ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
43 
which cause the destruction of the superjacent cuticula and thus expose 
the segments to the action of the intestinal juice. 
S. Incertee Sedis. 
Salinella.* — Prof. J. Frenzel has applied the name of Sallnella to 
the remarkable multicellular Infusorium-like animal of which he has 
already published a short description. f He points out the differences 
between Protozoa and Metazoa, and suggests that Salinella is a Mesozoon, 
or intermediate form between unicellular and multicellular animals. 
He regards it as a mid-gut animal, for its enteric epithelium is formed 
of typical mid-gut cells. He was able to observe the endogenous forma- 
tion of new cells in some of the larval cells, but was unable to carry his 
observations further. 
Echinodermata. 
Morphology of Echinodermata. j: — M. L. Cuenot, in his full paper, 
the abstract of which we have already noticed, § makes some suggestions 
as to the ancestry and classification of the Echinodermata. 
The common ancestor of the Synaptidfe would be Prosynapta (almost 
identical with the Pentactsea of Semon) ; it had a globular or elongated 
body with calcareous spicules ; a straight digestive tube with the blasto- 
pore or anus ; a superficial nervous system formed by five thickened 
ectodermal bands uniting in an oral ring, continuous with the endo- 
derrnic wall of the oesophagus ; an ambulacral apparatus formed by an 
oral ring and giving off five interradial tentacles and an aquiferous tube 
opening to the exterior by a single pore, with probably a Polian vesicle. 
It had five radial schizocoelic sinuses, but no lacunar apparatus. Gonads 
forming a group as in adult Synaptse. 
The common ancestor of the Holothurians (in his amended sense, 
that is, without the Synaptidse) would be Proholoihuria. It would have 
had a globular or elongated body with disconnected calcareous plates ; a 
straight or spiral digestive tube with the blastopore as anus. Nervous 
system as in Prosynapta. Ambulacral apparatus formed by an oral 
ring giving off five radial branches provided with ambulacral feet ; water 
tube as in Prosynapta ; the five radial ambulacral canals terminated by 
tentacles ranged in a circle around the blastopore. The rest as before. 
The common ancestor of the Pelmatozoa would be Procystus. It 
would have had a globular body but no stalk, the integument incrusted 
with calcareous plates (a dorso-central and several superposed rows 
arranged in alternate series, and in pentameral symmetry). The diges- 
tive tube would have had the form of a globular sac without an anal 
orifice ; the nervous system superficial ; ambulacral apparatus formed by 
an oral ring, giving off five radial branches with feet, a single water-tube. 
Five radial schizocoelic sinuses and gonads on the Holothurian type. 
The common ancestor of the Echinoids may be called Proechinus ; 
the globular body would have been entirely invested by calcareous plates, 
forming a definite series at the apical pole of a dorso-central, five inter- 
radial basal and five radial terminals. Digestive tube without an anus ; 
superficial nervous system ; the ambulacra would terminate by an 
* Biol. Centralbl., xi. (1891) pp. 577-81. f See this Journal, 1891, p. 602. 
X Archives de Biol., xi. (1891) pp. 313-680 (4 pis.). 
§ See this Journal, 1891, p. 746. 
