276 
surrounded by a jointed or notched ring is 
distinctly shown; in the specimen, I was un- 
able to make out these points satisfactorily; 
there seems little doubt about the terminal 
mouth, but the surrounding ring is ill-defined 
and I failed to see the joints. 
Dr. Walcott names and describes four 
genera, each with a single species, of what he 
believes to be holothurians. He apparently 
has not seen Giebel’s figures for he says (p. 
49) that his specimens record “for the first 
time, with the exception of some scattered 
calcareous spicules and plates, the presence of 
this class of organisms in any geological for- 
mation.” That he feels no serious doubts as 
to the fossils being holothurians is shown by 
the statement (p. 43) that they establish “the 
very ancient origin of the Class Holothurio- 
idea and the fact of its great differentiation in 
Middle Cambrian time,” and the assertion 
(p. 45) that “ The Holothuriide is represented 
by Laggania cambria and Lowisella peduncu- 
lata and the Synaptide by Mackenzia costalis. 
The Pelagothuride is indirectly represented 
by Eldonia ludwigi.” It is not clear what is 
meant by the Pelagothuriide being “ indi- 
rectly represented” by Hildonia since that 
genus is subsequently made the foundation of 
a new family, the Eldoniide, especially as Dr. 
Walcott later shows that his new genus has 
almost nothing in common with Pelagothuria. 
The material upon which Hldonia is based 
is abundant and much of it seems to be very 
well preserved, but of Laggania and Lowisella 
there are single specimens only, while of 
Mackenzia there are but two specimens and 
they differ from each other greatly. Of Lag- 
gania, Dr. Walcott says the mouth was “ ven- 
tral, near the anterior end and surrounded by 
a ring of plates.” “It is not practicable to 
make out the arrangement of the plate-like 
structure surrounding the mouth, as the cal- 
careous plates, if ever present, have disap- 
peared.” “Traces of tube-feet occur on the ven- 
tral surface” but “ the body of the animal is so 
completely flattened that the tube-feet are ob- 
secured.” I have sought in vain both in the 
figure and on the specimen for anything that 
could be called a tube-foot, without an exces- 
SCIENCE 
[N.S. Vou. XXXV. No. 894 
sive use of the imagination. Moreover the 
“ving of plates” surrounding the mouth does 
not remind one of the caleareous ring of a 
holothurian, but it does suggest to me the 
radiating folds surrounding the partially 
contracted oral disk of certain actinians and 
worms. Dr. Walcott calls attention to the 
surface markings of “indistinct concentric 
bands, each one of which is crossed by fine 
longitudinal lines.” This can be easily seen 
in the figure (at least in certain spots) with 
the aid of a lens. I do not recall any holo- 
thurian with such a surface, but it is sugges- 
tive of certain worms, and even some actin- 
ians have a somewhat similar exterior. On 
the whole it does not seem to me that Lag- 
gania can be positively assigned to any inver- 
tebrate phylum. I see nothing beyond the 
probable form of the body, and the terminal 
mouth, to suggest a holothurian, and these 
characters are equally suggestive of actinians. 
The specimen of Zouwisella seems to show 
more structure and Dr. Walcott says of it: 
With numerous tube-feet or podia in two longi- 
tudinal rows, and what may be papille on two 
peltate extensions at the posterior end... . The 
yentral sole is beautifully outlined by the marginal 
row of podia on each side. 
Examination of the specimen (or figure) 
shows of course what Dr. Walcott has called 
the “ventral sole” and “marginal rows of 
podia,” but neither is suggestive of any known 
holothurian excepting some of the bizarre 
Elasipod forms like Scotoplanes, to which Dr. 
Woleott refers. None of the podia are sufi- 
ciently defined to enable one to make out 
even the form, let alone the structure, 
whereas if they were really like those of 
Scotoplanes and other Elasipods, their rigid- 
ity would have caused them to be as well de- 
fined as any part of the body-outline. Dr. 
Waleott considers Lowisella a genus of the 
Holothuriide, but the size and arrangement 
of the supposed podia are entirely unlike any- 
thing known in that family. If Lowisella is 
a holothurian at all, its “ventral sole” and 
big podia (?) would suggest the Elasipods as 
its nearest allies, and the two extensions of 
the posterior end might be considered confirm- 
