ABSTRACT
During the last two years the morphology of the Echinoderms has engaged the attention of several continental naturalists. Some of their observations tend to support views which I have advanced in the pages of this Journal, while others are directly opposed to them. Under the latter head come the researches of the French school into the anatomical relations of the vascular system; and it is curious that the conclusions to which Messrs. Jourdain, Koehler, Apostolides, Perrier, and Poirier have been led differ in toto from those of the German school as represented by Greeff, Hoffmann, Lange, Simroth, Teuscher, and especially by Ludwig. These last have been sufficiently described in a previous number of this Journal (vol. xxi). It is hardly time as yet to give a résumé of the observations of the French school, but one or two of their principal conclusions may be briefly alluded to.
Under this title I propose to continue from time to time the series of papers bearing on this subject, which I have already published in previous volumes of this Journal, e.g. :
I.—’ On the Oral and Apical Systems of the Echinoderms,’ part 1, vol. xviii, 1878, p. 351. II.—The same, part 2, vol. xix, 1879, p. 176. III.—’ Some Disputed Points in Echinoderm Morphology,’ vol. xx, 1880, p. 321. IV.—’ The Minute Anatomy of the Brachiate Echinoderms,’ vol. xxi, 1881, p. 169.
’Comptes Rendus,’ t. Ixv, pp. 1002-1004; t. xciii, pp. 651-653 ; t. xciv, pp. 139-141, and pp. 744-746; t. xcv, pp. 459-461. See also Perrier and Poirier, in t. xciv, pp. 658-660, and pp. 891, 892.
” Anatomie et Développement des Ophiures,” ‘Arch, de Zool. expie, et générale,’ vol. x, pp. 121-224.
” Recherches sur l’Appareil circulatoire des Oursins,” ‘Arch, de Zool. expie, et génie.,’ vol. iv, pl. xxiii, fig. 1.
“Sur l’Appareil circulatoire des Etoiles de mer.,” 1 Comptes Rendus,’ March 6th, 1882, t. xciv, pp. 658-660.
Judging from the meagre descriptions without figures, which have been published by Jourdain, Messrs. Perrier and Poirier, I strongly suspect that the real blood-vessels which have been seen and drawn by their German colleagues have escaped their notice.
Zeitselir. f. Wiss. Zool.,’ Bd. xxxiv, pl. xv, fig. 16.
Ibid., Bd. xxxvii, pp. 1-98.
This Journal, vol. xxi, 1881, pp. 184, 185, Pl. xii, fig. 14.
’ Marburg Sitzungsberichte,* 1872, No. 11, p. 164.
’ Comptes Rendus,’ t. xciv, pp. 744-746.
This Journal, vol. xviii, 1878, pp. 352-383.
“Ueber den primaren Steincanal der Crinoideen, nebst vergleichend Anatomischen Bemerkungen über die Echinodermen iiberhaupt,” ‘Zeit. f. Wiss. Zool.,’ Bd. xxxiv, pp. 318-332.
This Journal, vol. xx, 1880, pp. 322-329.
This Journal, vol. xviii, 1878, p. 358, fig. 3. I think it will be advantageous to limit the name “dorsocentral” to the central plate in the apical system of the Echinoderms, instead of using it as equivalent to the centrodorsal of the Comat-ulce. This is another structure altogether, being merely the modified top stem-joint.
“Études sur les Echinoïdées,” * Kongl. Svenska Vetenskaps Akademiens Handlingar,’ Bd. ii, No. 7, p. 65, sqq.
’ Embryology of the Starfish,’ pp. 62, 63.
’Revision of the Palæocrinoidea,’ part i, Philadelphia, 1679, p. 21.
This Journal, vol. xviii, 1878, pp. 371, 372.
E.g., those of Sir Wyv. Thomson, Dr. Carpenter, and M. Sars.
Götte’s attempt to disprove the annular origin of the centrodorsal is not a satisfactory one. Even supposing that he is right, and that the centrodorsal does originate out of five primitively separate elements, it cannot, on the views advocated above, represent the primitively simple dorsocentral of the Echinozoa.
Dyreriget, ‘En Haand. og Laerebog til brug ved hojere Laereaÿstalter,’ Kjbenhavn, 1882, p. 597.
’ Zeitschr. f. wiss. Zool./Bd. xxxvii, p. 60.
“Zur Entwickelungsgeschichte des Ophiurenskelettes,” ‘Zeitscb. f. wiss. Zool./Bd. xxxvi, pp. 181-200, Taf. x, xi.
The presence of the orals (5) in the stage represented in Fig. I some-what obscures this arrangement. It is better shown in the earlier stage represented in Ludgwig’s fig. 17, where the only oral visible is that which ultimately bears the madreporite.
These must not be confounded with the interradial plates seen by Agassiz in Ophiopholis bellis, and compared by him to the interradial plates of an Asterid (‘Embryology of Echinoderms,’ p. 18, fig. 29). The former. situated outside the radials of Ophiopholis, are really the orals ; while the latter, situated inside the radials of Asteracanthion, are the genitals. Following Agassiz, I have wrongly described the former as genitals or basals (this Journal, vol. xviii, p. 369), though his figure should have indicated bis error to me; and I am sorry to say that this statement was reproduced in the ‘Comparative Embryology ‘of my lamented friend, the late Prof. Balfour (p. 469). As I did not notice the error till after reading over the proof of the chapter on Echinoderms, I therefore take this opportunity of correcting it. I believe, however, that basals are really present in Ampkiura squamata, though I should say that Ludwig expresses no opinion respecting the homology of the plates discovered by him, and must not therefore be considered as responsible for the views enunciated above.
‘Zeitschr. f. wiss. Zool.,’ Bd. xxxiv, pp. 315-318.
Ludwig, for embryological reasons, regards the anal interradius of a Starfish as anterior. Abler pens than mine will doubtless discuss this question. I have simply “onentirt “the Starfish in correspondence with the natural position of a Crinoid.
Loc. cit., p. 50, Taf. iii, fig. 41.
‘Studien über die Entwickelung der Echinodermen und Nemertinen,’ ‘Mém. St. Petersb. Acad.,’ viie serie, tome xiv, No. 3, pl. xii, fig. 1.
Loc. cit., p. 87, figs. 257, 259, 260.
’ North American Starfishes,’ pl. vi, fig. 10.
I use the word “odontophore “for convenience sake, though I fully agree with Ludwig’s strictures on the name. But it is at any rate better than “Erstes intermediare Interambulacralstück.” If it represents the mouth-sbields of Ophiurids and the orals of Crinoids, why not call it an oral at once ?
“Note sur les Brisinga” ‘ Comptes Rendus,’ t. xcv, pp. 61-63.
