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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Echinoderma. 
Alimentary Tract of Pelmatozoa.* — Herr 0. Jaekel finds that there 
is a remarkable contrast in the structure and position of the alimentary- 
tract in Crinoidea (Jkl.) on the one hand, and Cladoidea, Cystoidea, and 
Blastoidea on the other. In the first, the gut is “ solar ” (following the 
hands of a watch), and in a simple coil ; in the others it is “ contrasolar,” 
and apparently always more complicated in its coiling. Thus the Cla- 
doidea are brought further from the Crinoids, and nearer the Cystoids 
and Blastoids. 
Anal Papillae of Caudina coriacea.t — Prof. A. Dendy finds two kinds 
of papillae around the anus of this Ilolothurian : — (1) There are five 
blunt radially-placed projections, which contain abundant spicules, and 
are mere solid processes of the body -wall, without nerves or ambulacral 
vessels. These are apparently present only in extreme youth, and may 
represent anal teeth in a vestigial condition. (2) There are five radially- 
disposed groups of anal tentacles (doubtless homologous with the tube- 
feet of typical Holothurians), containing branches of the radial nerves 
and of the radial ambulacral vessels, with loosely scattered spicules 
in their walls. The branches of the ambulacral vessels are swollen out 
to form circumanal ampullae, the function of which is evidently to assist 
in protrusion and retraction of the anal tentacles. As it seems probable 
that C. coriacea, like C. arenata , often lies buried in the sand, with only 
the tip of the tail projecting, the development of sensory tentacles is 
readily intelligible. 
Classification of Synaptidge.J — Herr Hjalmar (jstergren has studied 
numerous species of Synaptidm, and finds himself forced to suggest a 
much more elaborate classification than heretofore. 
I. Synaptime: — Euapta g. n. (6 sp.) ; Chondrocloea g. n. (13 sp.) ; 
Synapta Eschscholtz (7 sp.); Lapidoplax g. n. (5 sp.) ; Protankyra 
g. n. (20 sp.); Anapta Semper (2 sp.). 
II. Chiridotinae : — Sigmodota Studer (7 sp.) ; Chiridota Eschscholtz 
(7 sp.). 
III. Myriotrochinae : — Myrwtrochus Steenstrup (2 sp.) ; Trochoderma 
Theel (1 sp.) ; Acanthotrochus Dan. and Cor. (1 sp.). 
The splitting up of the genus Synapta is mainly based on the pecu- 
liarities in the structure of the joint-end of the anchor-plates, but with 
these other peculiarities are associated. 
Synapta vivipara.§ — Dr. H. L. Clark has studied the development 
and structure of this species. The ova seem to pass into the body-cavity 
by a rupture of the peritoneal epithelium, while the spermatozoa pass 
outward through the genital duct. Spermatozoa may pass by way of the 
anus into the body-cavity, or perhaps through the water-pore and stone- 
canal. A complete blastula is formed in about four hours after fertilisa- 
tion. The first larval stage is elliptical, about a third of a millimetre 
in length, with the ventral ectoderm much thicker than the dorsal, with- 
out ciliated bands, calcareous particles, or nervous system, a mouth on 
* SB. Ges. Nat. Freunde Berlin, 1897, pp. 29-35 (10 figs ), 
f Journ. Linn. Soc. (Zool.), xxvi. (1898) pp. 456-64 (1 pi.), 
t Ofversigt K. Yet. Akad. Forhandl., lv. (1898) pp. 111-20 (8 figs.). 
§ Mem. Boston Soc. Nat. Hist., v. (1898) pp. 53-88 (5 pis.). 
