Perignathic Girdle of Discoidea cylindrica, 235 
Form of the Echinoconide ” (Bihang till Kongl. Svenska 
Vet.-Akad. Handl. Bd. xiii. Afd. iv. no. 10), and explaining 
why he had not noticed our paper upon the perignathic girdle 
of Discoidea cylindrica, Lmk. Prof. Sven Lovén wrote that 
he could not reconcile our drawing (fig. 8, p. 56) with the 
results of his own observations upon several specimens, and 
that as he disliked animadversion he had thought it best to 
publish his figures and to leave ours alone and uncriticized. 
He also sent us his interesting paper, containing beautiful 
illustrations. 
We thank our friend very cordially for his courtesy, but 
we think that it is due to him that his discoveries should be 
placed on record in a paper which will also do justice to 
ourselves, 
We have nothing to retract or to add regarding the descrip- 
tion given by us of the specimen in the British Museum, 
Prof. Sven Lovén’s beautiful drawing shows, in addition to 
what may be seen in the specimen we studied, distinct sutur- 
ing of the interradial expansions of the girdle, some minute 
plates at the ambulacral edge of the interradial expansion, 
but one pair of pores on either side of the ambulacral median 
line, and that the outer pore of each pair is either along the line 
of the ambulacro-interradial suture or beyond it and in the 
edge of the interradial expansion. The drawing by Prof. 
Lovén (op. cit. p. 9, fig. 1) gives the impression that the 
parts of the interradial expansions next to the poriferous zones’ 
are ambulacral and therefore relics of ‘ processes ” *. 
It is perfectly evident that Prof. Lovén intended to convey 
that these relics are those of ‘ auricles” (ambulacral_ pro- 
cesses in other terminology), and, indeed, in his description 
of his fig. 2 he wrote “ Four auricles from the aboral side 
and an ambulacral pair in the middle.” 
It became necessary for us to examine other specimens, so 
as to compare our results with those of Prof. Lovén upon 
1. The position of the ambulacral pairs of pores. 
2. Comparison of the teaching afforded by the original 
specimen and by those ot Lovén. 
3. The sutures of the expansions in new specimens. 
Numerous specimens of Discoidea cylindrica were cut, and 
without satisfactory results, the girdle being absent or ruined ; 
but, thanks to Mr. Gregory, F.G.S., of the British Museum, 
we have been able to study a very fairly preserved specimen. 
* The terminology will be found explained in Journ. Linn. Soc., Zool. 
yol. xix. p. 179 (1885), “On the Perignathic Girdle of the Echinoidea,”’ 
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