ANATOMY, HISTOLOGY, MORPHOLOGY, AND PHYLOGENY. Ech. 19 
nephridial or madreporic rather than genital. (3) Some general con- 
siderations (pp. 32-43). The author believes that the basal and radial 
plates, and possibly also the dorsocentral, constitute a fundamental part 
of the organization of every Echinoderm , except perhaps Holothurians , 
and that the apical aud oral systems of Echinoderms cannot be left out of 
consideration in any discussion respecting the phylogeny of the group. 
In a postscript (pp. 43-51) are discussed (1) the dorsocentral system ; 
(2) the water vascular system and its relations ; the view that the madre- 
poric system is a left nephridium has much to be said for it ; (3) the 
oscular orifice. 
Cu6not (1) discusses at considerable length the morphology and 
phylogeny of the different classes of Echinoderms. For list of species 
studied see pp. 314 & 315 ; for technique, pp. 316-318. Orientation 
(pp. 330-336) : the author considers the mouth or oral pole as the upper 
side, the aboral pole as the lower. The nomenclature of the radii proposed 
by Carpenter for Crinoids is adopted. Four planes of bilateral symmetry 
are recognized : (1) The Holothurian plaue, passing through the stone- 
canal and dorsal mesentery ; (2) the Echinid plane passing through the 
radius, B, interradius, D E ; (3) the plane of Lov6n, containing the anus 
in the Echinoids , in which it is eccentric, passing through the radius, D, 
interradius, A B ; (4) the Asteroid plane, passing through the radius, E, 
interradius, b e. Teguments (pp. 336-351). Muscular tissue (pp. 337- 
339). Connective tissue (pp. 340 & 341). Calcareous tissue (pp. 341-347). 
Body- wall (pp. 347-351) : In the young Amphiura squamata the ectoderm 
is distinct, but later becomes invaded by the mesoderm, so that it is 
impossible to distinguish between the two layers. Hence the ectoderm 
does not disappear as the result of friction, but becomes confounded 
with the mesoderm, and probably assists in the secretion of stereom. In 
Cucumaria the ectoderm cells are gathered into little separate masses 
imbedded in the connective tissue. Under each mass is a space filled by 
gelatinous ground substance, containing a large number of amibocytes; 
see pi. xxiv, fig. 4. Tegumentary appendages (351-369). Anchors of 
Synapta (pp. 352-354, pi. xxiv, fig. 6). Hooks of Ophiuroids (pp. 355 & 356), 
Radioles (pp. 356-365) : (1) defensive and ambulatory radioles in 
Echinoids, Crinoids (Arthroacantha), Ophiuroids , and Asteroids', (2) vibratile 
radioles in Asteroids and Glypeastroids. Pedicillariae (pp. 366-369). 
Cuvierian organs (pp. 369-374, pi. xxiv, fig. 19). Appendages of the 
body (pp. 383-386) : i.e., the stem of Crinoids and the “ aboral cone” of 
some Asteroids. Coelome (pp. 386-397). Synaptids and Holothurians 
(pp. 386 & 387). Crinoids (p. 388). Echinoids (pp. 388-391) : the small 
labial cavity of Spatangoids becomes greatly developed in Gnathostomes ? 
forming a closed peripharyngeal space containing the masticatory appa- 
ratus ; the external branchiae and organs of Stewart are diverticula of 
the peripharyngeal space, which perhaps represents the schizoccelic space 
under the nerve, and not a portion of the coelome. Ophiuroids (pp. 395 & 
396). Asteroids (p. 396). The perioesophageal spaces existing in Synaptids, 
Holothurians , Echinoids , and Ophiuroids, are probably not homologous 
