385 
Dendy & Hindle, indicate that this species is distributed, like 
the preceding species, all round the coasts of New Zealand. 
I fully agree with Becher that this species is no true Rhab- 
domolgus. H. L. Clark expresses the opinion that it is derived from 
Trochodota by loss of the wheels and the sigmata. I think it beyond 
doubt that Clark is right in this suggestion, and I can give some 
proof of its correctness. In the specimen from Takapuna Beach, 
which I am otherwise unable to distinguish from the Plimmerton 
specimens, I have found a few hooks in the skin. In one of the 
two specimens from Plimmerton, infested with parasitic snails, I 
even find both hooks and wheels. Now, this specimen is a very 
small one and in a very poor condition, perhaps because of the 
parasites, and the identification is not certain; but as it does not 
at all look like the specimens of Trochodota Dendyi, found at the 
same locality, I think it rather probable that it is really a spe¬ 
cimen of Kolostoneura which has, through the influence of the 
parasites, developed the calcareous bodies of its ancestor. 
If, then, we have a separate genus, Ånapta, for the Synaptas 
without anchors, another genus, Achiridota, for the Chiridotas with- 
1 out wheels, we should, consequently, have a separate genus also 
I for the Trochodotas without hooks or wheels, and we must there 
I accept the name Kolostoneura, proposed for it by Becher, even 
I if we may regret that he did not use the name analogous to Ånapta 
' and Achiridota which he had first planned to use. Asigma, but one 
which does not a priori convey any idea at all of its relationships. 
j The name Kolostoneura refers to the statement of Dendy&Hindle 
I that the radial nerve disappears even before reaching the level of 
' the calcareous ring. But I cannot help expressing some doubt as to 
I the general validity of this statement; at least, I find in some sec- 
tions from the middle of the body of a specimen of Kolostoneura 
! the radial nerve quite distinet in places, such sections recalling very 
I mueh the fig. 18, Taf. II of H a m a n n’s“ Histologie d. Echinodermen’', 
: which shows a transverse section of the body wall, with the radial 
I nerve, of Synapta (Labidoplax) digitata. It has very mueh the ap- 
pearance that the nerve lies wilhin the layer of circular muscles, 
' with muscular substance both externally and internally to the nerve; 
» this might well account for the faet, that the nerve is quite indi- 
stinet in places. I must content myself with these indications, this 
i Vidensk. Medd. fra Dansk naturh. Foren. Bd. 79. 25 
