cannot see the propriety 

 of the changes made by Verrill in the limitation of Toxopneustes, by sub- 

 stituting Euryechinus for a group of Echini, which are perfectly well known 

 by all writers on Echinoderms as Toxopneustes. For the following rea- 

 sons it seems to me, even granting all his premises, that the changes he 

 proposes are not warranted. The type of a genus at the time the Monog. 

 d. Echinides was written was never used in the restricted sense now com- 

 mon, but was coextensive with a group of species. When Toxopneustes 

 was first proposed, it was applied to a so-called typical species which 

 future investigations showed did not belong to the genus. The author 

 took the earliest opportunity possible to point out his mistake by substi- 

 tuting for it another type, and giving a description which applies not only 

 to Toxoeidaris as Mr. Verrill would hare it, but also to all the species since 

 removed as Sphairechinus by Desor. Desor, who had edited the Cata- 

 logue Riisonne, and probably knew accurately what group of Echini 

 was defined as Toxopneustes, was the first, in his Synopsis, to limit 

 Toxopneustes by removing from it certain species as Sphserechinus, and 

 restrict Toxopneustes to such forms as (T. neglectus) T drobachiensis 

 Ag., but still including the species which I have since, in the Bulletin of 

 the Museum, separated as Toxoeidaris. All these limitations, even were 

 they not accepted, have the priority over a similar limitation which Verrill 

 makes twelve years after a proper limitation of the genus has been recog- 

 nized, and eighteen years after a mistake (upon which Mr. Verrill bases 

 the whole of his proposed changes) has been corrected by the author him- 

 self; nothing, moreover, is gained in accuracy by the change proposed by 

 Verrill, T. tuberculatum being probably only a nominal species, and one 

 concerning which we have, at any rate, no authentic information sufficient 

 to form the basis of a sweeping reform. At the present rate of retrospec- 

 tive application of the laws of priority, we are fast drifting into the most 

 absurd anachronism by applying the present condition of our knowledge 

 of any group to works written twenty or thirty years ago in an entirely 

 different spirit, when the idea of type, genera, etc. had a totally distinct 

 signification from what it has at the present day. 



