Zoological Society. 279 



their full activity till they have arrived at maturity. What sur- 

 prises me is, that in spring I find a much larger number than I find 

 now (September). I see none, for histance, in a state of infancy. 

 I may acid, that in spring it is princij)ally in a kind of reddish scum, 

 which accompanies the green matter, that I meet with the greatest 

 number of Naciculce, and that now I find less of this scum, which 

 perhaps depends upon the fact that the water in the basin is more 

 agitated in summer, — a time when tlie water is incessantly pumped 

 up for invalids. 



'* As regards the marginal striae, I offer the following remarks : — 

 M. Quatrefages, who has been at Vichy for his health, examined the 

 Algaj with me, and has endeavoured to discover if the NavicidcB really 

 possess these striae. By the help of oblique illumination, we have 

 clearly established their existence, at least in some individuals. We 

 are not certain that they are present in all, for on some we have seen 

 them distinctly on one side only and not on the other, while in other 

 individuals we have not been able to discover them on either. I 

 cannot doubt then, that at least a certain number of Navicidcs do 

 not present striae, though they are perceptible sometimes on either 

 margin, sometimes on one only. jM. Quatrefages, equally with 

 myself, has observed the movements which I have described. Finally, 

 the endochrome in the living organism is not green but yellow, ex- 

 actly, in fact, as you see it in the dead specimens." 



Hoping that the worthy author will be indemnified for the con- 

 siderable outlay which the j)ublicatiou must have cost him, we com- 

 meud this work to the attention of our botanical friends. 



PROCEEDINGS OF LEARNED SOCIETIES. 



ZOOLOGICAL SOCIETY. 



March 13, 1855. — Dr. Gray, F.R.S., Vice-President, in the Chair. 



An Arrangkment of the Families of Echinida, with 



Descriptions of some New Genera and Species. 

 By Dr. John Edward Gray, F.R.S., V.P.Z.S., P.B.S. etc* 



!MM. Agassiz and Desor have given the generic characters and a 

 list of the species of Echinida, but do not divide the genera of the 

 normal division into famiUes. I propose to divide them into the 

 following groups. 



The Echinida acrncijsfos, or those which have a vertical dorsal 

 vent, a regular globular body, with an inferior central circular mouth, 

 armed with conical jaws, furnished with five elongate acute teeth, and 

 with the ambulacra forming continuous vertical bauds from the mouth 

 to the vent. They may be divided into the following families. 



I. Tubercles of spines perforated ; spines elongate ; body circular. 

 Fam. 1. Cidarid.e. 

 Ambulacra narrow, formed of double pores ; interambulacral 

 plates few, with a single large tubercle ; spmes thick, solid. 



