26 Eck, 
ECII1N0DERMATA. 
question is left undecided whether the supplementary costal is due to the 
reappearance by atavism of a fifth costal, or is the result of duplication 
of the fourth costal. 
de Loriol (3) describes some new facts about the stem and centro- 
dorsal of Thiolliericrinm ( v . T. insuetus , n. sp.), which are of importance 
if this genus be regarded as a link between Bourgueticrinidce and Ante • 
donidce. In Dolichocrinus, n. g., for Eugenicrinus aberrans, the author 
considers the indented base of the radial circlet as evidence that basals 
were present in the adult [though none have yet been found]. 
Ludwig (1) describes the anatomy of Ankyroderma musculus. Ten- 
tacles (p. 575), fifteen in number, each finger shaped with a minute lobe 
on each side near the end. The skin contains calcareous bodies (pp. 57G- 
579) of five kinds, figured on taf. xxix : fig. 1, figs. 2, 3, 4, & 5, fig. G, 
fig. 7, and fig. 8. In addition, the skin contains “ wine-red corpuscles ” 
(p. 580). These are not calcareous ; they are decolourized by acids, but 
not dissolved, unless the acid is very strong or acts for a long time, when 
they dissolve without giving off gas. The anal papillae (p. 582) are five 
in number, placed radially, and each consisting of an irregularly per- 
forated, elongated calcareous plate. Calcareous ring (p. 585), consisting 
of five radial pieces (taf. xxxix, fig. 10), and five interradial (fig. 1 1 , a & b). 
The peculiar distribution of the tentacles (p. 587, with diagram on p. 590) 
is connected with the symmetry of the lateral radial pieces, and the 
asymmetry of the median radial pieces of the calcareous ring. Sections 
through a radius of the body wall (p. 589) show the radial nerve, the 
pseudhaemal canal, and most internally the radial water-vessel, between 
which and the pseudhaemal canal are traces of a radial blood-vessel. The 
longitudinal muscles are paired in the trunk, but unpaired in the pos- 
terior tail-like region of the body, into which the radial water-vessels are 
continued. Each water-vessel gives off three tentacles. There are no 
retractor muscles. A single Polian vesicle is present. The stone-canal 
runs in the dorsal mesentery, and is attached to the skin. The sexes are 
separate, the genital caeca paired. Respiratory trees, alimentary canal, 
and blood-vessels (p. 591). 
The author proceeds to describe the position of Molpadiidce and the 
phylogeuy and classification of Holothurians in general. The Molpadiidce , 
in combining the absence of tube feet with the possession of respiratory 
trees, appear intermediate between Synaptidce , on the one hand, and the 
Aspido - and Dendrochirotce on the other; but in reality they are much 
more nearly related to the pedate Holothurians, and especially the Den- 
drochirotce, with which they agree closely in many points, as shown by a 
comparison of the organs of the Molpadiidce with those of other families 
(pp. 592-594). The Dendrochirotce, Molpadiidce, and Synaptidce are to be 
looked upon as arising from a common root, the Dendrochirotce repre- 
senting the main stem, which sent off early a branch, the Synaptidce, and 
later a second, the Molpadiidce. The Aspidochirotce are separated from all 
the other families by a number of points (p. 596), and represent a 
second main stem of the Holothurians, connected only at the root with 
