264: BULLETIN OF THE 



Lytechinus variegatus A. Ac, Bull. M. C. Z., No. 2. 



8vn. Lytechinus carolinus Ag., Bull. M. C. Z., No. 2. 



" " atlanticus A. Ac " " " 



Echinus varicgatus I!av, Cat. Echin. S. C. ; P.P. Foss. PI. 2,6^1. 



" " variegatus Lam., An. s. V. 

 Psilechinus variegatus Lime, Bidrag. 

 Psammechinus exoletus McCr., PI. Foss. S. C, PI. 2, fig. G. 



Soon after the publication of the second number of the Museum Bulletin, 

 Dr. Lutken called my attention to the identity of L. carolinus and L. atlan- 

 ticus with E. variegatus. The extensive series of this species collected by 

 Professor Agassiz in Brazil, the West India Islands, and dredged by Mr. 

 Pourtales, have satisfied mc of the correctness of his view, the variations 

 due to age or locality being astonishing. It has, like the common Echino- 

 metra, a great geographical range identical with it, but at the same time 

 has a somewhat more extensive bathymetrical distribution. 



Littoral, to 34 fathoms. 



Tripneustes ventricosus Ac, Agas. Cat. Ilais. 



Young sjiecimens of Tripneustes show the correctness of the analysis of 

 the arrangement of the pores made by Dr. Lutken. Each ambulacral 

 plate has only three pairs. The original Heliechinus Gouldii GiR., Proc. 

 Bost. Soc. N. II. 1850, is nothing but a young Tripneustes. 



Littoral, to 10 fathoms. 



Clypeaster rosaceus Lam., An. s. Vert. 



It is quite remarkable that of a species so common as this no young small 

 enough to show any very striking difference from the adult should have 

 been collected, while of nearly all the more common species complete series 

 of all sizes were obtained. 



Littoral, to 5 fathoms. 



Stolonoclypus prostratus Ac, Bull. M. C. Z., No. 2. 

 Syn. Clypeaster prostratus Lime, Bidrag. 



This genus is distinguished from the true Clypeaster by the character of 

 the internal pillars connecting the actinal and abactinal part of the test, 

 which is totally different, in all the Hat Clypeastroids allied to Clypeaster 

 placunarius Lam., from that of Clypeaster rosaceus Lam., being slender, 

 often needle-shaped points, instead of heavy, solid columns, as in true Clypeas- 

 ter. Rhaphidoclypus cannot be maintained ;is an independent genus ; it is 

 only the y r oung type of Stolonoclypus which presents some striking peculiari- 

 ties, and the species upon which the genus was based will probably turn out to 



