248 ECHINI OF THE EASTERN COAST OF THE UNITED STATES. 



lection, taken in connection with the Museum materials, gave the means of 

 studying the changes due to growth of the following species : — 



Cidaris tribuloides. Toxopneustes variegatus. 

 Dorocidaris papillata. " pileolus. 



Diadema setosum. Hipponoe esculenta. 



Echinothrix turcarum. Eehinocyamus pusillus. 



Arbacia punctulatu. Echinanthus rosaceus. 



" pustulosa. Clypeaster subdepressus. 



Ecliinometra Van Brunti. Echinarachniaa parma. 



Strcmgylocentrotus Drobachiensis. Eneope emarginata. 



Echinus acutus. Mellita testudinata. 



" melo. " sexforis. 



" norvegicus. " longifissa. 



" gracilis. Fibularia vulva. 



Sphnerochinus granulans. Echinolampas depressa. 



Microcyphus zigzag. Echinocardiura cordatum. 



Teninoplcurus Reynaudi. Brissus unicolor. 



Temnechinus maculatus. Brissopsis lyrifera. 



Trigonocidaris albida. Agassizia excentriea. 



I ddiilit it', without the aid of the information gained by the study of these 

 young Echini, a satisfactory report of this collection could have been made. 

 The changes some species undergo are so great that nothing would have 

 been more natural than to place the two extremes of t ho series not only in 

 different species, hut often in different genera, and even in different families. 

 As a necessary consequence, the study of these young, showing what we 

 may consider differences due only to growth, will lead to the elimination of 

 numerous species and genera, and give us hereafter a much more accurate 

 basis in our limitation of genera species, and the higher subdivisions. I shall 

 always consider myself fortunate to have had the opportunity — thanks to 

 the liberality of the Superintendent of the Coast Survey — of examining this 

 collection, forming the most valuable addition to our knowledge of recent 

 Echinoids since the collections of the same order made by Stimpson in the 

 Pacific. 



The changes in the classification of the Echini, hinted at in the Preliminary 

 Report, have been carried out as far as the recent Echini are concerned, and 

 I trust that the materials I have succeeded in accumulating will form a more 

 correct standard than we have had heretofore for the determination of the 

 fossil species. The number of fossil genera has been increased to such an 



