Echinodermata, by Prof. F. J. Bell. 439 
Diam. of test. Diam. of mouth. Diam of apical area. 
millim. millim, millim. 
ACr 125 36 20 
By). 110 34 18 
C=: 100 32 18 
1D) ¢ 95 24°5 15:5 
Ry. f 80 21 14:5 
The specimens A and B were opened ; before this was done 
a small hole was made and spirit injected, so as to mode- 
rately distend the test ; the height of A was then 40 and of B 
30 millim. 
ECcHINUS. 
As will be readily supposed by those who know the diffi- 
culties always presented by a number of northern specimens 
of this genus, I have had to puzzle long over the large num- 
ber of examples which Mr. Green collected. At this moment 
the matter seems to me clear enough, but I am by no means 
confident that if I had taken the set of specimens in a different 
order I should not have arrived at a different conclusion. I 
seem to have before me :—(1) Hchinus acutus, (2) Echinus 
microstoma, and (3) Kehinus esculentus ; | have had to detail at 
what will, I fear, be a wearisome length the doubts and diffi- 
culties I have experienced as to a fourth species which seems 
to me to be probably LZ. elegans. 
Echinus acutus, Lamk. 
First, as to the matter of the name I follow Prof. A. 
Agassiz (1872) in regarding /. Hlemingt as synonymous with 
E. acutus; Sir Wyville Thomson records L£. Flemingi, Ball, 
but not . acutus, as having been taken by the ‘ Porcupine.’ 
Thomson gives no reason for the adoption of Ball’s name, 
though it is clear from p. 722 of his memoir that he was 
acquainted with Mr. Agassiz’s ‘ Revision ;’ in the matter of 
nomenclature, however, these two authors are often at variance, 
and Thomson holds 4. acutus over (see p. 744). 
E. acutus was obtained by Mr. Green at 55, 110, 500 fath. 
HH. acutus certainly varies considerably ; there is one well- 
marked variety in which the spines are a good deal longer 
than usual and bright crimson at the base when dry; for 
example, in a “ typical example” one of the longest spines 
measured 37 millim., and in the variety 46 millim., both 
being from the same haul of the dredge. This long-spined 
variety was found of different sizes, the proportionately longer 
spines being visible even in quite moderately sized specimens. 
