218 
It may not be superfluous to state that I have found the genital 
pores perfectly distinct in a specimen of 12 mm diameter, the same 
size as the specimen of which Jackson has figured the apical 
system, and in which he did not find the genital pores (Pl. 4, 2). 
In regard to the anal plates I am glad to see that Prof. 
Jackson joins me in the view maintained by me (Echinological 
Notes III. Jan. 1911) of the conspicuous suranal plate of Saleniids 
and young Echinids, that it is a specialized, not a primitive 
feature, this plate having accordingly by no means the great mor- 
phological value, which bas been ascribed to it by Lovén a. 0. 
Professor Jackson lays some stress on the fact, that in Salenia 
and Salenocidaris the suranal plate lies "””dorsal to genital 3, while 
in Peltastes and some Acrosalenias it lies ""dorsal to ocular III.” 
I would suggest that the position of the suranal plate is in reality 
the same in both cases: what makes the difference is the position. 
of the periproct and the anal opening. In the former case it is 
eccentric in the direction of Ocular I, ås is the common condition 
in the Echinina; in the latter case it is eccentric in the direction 
of genital 5, viz. in the same direction in which the anal opening 
moves backwards in the Exocyclica. 
I may note in the briefest way such interesting points as the 
representation of the different ways adopted for increasing the 
number of tube-feet (— Jackson might there well have gone å 
little farther and mentioned that after the condition of the compound 
ambulacral platés has been reached, the increase of the number of 
tubefeet still continues and along two different ways viz. either by 
the narrowing of the compound oligopore!) (triseriate) plates accom- 
1") A. Tornquist in a recently published, very interesting paper: »Die 
biologische Deutung der Umgestaltung der Echiniden im Palåzoikum 
und Mesozoikum (Zeitschr. f. induktive Abstammungs- u. Vererbungs- 
lehre VI. 1911) uses the term ,oligopor' in quite a new meaning, 
designating that the two pores of a pair in a primary ambulaeral 
plate are placed obliquely to one another. I would decidedly protest 
against using the old familiar word in this new meaning. It may be 
convenient to have a word for designating that position of the pores ; 
but "oligopore” means in Echinology a compound plate consisting of 
three primary plates and should be kept in this sense. | 
