EcMnodermata^ hy Prof. F. J. Bell. 439 



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. 



Echinus. 



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) Echinus acufus, (2) Echinus 

 microstoma, and (3) Echinus esculentus ; I 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 E. elegans. 



Echinus acutus, Lamk. 



First, as to the matter of the name I follow Prof. A. 

 Agassiz (1872) in regarding E. Flemiiigi as .synonymous with 

 E. acutus ; Sir Wyville Thomson records E. Flemingi, Ball, 

 but not E. 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 E. acutus over (see p. 744), 



E. acutus was obtained by Mr. Green at 55, 110, 500 fath, 

 .£'. ocM^Ms 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 j for 

 example, in a " typical example " one of the longest spines 

 measured 37 millim., and in the variety 4G 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. 



