44 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
unpaired tentacle, in contact with the terminal plate ; water-tube opening 
by a single pore, and probably without any relation to a calcareous 
plate Five radial schizoccelic sinuses and perhaps an oral schizoccelic 
ring ; no masticating or lacunar apparatus. 
The axial enterocoel, which is rudimentary in Prosynapta, Proliolo- 
thuria and Procystus, would be well developed, and have in its interior 
a lymphatic gland. The gonads would take a radial form. 
It is suggested to give the name of Proaster to the common ancestor 
of Asteroidea and Ophiuroidea. The author imagines it to have had a 
pentagonal form of body, and to have been invested by calcareous 
plates ; at the apical pole a dorso-central, a ring of basals, and a ring of 
terminals ; between these two last would appear a new series, the radials. 
Digestive tube aproctous, and in the form of a globular sac ; nervous 
system superficial. Ambulacral apparatus identical with that of Echi- 
noids. The system of five radial schizoccelic sinuses, opening into an 
oral ring, would have communicated with the coelom on the one hand 
and the enterocoel on the other ; the latter would be well developed and 
inclose the ovoid gland which gives rise to the genital organs. The 
gonads radial. 
A steroidea. 
P roaster 
Ophiuroidea. 
Proechinus 
Echinoidea. 
Crinoidea. 
Procystus 
Blastoidea. 
\ 
Cystoidea. 
Proholothuria 
Holothurioidea. 
Prosynapta 
Synaptidfe. 
The author gives the accompanying table to illustrate his views, and 
urges as their recommendation that the ancestors follow one another 
perfectly and form an uninterrupted chain. 
Passing more to the details of the several groups, the author concludes 
his remarks by suggesting the following classification : — 
VI. Asteroidea. 
V. Ophiuroidea 
IV. Echinoidea .. 
III. Pelmatozoa .. 
II. Holothurioidea . . 
I. Synaptida. 
JOphiuraB. 
tEuryals. 
I I Palechinoidea. 
Gnathostomata <Kegulares. 
| Irregulares. 
Atelostomata. 
I Cystidea. 
Blastoidea. 
Crinoidea. 
fElasipoda fP^data f Aspidochirota. 
\Pneutnonophora < e \Dendrochirota. 
^Molpadidae. 
