ECHINODERMA, 5) 
frontal loop on to the dorsal surface, and also in the narrow oral field. But there are, 
nevertheless, irreconcilable differences between the two forms. The ciliated band of 
the Orotava larva in its lateral portions is produced into numerous secondary processes, 
so that the whole animal acquires the appearance of a Nudibranch molluse, whence 
the name A. nudibranchiata. Further, in this larva the post-oral processes are 
absent, but these are well marked (Plate I., fig. 1) in our larva, and though the 
primary processes are deeply marked there are no tag-like secondary processes such 
as exist in A. nudibranchiata. 
In spite of its considerable size (4 mm. long) our specimen is a young larva, 
for the ccelom is still in the form of a single unpaired vesicle (coe., fig. 1) com- 
municating with the exterior by a pore-canal. ; 
Reviewing all the evidence, we arrive at the conclusion that our larva is a 
new type of Auwricularia, to which the specific name “antarctica” may be given. 
It probably belongs to some large Holothurioid of the group Synaptidee. 
II. Post-LARVAL STAGES OF CUCUMARIA sp. 
The specimens composing this collection were mostly in a state of such intense 
contraction that their shape approximated to that of a sphere, but a few were 
considerably less contracted, and of these sections and whole mounts were made. 
In Pl. L., fig 3, one of the most successful of the whole mounts is shown. It will 
be seen that at the oral end of the body there is an atrium overarched by five valves, 
recalling the vestibule of a young Crinoid. In the intervals of the valves glimpses of 
the buccal tentacles can be seen. Of these there are ten, as we learn from transverse 
sections. The suckers of tube-feet can be seen to be developed along three radii. 
But the most striking feature in the preparation is the presence of numerous 
calcareous plates embedded in the skin, so numerous indeed as to constitute a veritable 
cuirass, especially over the dorsal surface; the plates do not touch edge to edge but overlap. 
Each oral valve is supported by a special plate. Between the rows of tube-feet there 
are also calcareous bodies to be found, but these are not fully formed plates. Through 
the semi-transparent tissues the outline of the alimentary canal can just be made out, 
and we can observe the thick cesophagus, the long stomach, and the shghtly bent 
intestine. 
Now the identification of these specimens as the young of some species of 
Cucumaria rests (i) on the number and shape of the buccal tentacles, (ii) on the nature 
of the calcareous plates embedded in the skin. 
With regard to the first point, Cucumaria is characterised by the possession of ten 
‘“‘dendrochirote” buccal tentacles, ie., tentacles which exhibit scattered lateral 
branches. Further, these tentacles are devoid of specially developed ampulle, but on 
the contrary the whole tentacle ring can be retracted as an introvert. With regard to the 
B 2 
